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| Publications of Paul A. Baker :chronological combined listing:
%% Papers Published
@article{fds186422,
Author = {Toney, J. and Y. Huang and S.C. Fritz and P.A. Baker and P. Nyren and E.
Grimm.},
Title = {Climatic and environmental controls on the occurrence and
distribution of long-chain alkenones in lakes of the
interior United States.},
Journal = {Geochimica Cosmochimica Acta},
Year = {2010},
url = {doi:10.1016/j.gca.2009.11.021},
Key = {fds186422}
}
@article{fds222725,
Author = {Jenkins, H.S. and Baker, P.A. and Negron-Juarez, R.I.},
Title = {Eventos extremos de seca na Amazonia revelados pelos
registros de aneis de arvores},
Pages = {29-46},
Booktitle = {Secas na Amazonia},
Year = {2013},
Key = {fds222725}
}
@article{fds215099,
Author = {Jenkins, HS and Baker PA and Negrón-Juárez
RI},
Title = {Extreme drought events revealed in Amazon tree ring
records},
Booktitle = {Amazonian Droughts: A Review},
Year = {2012},
Key = {fds215099}
}
@article{fds215101,
Author = {Clark, P.U. and Shakun, J.D. and Baker, P.A. and et
al.},
Title = {Global climate evolution during the last
deglaciation},
Journal = {PNAS},
Year = {2012},
Key = {fds215101}
}
@article{fds186423,
Author = {Fritz, S.C. and Baker, P.A. and Ekdahl, E. and Seltzer, G.O. and Stevens, L.R},
Title = {Millennial-scale climate variability during the last glacial
period in the tropical Andes},
Journal = {Quaternary Science Reviews},
Year = {2010},
Key = {fds186423}
}
%% Papers Accepted
@article{fds278649,
Author = {Elderfield, H and Gieskes, JM and Baker, PA and Oldfield, RK and Hawkesworth, CJ and Miller, R},
Title = {87Sr 86Sr and 18O
16O ratios, interstitial water chemistry and
diagenesis in deep-sea carbonate sediments of the Ontong
Java Plateau},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {46},
Number = {11},
Pages = {2259-2268},
Publisher = {Elsevier BV},
Year = {1982},
ISSN = {0016-7037},
url = {http://dx.doi.org/10.1016/0016-7037(82)90199-5},
Abstract = {Interstitial waters and sediments from DSDP sites 288 and
289 contain information on the chemistry and diagenesis of
carbonate in deep-sea sediments and on the role of volcanic
matter alteration processes. Sr Ca ratios are species
dependent in unaltered foraminifera from site 289 and atom
ratios (1.2-1.6 × 10-3) exceed those predicted by
distribution coefficent data (~0.4 × 10-3). During
diagenesis Sr Ca ratios of carbonates decrease and reach the
theoretical distribution at a depth which is identical to
the depth of Sr isotopic equilibration, where 87Sr 86Sr
ratios of interstitial waters and carbonates converge. Mg Ca
ratios in the carbonates do not increase with depth as found
in some other DSDP sites, possibly because of diagenetic
re-equilibration with interstitial waters showing decreasing
Mg2+/Ca2+ ratios with depth due to Ca input and Mg removal
by alteration of volcanic matter. Interstitial 18O 16O
ratios increase with depth at site 289 to δ18O = 0.67%.
(SMOW), reflecting carbonate recrystallization at elevated
temperatures ( $ ̌= 20°C), the first recorded evidence of
this effect in interstitial waters. Interstitial Sr2+
concentrations reach high levels, up to 1 mM, chiefly
because of carbonate recrystallization. However, 87Sr 86Sr
ratios decrease from 0.7092 to less than 0.7078, lower than
for contemporaneous sea water, showing that there is a
volcanic input of strontium at depth. This volcanic
component is recorded in the Sr isotopic composition of
recrystallized calcites. Isotopic compositions of the
unrecrystallized calcites suggests that the rate of increase
of the 87Sr 86Sr ratio of sea water with time has been
faster since 3 my ago than in the preceding 13 my. ©
1982.},
Doi = {10.1016/0016-7037(82)90199-5},
Key = {fds278649}
}
@article{fds278712,
Author = {Hanselman, JA and Bush, MB and Gosling, WD and Collins, A and Knox, C and Baker, PA and Fritz, SC},
Title = {A 370,000-year record of vegetation and fire history around
Lake Titicaca (Bolivia/Peru)},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {305},
Number = {1-4},
Pages = {201-214},
Publisher = {Elsevier BV},
Year = {2011},
Month = {May},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/j.palaeo.2011.03.002},
Abstract = {Fossil pollen and charcoal analyses of sediments from Lake
Titicaca, Peru/Bolivia, provide a record of palaeoclimatic
variation spanning four full glacial cycles. Pollen, aquatic
microfossils, and charcoal, as well as previously published
data including diatom assemblages, carbonate content, and
stable carbon isotopic ratios of organic carbon, indicate
that interglacials were warm and dry whereas the peaks of
glacials were cold and wet. Each of the interglacials
documented in the record are somewhat different, with those
of MIS 5e and MIS 9 inducing lower lake levels and a drier
vegetation signature than those of MIS 7 and 1. The presence
of charcoal particles in sediments deposited during previous
interglacials provides evidence of the long-term role of
fire in shaping Andean ecosystems. © 2011 Elsevier
B.V.},
Doi = {10.1016/j.palaeo.2011.03.002},
Key = {fds278712}
}
@article{fds278633,
Author = {Fornace, KL and Hughen, KA and Shanahan, TM and Fritz, SC and Baker, PA and Sylva, SP},
Title = {A 60,000-year record of hydrologic variability in the
Central Andes from the hydrogen isotopic composition of leaf
waxes in Lake Titicaca sediments},
Journal = {Earth and Planetary Science Letters},
Volume = {408},
Pages = {263-271},
Publisher = {Elsevier BV},
Year = {2014},
Month = {December},
ISSN = {0012-821X},
url = {http://dx.doi.org/10.1016/j.epsl.2014.10.024},
Abstract = {A record of the hydrogen isotopic composition of terrestrial
leaf waxes (δDwax) in sediment cores from Lake Titicaca
provides new insight into the precipitation history of the
Central Andes and controls of South American Summer Monsoon
(SASM) variability since the last glacial period. Comparison
of the δDwax record with a 19-kyr δD record from the
nearby Illimani ice core supports the interpretation that
precipitation δD is the primary control on δDwax with a
lesser but significant role for local evapotranspiration and
other secondary influences on δDwax. The Titicaca δDwax
record confirms overall wetter conditions in the Central
Andes during the last glacial period relative to a drier
Holocene. During the last deglaciation, abrupt δDwax shifts
correspond to millennial-scale events observed in the
high-latitude North Atlantic, with dry conditions
corresponding to the Bølling-Allerød and early Holocene
periods and wetter conditions during late glacial and
Younger Dryas intervals. We observe a trend of increasing
monsoonal precipitation from the early to the late Holocene,
consistent with summer insolation forcing of the SASM, but
similar hydrologic variability on precessional timescales is
not apparent during the last glacial period. Overall, this
study demonstrates the relative importance of high-latitude
versus tropical forcing as a dominant control on glacial
SASM precipitation variability.},
Doi = {10.1016/j.epsl.2014.10.024},
Key = {fds278633}
}
@article{fds278654,
Author = {Burns, SJ and Baker, PA},
Title = {A geochemical study of dolomite in the Monterey Formation,
California.},
Journal = {Journal of Sedimentary Petrology},
Volume = {57},
Number = {1},
Pages = {128-139},
Publisher = {Society for Sedimentary Geology},
Year = {1987},
Month = {January},
ISSN = {0022-4472},
url = {http://dx.doi.org/10.1306/212F8AC6-2B24-11D7-8648000102C1865D},
Abstract = {Monterey sections with dolomites with low trace-element
contents contain higher percentages of dolomite and have
lower sedimentation rates and lower detrital mineral
contents than sections with dolomites with high
trace-element contents. Differences in iron and manganese
contents of dolomites from different sections are probably
attributable to variation in the amount of readily available
iron and possible manganese oxide coatings on detrital
minerals. Whether a dolomite forms in or below the zone of
organic-matter oxidation by microbial sulfate reduction also
may affect the availability of iron and manganese. In the
zone of sulfate reduction, reduced iron, and possibly
manganese, may be precipitated as sulfide minerals rather
than be incorporated into dolomite. -from
Authors},
Doi = {10.1306/212F8AC6-2B24-11D7-8648000102C1865D},
Key = {fds278654}
}
@article{fds278696,
Author = {Tapia, PM and Fritz, SC and Baker, PA and Seltzer, GO and Dunbar,
RB},
Title = {A late quaternary diatom record of tropical climatic history
from Lake Titicaca (Peru and Bolivia)},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {194},
Number = {1-3},
Pages = {139-164},
Publisher = {Elsevier BV},
Year = {2003},
Month = {May},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/S0031-0182(03)00275-X},
Abstract = {A composite high-resolution diatom stratigraphy from three
piston cores and one box-core in the deep sub-basin of Lake
Titicaca reveals large moisture variations during the past
30 kyr in the Altiplano region. Diatom sequences indicate
orbital and millennial-scale variability in water level and
salinity. The pelagic freshwater diatom species Cyclotella
andina and Cyclotella stelligera dominate Glacial-age
sediments, suggesting that the lake was above its present
outlet, Generally, wet conditions continued until 11 000 cal
yr BP, as indicated by high percentages of freshwater
planktonic diatoms. Large pulses of benthic diatom species
between about 11 000 and 10 000 cal yr BP suggest brief
intervals of large-amplitude declines in lake level. During
the early Holocene (10 000-8500 cal yr BP), a freshwater
diatom assemblage suggests overflowing conditions. Pelagic
freshwater diatoms are replaced ca, 8500 cal yr BP by the
salinity-indifferent species Cyclotella meneghiniana and by
benthic taxa, indicating the beginning of lake regression.
During the mid-Holocene (6000-3500 cal yr BP), the abundance
of the saline taxon Chaetoceros muelleri, coupled with high
abundances of epiphytic and epipelic diatoms, indicates
maximum salinity and lowest lake levels in the entire 30 000
year record. Lake transgression began ca. 4000 cal yr BP,
and the lake achieved modern levels by about 1500 cal yr BP.
These water-level changes imply changes in effective
moisture, most likely resulting from large precipitation
changes. Precipitation was high throughout the Last Glacial
Maximum (21 000-18 000 cal yr BP), likely due to an enhanced
South American Summer Monsoon during peak summer insolation
in the Southern Hemisphere. In contrast, the mid-Holocene
transition was dryer than today in association with an
austral summer insolation minimum and the subsequent
weakening of the summer monsoon. © 2003 Elsevier Science
B.V. All rights reserved.},
Doi = {10.1016/S0031-0182(03)00275-X},
Key = {fds278696}
}
@article{fds278683,
Author = {Cross, SL and Baker, PA and Seltzer, GO and Fritz, SC and Dunbar,
RB},
Title = {A new estimate of the Holocene lowstand level of Lake
Titicaca, central Andes, and implications for tropical
palaeohydrology},
Journal = {The Holocene},
Volume = {10},
Number = {1},
Pages = {21-32},
Publisher = {SAGE Publications},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1191/095968300671452546},
Abstract = {New evidence from piston cores and high-resolution seismic
reflection data shows that water levels in Lake Titicaca
were as much as 100 m below the present level during the
early to mid-Holocene (between >6 and 3.8 14C kyr BP).
Climatological and modelling studies indicate that Lake
Titicaca rainfall depends on convective activity in upwind
Amazonia; the lake-level data therefore suggest a drier
Amazon Basin during this time. This view is bolstered by an
excellent match between the Titicaca lake-level curve and
decreased methane concentrations in Greenland ice,
previously ascribed to drying of low-latitude wetlands
(Blunier et al., 1995). The postglacial history of Lake
Titicaca fits a global pattern of lake-level change in the
tropics, characterized by opposite phasing between the
Southern and Northern Hemispheres. This pattern is most
likely the result of orbital controls over the intensity of
summer insolation.},
Doi = {10.1191/095968300671452546},
Key = {fds278683}
}
@article{fds278669,
Author = {Baker, PA and Cross, SL},
Title = {A note on the carbon, sulfur, and nitrogen contents of
hydrothermally altered sediments, Middle Valley, Juan de
Fuca Ridge},
Journal = {Proc., Scientific Results, Odp Leg 139, Middle Valley, Juan
De Fuca Ridge},
Pages = {307-312},
Year = {1994},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.139.214.1994},
Abstract = {Inorganic carbon varies inversely with organic carbon
throughout much of the sediment column. This results from
the precipitation of diagenetic carbonate cements that
contain carbon partly derived from an organic carbon source.
This organic carbon may be of remote or in-situ derivation.
Most importantly, sulfur content and sulfur isotopic,
compositions of sulfides increase with increasing burial
depth. -from Authors},
Doi = {10.2973/odp.proc.sr.139.214.1994},
Key = {fds278669}
}
@article{fds278697,
Author = {Paduano, GM and Bush, MB and Baker, PA and Fritz, SC and Seltzer,
GO},
Title = {A vegetation and fire history of Lake Titicaca since the
last glacial maximum},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {194},
Number = {1-3},
Pages = {259-279},
Publisher = {Elsevier BV},
Year = {2003},
Month = {May},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/S0031-0182(03)00281-5},
Abstract = {Fine-resolution fossil pollen and charcoal analyses
reconstruct a vegetation and fire history in the area
surrounding Lake Titicaca (3810 m, Peru/Bolivia) since ca,
27 500 cal yr BP (hereafter BP). Time control was based on
26 accelerator mass spectrometer (AMS) radiocarbon dates.
Seventeen AMS dates and 155 pollen and charcoal samples
between ca. 17 500 BP and ca. 3100 BP allow a
centennial-scale reconstruction of deglacial and early- to
mid-Holocene events. Local and regional fire signals were
based on the separation of two charcoal size fractions, ≥
180 μm and 179-65 μm. Charcoal abundance correlated
closely with the proportion of woody taxa present in the
pollen spectra. Little or no pollen was detected in the
sedimentary record prior to ca. 21 000 BP. Very cold
climatic conditions prevailed, with temperatures suggested
to be at least 5-8°C cooler than present. Increases in
pollen concentration suggest initial warming at ca. 21 000
BP with a more significant transition toward deglaciation
ca. 17 700 BP. Between 17 700 BP and 13 700 BP, puna brava
is progressively replaced by puna and sub-puna elements. The
most significant changes between the Pleistocene and the
Holocene floras were largely complete by 13 700 BP,
providing an effective onset of near-modern conditions
markedly earlier than in other Andean records. Fire first
occurs in the catchment at ca. 17 700 BP and becomes
progressively more important as fuel loads increase. No
evidence is found of a rapid cooling and warming coincident
with the Younger Dryas chron. A dry event between ca. 9000
BP and 3100 BP, with a peak between 6000 and 4000 BP, is
inferred from changes in the composition of aquatics, and
the marsh community as pollen of Cyperaceae is replaced by
Poaceae, Apiaceae, Plantago and the shrub Polylepis. Human
disturbance of the landscape is evident in the pollen
spectra after ca. 3100 BP with the appearance of weed
species. © 2003 Elsevier Science B.V. All rights
reserved.},
Doi = {10.1016/S0031-0182(03)00281-5},
Key = {fds278697}
}
@article{fds336123,
Author = {Weide, DM and Fritz, SC and Hastorf, CA and Bruno, MC and Baker, PA and Guedron, S and Salenbien, W},
Title = {A ∼6000 yr diatom record of mid- to late Holocene
fluctuations in the level of Lago Wiñaymarca, Lake Titicaca
(Peru/Bolivia)},
Journal = {Quaternary Research},
Volume = {88},
Number = {2},
Pages = {179-192},
Publisher = {Cambridge University Press (CUP)},
Year = {2017},
Month = {September},
url = {http://dx.doi.org/10.1017/qua.2017.49},
Abstract = {A multidecadal-scale lake-level reconstruction for Lago
Wiñaymarca, the southern basin of Lake Titicaca, has been
generated from diatom species abundance data. These data
suggest that ~6500 cal yr BP Lago Wiñaymarca was dry, as
indicated by a sediment unconformity. At ~4400 cal yr BP,
the basin began to fill, as indicated by the dominance of
shallow epiphytic species. It remained somewhat saline with
extensive wetlands and abundant aquatic plants until ~3800
cal yr BP, when epiphytic species were replaced by planktic
saline-indifferent species, suggesting a saline shallow
lake. Wiñaymarca remained a relatively shallow lake that
fluctuated on a multidecadal scale until ~1250 cal yr BP,
when freshwater planktic species increased, suggesting a
rise in lake level with a concomitant decrease in salinity.
The lake became gradually fresher, dominated by deep,
freshwater species from ~850 cal yr BP. By ~80 cal yr BP,
saline-tolerant species were rare, and the lake was
dominated by freshwater planktic diatoms, resembling the
fresh and deep lake of today. These results reveal a more
dynamic and chronologically specific record of lake-level
fluctuations and associated ecological conditions that
provide important new data for paleoclimatologists and
archaeologists, to better understand human-environmental
dynamics during the mid- to late Holocene.},
Doi = {10.1017/qua.2017.49},
Key = {fds336123}
}
@article{fds278694,
Author = {Grove, MJ and Baker, PA and Cross, SL and Rigsby, CA and Seltzer,
GO},
Title = {Application of strontium isotopes to understanding the
hydrology and paleohydrology of the Altiplano,
Bolivia-Peru},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {194},
Number = {1-3},
Pages = {281-297},
Publisher = {Elsevier BV},
Year = {2003},
Month = {May},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/S0031-0182(03)00282-7},
Abstract = {Strontium concentrations and strontium isotopic ratios were
measured in natural waters and carbonate sediments from
throughout the Bolivian and Peruvian Altiplano in order to
improve hydrologic and paleohydrologic mass balances with
the ultimate goal of better understanding the paleoclimatic
history of the central Andes. Rivers flowing into Lake
Titicaca have a wide range of strontium isotopic ratios that
exhibit spatial patterns consistent with the lithologies of
the different drainage basins. Because of the limited
exchange of water between the two main sub-basins of Lake
Titicaca, Lago Grande and Lago Huiñaimarca, and between the
sub-basins of Lago Huiñaimarca, there are significant
differences in strontium isotopic ratios between the
sub-basins. Calculated elemental balances of strontium in
Lake Titicaca are in reasonable agreement with previously
published budgets of water and major elements. However, the
strontium isotopic budget indicates that the lake is not in
isotopic steady state. This also implies that the
major-element budgets are unlikely to be in steady state.
Lake Titicaca had a higher-than-modern strontium isotopic
ratio during the early and middle Holocene. Elevated values
persisted in Lago Grande until at least 2000 cal yr BP,
consistent with other evidence that modern hydrologic
conditions (namely overflow) were not established until that
time. An isotopic budget calculated for late-Pleistocene
paleolake Tauca in the central Altiplano suggests that
between 70% and 83% of its riverine inputs were derived from
Lake Titicaca overflow. This calculated flow represents
about a 30-fold increase over the average discharge of the
modern Río Desaguadero at Desaguadero or a seven-fold
increase over its average discharge into Lago Poopó. The
strontium isotopic budget (if complete) precludes the
possibility that decreased evaporation alone could have
accounted for the existence of paleolake Tauca. © 2003
Elsevier Science B.V. All rights reserved.},
Doi = {10.1016/S0031-0182(03)00282-7},
Key = {fds278694}
}
@article{fds328727,
Author = {Boardman, MR and Neumann, AC and Baker, PA and Dulin, LA and Kenter, RJ and Hunter, GE and Kiefer, KB},
Title = {Banktop responses to Quaternary fluctuations in sea level
recorded in periplatform sediments},
Journal = {Geology},
Volume = {14},
Number = {1},
Pages = {28-28},
Publisher = {Geological Society of America},
Year = {1986},
url = {http://dx.doi.org/10.1130/0091-7613(1986)14<28:brtqfi>2.0.co;2},
Doi = {10.1130/0091-7613(1986)14<28:brtqfi>2.0.co;2},
Key = {fds328727}
}
@article{fds357962,
Author = {Ferreira, F and Silva, CG and Oliveira, AS and Chiessi, CM and Kern, AK and Baker, PA and Dwyer, G and Rigsby, CA and Huang, E and Tian,
J},
Title = {Biochronostratigraphy of the western equatorial Atlantic for
the last 1.93 Ma},
Journal = {Quaternary International},
Volume = {598},
Pages = {24-37},
Year = {2021},
Month = {October},
url = {http://dx.doi.org/10.1016/j.quaint.2021.04.042},
Abstract = {Planktonic foraminifera are an important
biochronostratigraphic tool and one of the main proxies used
in paleoceanographic studies. Here we present the
integration of quantitative analyses of planktonic
foraminifera biostratigraphy, planktonic and benthic
foraminifera oxygen isotopic data, and planktonic
foraminifera radiocarbon ages in a biochronostratigraphic
framework for the last 1.93 Ma of the western equatorial
Atlantic. The ages of the biostratigraphic events derived
from our records are consistent with previous works except
for the highest occurrences of Globigerinoidesella fistulosa
(~1.82 Ma; MIS 66), Globigerinoides obliquus (~1.48 Ma; MIS
49), Globorotalia tosaensis (~1.05 Ma; MIS 31), and G. viola
(~0.34 Ma; MIS 10). The largest difference in age (~1.13 Ma)
was found for the highest occurrence of G. viola. In
addition, we describe for the first time in the equatorial
and western South Atlantic the oldest Pleistocene
Globorotalia menardii disappearance (D) and reappearance (R)
events D5 (~1.79 Ma; MIS 64), R5 (~1.68 Ma; MIS 60), D4
(~1.05 Ma; MIS 30) and R4 (~0.96 Ma; MIS 26). Our records
present a consistent difference in the ages of G. menardii D
and R events compared to the North and South Atlantic. While
the onset of D events occurs initially at high latitudes and
later in the equatorial region, the timing of R events
exhibit the opposite trend. The oscillations in abundance of
the complexes Pulleniatina and Globorotalia crassaformis
together with the species Globorotalia truncatulinoides and
Globoconella inflata allowed the subdivision of the last
1.93 Ma into 20 subzones, substantially improving the
biochronostratigraphic resolution for the western equatorial
Atlantic.},
Doi = {10.1016/j.quaint.2021.04.042},
Key = {fds357962}
}
@article{fds278725,
Author = {Williams, HL and Baker, PA},
Title = {Carbon cap and trade: How Wall Street will game the regs and
trash the planet},
Journal = {Counterpunch (Online)},
Year = {2009},
Key = {fds278725}
}
@article{fds278716,
Author = {Fritz, SC and Björck, S and Rigsby, CA and Baker, PA and Calder-Church,
A and Conley, DJ},
Title = {Caribbean hydrological variability during the Holocene as
reconstructed from crater lakes on the island of
Grenada},
Journal = {Journal of Quaternary Science},
Volume = {26},
Number = {8},
Pages = {829-838},
Publisher = {WILEY},
Year = {2011},
Month = {November},
ISSN = {0267-8179},
url = {http://dx.doi.org/10.1002/jqs.1512},
Abstract = {Contemporary precipitation patterns in the Caribbean region
are spatially variable, and the small number of Holocene
paleoclimatic records may not adequately capture patterns of
variation in the past. The hydrological history of Grenada
was inferred from paleolimnological analyses of sediment
cores from two crater lakes on the island. The basins were
formed by volcanic activity some time during the Last
Termination, but were dry between ca 13000 and ca 7200cal a
BP. After filling, the lakes were initially very shallow,
and sedimentation was interrupted by a hiatus ca
6300-5500cal a BP, followed by deposition of a thick tephra
in both sites. After 5500cal a BP, lake level shows
considerable multi-centennial variability, superimposed upon
a long-term trend of generally higher lake level after
3200cal a BP. The pattern of lake-level variation in Grenada
shows some similarity with other Caribbean paleoclimatic
records in terms of the timing of transitions, but differs
from several classic studies in the sign of inferred
precipitation change. The differences among records may
reflect spatially variable precipitation patterns in the
past in response to the position of the Intertropical
Convergence Zone and to sea surface temperature influences
on the trade winds and Caribbean low-level jet. © 2011 John
Wiley & Sons, Ltd.},
Doi = {10.1002/jqs.1512},
Key = {fds278716}
}
@article{fds278665,
Author = {Dunbar, RB and Marty, RC and Baker, PA},
Title = {Cenozoic marine sedimentation in the Sechura and Pisco
basins, Peru},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {77},
Number = {3-4},
Pages = {235-261},
Publisher = {Elsevier BV},
Year = {1990},
Month = {January},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/0031-0182(90)90179-B},
Abstract = {The central and northern Peruvian margin consists of a
series of 8 paired forearc basins which may be separated
into an inner set of shelf basins and a seaward set of slope
basins. We have examined the Cenozoic stratigraphy of the
onshore portions of the Sechura Basin (5-7°S) and Pisco
Basin (13-16°S), two shelf basins which have accumulated
marine sediment discontinuously since the mid to late
Eocene. Cenozoic sediments in the Pisco Basin were deposited
during at least three major transgressive cycles. Each
sequence is preserved as a similar vertical progression of
facies including coarse nearshore bioclastic conglomerates
and sandstones grading upwards into sandy siltstones and
mudstones, and capped by biogenic deposits including
diatomites, diatomaceous mudstones, dolomitic horizons, and
phosphate deposits. Stratigraphic nomenclature for the Pisco
Basin has recently evolved; a stratigraphy presented here
includes the Eocene Caballas Fm., upper Eocene Los Choros
fm., upper Eocene to lowermost Oligocene Yumaque fm.,
uppermost Oligocene to middle Miocene Chilcatay fm., and
upper Miocene to Pliocene Pisco Fm. Major hiatuses in the
Pisco Basin span the Late Cretaceous to middle Eocene, early
to late Oligocene, middle Miocene, and late
Pliocene/Pleistocene to Recent. Cenozoic sediments of the
Sechura Basin were deposited within at least 4 major
transgressive cycles with hiatuses during the Paleocene to
middle Eocene, Oligocene, early to middle Miocene, and late
Miocene. Based on recent biostratigraphic studies, sediments
enriched in biogenic components accumulated between about
40-36 Ma, 24-16 Ma, and 11-3 Ma in the Pisco Basin and
between 40-37 Ma and 8.5-4.5 Ma in the Sechura Basin. In
both basins, the most diatomaceous sediments are restricted
to the Late Eocene and Late Miocene through Pliocene. The
temporal distribution of biogenic sediments suggests that
high productivity conditions linked to coastal upwelling
have occurred episodically since at least the Late Eocene.
The occurrence of diatomites and phosphorites is diachronous
between the Pisco and Sechura Basins and between the
Peruvian forearc and other circum-Pacific Monterey Formation
analogs, a reflection of the strong influence of local
tectonism on sedimentation patterns. The volume of Neogene
sediments along the Peruvian forearc is nearly twice that of
the Monterey Fm.; despite basin-to-basin facies
diachroneity, these deposits very likely contributed to
fluctuations of the late Miocene carbon/CO2 system by acting
as large carbon sinks. © 1990.},
Doi = {10.1016/0031-0182(90)90179-B},
Key = {fds278665}
}
@article{fds322136,
Author = {Dwyer, GS and Cronin, TM and Baker, PA and Rodriguez-Lazaro,
J},
Title = {Changes in North Atlantic deep-sea temperature during
climatic fluctuations of the last 25,000 years based on
ostracode Mg/Ca ratios},
Journal = {Geochemistry, Geophysics, Geosystems},
Volume = {1},
Number = {12},
Pages = {n/a-n/a},
Publisher = {American Geophysical Union (AGU)},
Year = {2000},
Month = {December},
url = {http://dx.doi.org/10.1029/2000GC000046},
Abstract = {We reconstructed three time series of last
glacial-to-present deep-sea temperature from deep and
intermediate water sediment cores from the western North
Atlantic using Mg/Ca ratios of benthic ostracode shells.
Although the Mg/Ca data show considerable variability
("scatter") that is common to single-shell chemical
analyses, comparisons between cores, between core top shells
and modern bottom water temperatures (BWT), and comparison
to other paleo-BWT proxies, among other factors, suggest
that multiple-shell average Mg/Ca ratios provide reliable
estimates of BWT history at these sites. The BWT records
show not only glacial-to-interglacial variations but also
indicate BWT changes during the deglacial and within the
Holocene interglacial stage. At the deeper sites (4500- and
3400-m water depth), BWT decreased during the last glacial
maximum (LGM), the late Holocene, and possibly during the
Younger Dryas. Maximum deep-sea warming occurred during the
latest deglacial and early Holocene, when BWT exceeded
modern values by as much as 2.5°C. This warming was
apparently most intense around 3000 m, the depth of the
modern-day core of North Atlantic deep water (NADW). The BWT
variations at the deeper water sites are consistent with
changes in thermohaline circulation: warmer BWT signifies
enhanced NADW influence relative to Antarctic bottom water
(AABW). Thus maximum NADW production and associated heat
flux likely occurred during the early Holocene and decreased
abruptly around 6500 years B.P., a finding that is largely
consistent with paleonutrient studies in the deep North
Atlantic. BWT changes in intermediate waters (1000-m water
depth) of the subtropical gyre roughly parallel the deep BWT
variations including dramatic mid-Holocene cooling of around
4°C. Joint consideration of the Mg/Ca-based BWT estimates
and benthic oxygen isotopes suggests that the cooling was
accompanied by a decrease in salinity at this site.
Subsequently, intermediate waters warmed to modern values
that match those of the early Holocene maximum of ∼7°C.
Intermediate water BWT changes must also be driven by
changes in ocean circulation. These results thus provide
independent evidence that supports the hypothesis that
deep-ocean circulation is closely linked to climate change
over a range of timescales regardless of the mean climate
state. More generally, the results further demonstrate the
potential of benthic Mg/Ca ratios as a tool for
reconstructing past ocean and climate conditions.},
Doi = {10.1029/2000GC000046},
Key = {fds322136}
}
@article{fds278634,
Author = {Obrochta, SP and Crowley, TJ and Channell, JET and Hodell, DA and Baker,
PA and Seki, A and Yokoyama, Y},
Title = {Climate variability and ice-sheet dynamics during the last
three glaciations},
Journal = {Earth and Planetary Science Letters},
Volume = {406},
Pages = {198-212},
Publisher = {Elsevier BV},
Year = {2014},
Month = {November},
ISSN = {0012-821X},
url = {http://dx.doi.org/10.1016/j.epsl.2014.09.004},
Abstract = {A composite North Atlantic record from DSDP Site 609 and
IODP Site U1308 spans the past 300,000 years and shows that
variability within the penultimate glaciation differed
substantially from that of the surrounding two glaciations.
Hematite-stained grains exhibit similar repetitive down-core
variations within the Marine Isotope Stage (MIS) 8 and 4-2
intervals, but little cyclic variability within the MIS 6
section. There is also no petrologic evidence, in terms of
detrital carbonate-rich (Heinrich) layers, for surging of
the Laurentide Ice Sheet through the Hudson Strait during
MIS 6. Rather, very high background concentration of
iceberg-rafted debris (IRD) indicates near continuous
glacial meltwater input that likely increased thermohaline
disruption sensitivity to relatively weak forcing events,
such as expanded sea ice over deepwater formation sites.
Altered (sub)tropical precipitation patterns and Antarctic
warming during high orbital precession and low 65°N summer
insolation appear related to high abundance of Icelandic
glass shards and southward sea ice expansion. Differing
European and North American ice sheet configurations,
perhaps aided by larger variations in eccentricity leading
to cooler summers, may have contributed to the relative
stability of the Laurentide Ice Sheet in the Hudson Strait
region during MIS 6.},
Doi = {10.1016/j.epsl.2014.09.004},
Key = {fds278634}
}
@article{fds278717,
Author = {Ballantyne, AP and Baker, PA and Fritz, SC and Poulter,
B},
Title = {Climate-mediated nitrogen and carbon dynamics in a tropical
watershed},
Journal = {Journal of Geophysical Research},
Volume = {116},
Number = {G2},
Publisher = {American Geophysical Union (AGU)},
Year = {2011},
Month = {May},
ISSN = {0148-0227},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000290933300001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Doi = {10.1029/2010jg001496},
Key = {fds278717}
}
@article{fds278724,
Author = {Toney, JL and Huang, Y and Fritz, SC and Baker, PA and Grimm, E and Nyren,
P},
Title = {Climatic and environmental controls on the occurrence and
distributions of long chain alkenones in lakes of the
interior United States},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {74},
Number = {5},
Pages = {1563-1578},
Publisher = {Elsevier BV},
Year = {2010},
Month = {March},
ISSN = {0016-7037},
url = {http://dx.doi.org/10.1016/j.gca.2009.11.021},
Abstract = {Long chain alkenones (LCA) are temperature-sensitive lipids
with great potential for quantitative reconstruction of past
continental climate. We conducted the first survey for
alkenone biomarkers from 55 different lakes in the Northern
Great Plains and Nebraska Sand Hills of the United States.
Among those surveyed, we found 13 lakes that contain LCAs in
the surface sediments. The highest concentrations of
alkenones in sediments are found in cold (mean annual air
temperature ∼11 °C versus 17 °C in our warmest sites),
brackish to mesosaline (salinity = 8.5-9.7 g/L), and
alkaline (pH = 8.4-9.0) lakes with high concentrations of
sodium and sulfate. The dynamics of stratification and
nutrient availability also appear to play a role in LCA
abundance, as early spring mixing promotes a bloom of
alkenone-producing haptophytes. Four of the
alkenone-containing sites contain the C37:4 alkenone;
however, we discovered an unprecedented lacustrine alkenone
distribution in a cluster of lakes, with a total absence of
C37:4 alkenone. We attribute this unusual composition to a
different haptophyte species and show that the
sulfate:carbonate ratio may control the occurrence of these
two distinct populations. We created a new in-situ
temperature calibration for lacustrine sites that contain
C37:4 using a water-column calibration from Lake George, ND
and show that U37K is linearly correlated to lake water
temperature (R2 = 0.74), but U37K′ is not. A number of
lakes contain an unidentified compound series that elutes
close to the LCAs, highlighting the importance of routine
GC-MS examination prior to using lacustrine LCAs for
paleotemperature reconstructions. © 2009 Elsevier Ltd. All
rights reserved.},
Doi = {10.1016/j.gca.2009.11.021},
Key = {fds278724}
}
@article{fds362121,
Author = {Jiskra, M and Guédron, S and Tolu, J and Fritz, SC and Baker, PA and Sonke, JE},
Title = {Climatic Controls on a Holocene Mercury Stable Isotope
Sediment Record of Lake Titicaca},
Journal = {Acs Earth and Space Chemistry},
Volume = {6},
Number = {2},
Pages = {346-357},
Year = {2022},
Month = {February},
url = {http://dx.doi.org/10.1021/acsearthspacechem.1c00304},
Abstract = {Mercury (Hg) records in sediment archives inform past
patterns of Hg deposition and the anthropogenic contribution
to global Hg cycling. Natural climate variations complicate
the interpretation of past Hg accumulation rates (HgARs),
warranting additional research. Here, we investigated Hg
stable isotopes in a ca. 8k year-long sediment core of Lake
Titicaca and combined isotopic data with organic biomarkers
and biogeochemical measurements. A wet period in the early
Holocene (8000-7300 BP) induced strong watershed erosion,
leading to a high HgAR (20.2 ± 6.9 μg m-2 year-1), which
exceeded the 20th century HgAR (8.4 ± 1.0 μg m-2 year-1).
Geogenic Hg input dominated during the early Holocene (fgeog
= 79%) and played a minor role during the mid- to late
Holocene (4500 BP to present; fgeog = 20%) when atmospheric
Hg deposition dominated. Sediment Δ200Hg values and the
absence of terrestrial lignin biomarkers suggest that direct
lake uptake of atmospheric Hg(0), and subsequent algal
scavenging of lake Hg, represented an important atmospheric
deposition pathway (42%) during the mid- to late Holocene.
During wet episodes of the late Holocene (2400 BP to
present), atmospheric Hg(II) deposition was the dominant
source of lake sediment Hg (up to 82%). Sediment Δ199Hg
values suggest that photochemical reduction and re-emission
of Hg(0) occurred from the lake surface. Hg stable isotopes
show promise as proxies for understanding the history of Hg
sources and transformations and help to disentangle
anthropogenic and climate factors influencing HgAR observed
in sediment archives.},
Doi = {10.1021/acsearthspacechem.1c00304},
Key = {fds362121}
}
@article{fds278641,
Author = {McGowran, B and Marty, R and Dunbar, RB and Martin, JB and Baker,
PA},
Title = {Comment on "Late Eocene diatomite from the Peruvian coastal
desert, coastal upwelling in the eastern Pacific, and
Pacific circulation before the terminal Eocene
event"},
Journal = {Geology},
Volume = {17},
Number = {10},
Pages = {957-959},
Publisher = {Geological Society of America},
Year = {1989},
Month = {January},
ISSN = {0091-7613},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:A1989AV57600022&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Doi = {10.1130/0091-7613(1989)017<0957:CAROLE>2.3.CO;2},
Key = {fds278641}
}
@article{fds278646,
Author = {Baker, PA and Kastner, M},
Title = {Constraints on the formation of sedimentary
dolomite},
Journal = {Science (New York, N.Y.)},
Volume = {213},
Number = {4504},
Pages = {214-216},
Publisher = {American Association for the Advancement of Science
(AAAS)},
Year = {1981},
Month = {January},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.213.4504.214},
Abstract = {The experimental replacement of calcite and aragonite by
dolomite under a variety of conditions indicates that
dolomitization can take place in marine and lacustrine
environments under two conditions: (i) low dissolved sulfate
concentrations and (ii) insubstantial contemporaneous silica
diagenesis. Common sites for dolomite formation are areas
where the dissolved sulfate concentration is reduced by
microbial sulfate reduction, through the mixing of seawater
with large amounts of fresh water, or where low-sulfate
alkaline lacustrine environments prevail. Even under these
conditions, dolomite formation may be inhibited by the
concurrent transformation of opal-A (amorphous silica) to
opal-CT (disordered cristobalite and tridymite), whereas the
subsequent transformation of opal-CT to quartz favors the
formation of dolomite. Copyright © 1981
AAAS.},
Doi = {10.1126/science.213.4504.214},
Key = {fds278646}
}
@article{fds278642,
Author = {Baker, PA and Weber, JN},
Title = {Coral growth rate: Variation with depth},
Journal = {Physics of the Earth and Planetary Interiors},
Volume = {10},
Number = {2},
Pages = {135-139},
Publisher = {Elsevier BV},
Year = {1975},
Month = {January},
ISSN = {0031-9201},
url = {http://dx.doi.org/10.1016/0031-9201(75)90031-X},
Abstract = {Light and temperature are two of the most important physical
factors affecting rates of growth of reef corals. The effect
of light has been determined by X-radiographic measurement
of long-term growth rates for 89 colonies of the coral
Montastrea annularis collected over a 27.5-m depth range
from St. Croix, U.S. Virgin Islands. These measurements, in
conjunction with measurements of skeletal density, have
established that M. annularis calcifies most rapidly at
intermediate depths, and they have confirmed the
identification of two distinct populations within this
important frame-building species. © 1975.},
Doi = {10.1016/0031-9201(75)90031-X},
Key = {fds278642}
}
@article{fds278643,
Author = {Baker, PA and Weber, JN},
Title = {Coral growth rate: Variation with depth},
Journal = {Earth and Planetary Science Letters},
Volume = {27},
Number = {1},
Pages = {57-61},
Publisher = {Elsevier BV},
Year = {1975},
Month = {January},
ISSN = {0012-821X},
url = {http://dx.doi.org/10.1016/0012-821X(75)90160-0},
Abstract = {Light and temperature are two of the most important physical
factors affecting rates of growth of reef corals. The effect
of light has been determined by X-radiographic measurement
of long-term growth rates for 89 colonies of the coral
Montastrea annularis collected over a 27.5-m depth range
from St. Croix, U.S. Virgin Islands. These measurements, in
conjunction with measurements of skeletal density, have
established that M. annularis calcifies most rapidly at
intermediate depths, and they have confirmed the
identification of two distinct populations within this
important frame-building species. © 1975.},
Doi = {10.1016/0012-821X(75)90160-0},
Key = {fds278643}
}
@article{fds369726,
Author = {Luethje, M and Benito, X and Schneider, T and Mosquera, PV and Baker, P and Fritz, SC},
Title = {Correction: Paleolimnological responses of Ecuadorian
páramo lakes to local and regional stressors over the last
two millennia (Journal of Paleolimnology, (2023), 69, 4,
(305-323), 10.1007/s10933-022-00274-5)},
Journal = {Journal of Paleolimnology},
Volume = {69},
Number = {4},
Pages = {325},
Year = {2023},
Month = {April},
url = {http://dx.doi.org/10.1007/s10933-023-00278-9},
Abstract = {Following the publication of the original article (Luethje
2022), the typesetters have mistakenly induced the text,
“"Melina use only…for". It should be removed in the
abstract and it should say "higher pH…". The original
article has been revised.},
Doi = {10.1007/s10933-023-00278-9},
Key = {fds369726}
}
@article{fds215102,
Author = {Jenkins HS and Baker PA},
Title = {Correlating tree growth and climate in four Peruvian tree
species},
Journal = {Earth Planet. Sci. Lett.},
Year = {2012},
Key = {fds215102}
}
@article{fds278707,
Author = {Fritz, SC and Baker, PA and Seltzer, GO and Ballantyne, A and Tapia, P and Cheng, H and Edwards, RL},
Title = {Corrigendum to "Quaternary glaciation and hydrologic
variation in the South American tropics as reconstructed
from the Lake Titicaca drilling project" [Quaternary
Research 68 (2007) 410-420] (DOI:10.1016/j.yqres.2007.07.008)},
Journal = {Quaternary Research},
Volume = {69},
Number = {2},
Pages = {342},
Publisher = {Cambridge University Press (CUP)},
Year = {2008},
Month = {March},
ISSN = {0033-5894},
url = {http://dx.doi.org/10.1016/j.yqres.2008.01.004},
Doi = {10.1016/j.yqres.2008.01.004},
Key = {fds278707}
}
@article{fds328722,
Author = {Latrubesse, EM and Arima, EY and Dunne, T and Park, E and Baker, VR and d’Horta, FM and Wight, C and Wittmann, F and Zuanon, J and Baker, PA and Ribas, CC and Norgaard, RB and Filizola, N and Ansar, A and Flyvbjerg,
B and Stevaux, JC},
Title = {Damming the Rivers of the Amazon Basin},
Journal = {Nature},
Volume = {546},
Number = {7658},
Pages = {363-369},
Year = {2017},
url = {http://dx.doi.org/10.1038/nature22333},
Abstract = {More than a hundred hydropower dams have already been built
in the Amazon basin and numerous proposals for further dam
constructions are under consideration. The accumulated
negative environmental effects of existing dams and proposed
dams, if constructed, will trigger massive hydrophysical and
biotic disturbances that will affect the Amazon basin's
floodplains, estuary and sediment plume. We introduce a Dam
Environmental Vulnerability Index to quantify the current
and potential impacts of dams in the basin. The scale of
foreseeable environmental degradation indicates the need for
collective action among nations and states to avoid
cumulative, far-reaching impacts. We suggest institutional
innovations to assess and avoid the likely impoverishment of
Amazon rivers.},
Doi = {10.1038/nature22333},
Key = {fds328722}
}
@article{fds278648,
Author = {Kennett, JP and Von Der Borch and C and Baker, PA and Barton, CE and Boersma, A and Dudley, WC and Gardner, JV and Jenkins, DG and Lohman, W and Morin, R and Martini, R and Merrill, RB and Nelson, CS and Robert, C and Srinivasan, MS and Stein, R and Takeuchi, A},
Title = {Deep-Sea Drilling Project Leg 90: The South Pacific
Cenozoic},
Journal = {Nature},
Volume = {303},
Number = {5912},
Pages = {18-19},
Publisher = {Springer Nature},
Year = {1983},
Month = {December},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/303018a0},
Doi = {10.1038/303018a0},
Key = {fds278648}
}
@article{fds278676,
Author = {Cronin, TM and Dwyer, GS and Baker, PA and Rodriguez-Lazaro, J and Briggs, WM},
Title = {Deep-sea ostracode shell chemistry (Mg:Ca ratios) and Late
Quaternary Arctic Ocean history},
Journal = {Geological Society, London, Special Publications},
Volume = {111},
Number = {1},
Pages = {117-134},
Publisher = {Geological Society of London},
Year = {1996},
Month = {December},
ISSN = {0305-8719},
url = {http://dx.doi.org/10.1144/GSL.SP.1996.111.01.08},
Abstract = {The magnesium:calcium (Mg:Ca) and strontium:calcium (Sr:Ca)
ratios were investigated in shells of the benthic ostracode
genus Krithe obtained from 64 core-tops from water depths of
73 to 4411 m in the Arctic Ocean and Nordic seas to
determine the potential of ostracode shell chemistry for
palaeoceanographic study. Shells from the Polar Surface
Water (-1 to -1.5°C) had Mg:Ca molar ratios of about
0.006-0.008; shells from Arctic Intermediate Water (+0.3 to
+2.0°C) ranged from 0.09 to 0.013. Shells from the abyssal
plain and ridges of the Nansen, Amundsen and Makarov basins
and the Norwegian and Greenland seas had a wide scatter of
Mg:Ca ratios ranging from 0.007 to 0.012 that may signify
post-mortem chemical alteration of the shells from Arctic
deep-sea environments below about 1000 m water depth. There
is a positive correlation (r2 =0.59) between Mg:Ca ratios
and bottom-water temperature in Krithe shells from Arctic
and Nordic seas from water depths <900m. Late Quaternary
Krithe Mg:Ca ratios were analysed downcore using material
from the Gakkel Ridge (water depths 3047 and 3899 m), the
Lomonosov Ridge (water depth 1051 m) and the Amundsen Basin
(water depth 4226 m) to test the core-top Mg:Ca temperature
calibration. Cores from the Gakkel and Lomonosov ridges
display a decrease in Mg:Ca ratios during the interval
spanning the last glacial/deglacial transition and the
Holocene, perhaps related to a decrease in bottom water
temperatures or other changes in benthic
environments.},
Doi = {10.1144/GSL.SP.1996.111.01.08},
Key = {fds278676}
}
@article{fds278675,
Author = {Cronin, TM and Dwyer, GS and Baker, PA and Rodriguez-Lazaro, J and Briggs, WMJ},
Title = {Deep-sea ostracode shell chemistry (Mg:Ca ratios) and late
Quaternary Arctic Ocean history},
Journal = {Late Quaternary Palaeoceanography of the North Atlantic
Margins},
Pages = {117-134},
Year = {1996},
Month = {January},
Abstract = {The magnesium:calcium (Mg:Ca) and strontium:calcium (Sr:Ca)
ratios were investigated in shells of the benthic ostracode
genus Krithe obtained from 64 core-tops from water depths of
73 to 4411 m in the Arctic Ocean and Nordic seas to
determine the potential of ostracode shell chemistry for
paleoceanographic study. Shells from the abyssal plain and
ridges of the Nansen, Amundsen and Makarov basins and the
Norwegian and Greenland seas had a wide scatter of Mg:Ca
ratios ranging from 0.007 to 0.012 that may signify
post-mortem chemical alteration of the shells from Arctic
deep-sea environments below about 1000 m water depth. There
is a positive correlation (r2=0.59) between Mg:Ca ratios and
bottom-water temperature in Krithe shells from water depths
<900 m.},
Key = {fds278675}
}
@article{fds278644,
Author = {Weber, JN and Deines, P and Weber, PH and Baker, PA},
Title = {Depth related changes in the 13C 12C
ratio of skeletal carbonate deposited by the Caribbean
reef-frame building coral Montastrea annularis: further
implications of a model for stable isotope fractionation by
scleractinian corals},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {40},
Number = {1},
Pages = {31-39},
Publisher = {Elsevier BV},
Year = {1976},
Month = {January},
ISSN = {0016-7037},
url = {http://dx.doi.org/10.1016/0016-7037(76)90191-5},
Abstract = {Systematic variations in the isotopic composition of
skeletal carbonate deposited by the Caribbean reef-frame
building coral Montastrea annularis are correlated with
water depth, location of the corallites within the corallum,
and polyp packing density, as is demonstrated by isotope
ratio measurements for 426 samples collected at 4.6 m depth
intervals between 0 and 27.4 m at St. Croix, U.S. Virgin
Islands. These data support a model, based on a study of
Indo-Pacific scleractinians, proposed earlier for stable
isotope fractionation by corals. Of particular interest is
the fact that, within this species, ecotypic differentiation
into shallow-water and deep-water subpopulations, with a
boundary close to 20m, is reflected by changes in skeletal
°13C. Stable isotope geochemical studies of both modern and
fossil coral-derived carbonate may contribute to the
solution of several problems having geologic and
paleontologic significance. © 1976.},
Doi = {10.1016/0016-7037(76)90191-5},
Key = {fds278644}
}
@article{fds278647,
Author = {Baker, PA and Gieskes, JM and Elderfield, H},
Title = {Diagenesis of carbonates in deep-sea sediments - evidence
from Sr/Ca ratios and interstitial dissolved Sr
data.},
Journal = {Journal of Sedimentary Petrology},
Volume = {52},
Number = {1},
Pages = {71-82},
Year = {1982},
Month = {January},
Abstract = {Laboratory determinations have been made of the distribution
coefficient of Sr in calcite. Chemical analyses of several
deep- sea carbonate sediment sections and their associated
porewaters demonstrate that these values are appropriate for
use in diagenetic studies. The distribution of Sr in the
pore waters and sediments has been modelled. It is concluded
that recrystallization of these carbonates is essentially
isochemical. Recrystallization of the bulk of the calcite in
deep-sea sections is largely complete within the upper few
hundred meters. These results have important implications
for the study of oxygen isotopic compositions of
foraminifers and coccoliths. A distribution coefficient of
Mg in calcite sediments has been estimated. -from Authors
distribution coefficient recrystallization isochemical
oxygen isotopic compositions},
Key = {fds278647}
}
@article{fds278655,
Author = {Gardner, JV and Nelson, CS and Baker, PA},
Title = {Distribution and character of pale green laminae in sediment
from Lord Howe Rise: a probable late Neogene and Quaternary
tephrostratigraphic record.},
Journal = {Initial Reports Dsdp, Leg 90, Noumea, New Caledonia to
Wellington, New Zealand. Part 2},
Pages = {1145-1159},
Year = {1986},
Month = {January},
url = {http://dx.doi.org/10.2973/dsdp.proc.90.125.1986},
Abstract = {The volcanic origin of the laminae is suggested by (1)
similar temporal distribution of the laminae and the
distribution of volcanic ash layers elsewhere in the
southwest Pacific; (2) the high abundances of authigenic
smectite in the laminae; and (3) the common occurrence of
iron sulfides in proximity to most of the laminae. -from
Authors},
Doi = {10.2973/dsdp.proc.90.125.1986},
Key = {fds278655}
}
@article{fds328725,
Author = {Seltzer, GO and Rodbell, DT and Baker, PA and Fritz, SC and Tapia, PM and Rowe, HD and Dunbar, RB},
Title = {Early deglaciation in the tropical Andes -
Response},
Journal = {Science (New York, N.Y.)},
Volume = {298},
Number = {5591},
Pages = {1 pages},
Publisher = {AMER ASSOC ADVANCEMENT SCIENCE},
Year = {2002},
Month = {October},
Key = {fds328725}
}
@article{fds278691,
Author = {Seltzer, GO and Rodbell, DT and Baker, PA and Fritz, SC and Tapia, PM and Rowe, HD and Dunbar, RB},
Title = {Early warming of tropical South America at the last
glacial-interglacial transition.},
Journal = {Science (New York, N.Y.)},
Volume = {296},
Number = {5573},
Pages = {1685-1686},
Year = {2002},
Month = {May},
url = {http://dx.doi.org/10.1126/science.1070136},
Abstract = {Glaciation in the humid tropical Andes is a sensitive
indicator of mean annual temperature. Here, we present
sedimentological data from lakes beyond the glacial limit in
the tropical Andes indicating that deglaciation from the
Last Glacial Maximum led substantial warming at high
northern latitudes. Deglaciation from glacial maximum
positions at Lake Titicaca, Peru/Bolivia (16 degrees S), and
Lake Junin, Peru (11 degrees S), occurred 22,000 to 19,500
calendar years before the present, several thousand years
before the Bølling-Allerød warming of the Northern
Hemisphere and deglaciation of the Sierra Nevada, United
States (36.5 degrees to 38 degrees N). The tropical Andes
deglaciated while climatic conditions remained regionally
wet, which reflects the dominant control of mean annual
temperature on tropical glaciation.},
Doi = {10.1126/science.1070136},
Key = {fds278691}
}
@article{fds358251,
Author = {Benito, X and Luethje, M and Schneider, T and Fritz, SC and Baker, PA and Pedersen, EJ and Gaüzère, P and de Novaes Nascimento and M and Bush,
M and Ruhi, A},
Title = {Ecological resilience in tropical Andean lakes: A
paleolimnological perspective},
Journal = {Limnology and Oceanography},
Volume = {67},
Number = {S1},
Pages = {S23-S37},
Year = {2022},
Month = {February},
url = {http://dx.doi.org/10.1002/lno.11747},
Abstract = {Little is known about whether changes in lake ecosystem
structure over the past 150 years are unprecedented when
considering longer timescales. Similarly, research linking
environmental stressors to lake ecological resilience has
traditionally focused on a few sentinel sites, hindering the
study of spatially synchronous changes across large areas.
Here, we studied signatures of paleolimnological resilience
by tracking change in diatom community composition over the
last 2000 years in four Ecuadorian Andean lakes with
contrasting ecoregions. We focused on climate and
anthropogenic change, and the type of biological responses
that these changes induced: gradual, elastic, or threshold.
We combined multivariate ordination techniques with
nonlinear time-series methods (hierarchical generalized
additive models) to characterize trajectories of community
responses in each lake, and coherence in such trajectories
across lakes. We hypothesized that remote, high-elevation
lakes would exhibit synchronous trends due to their shared
climatic constraints, whereas lower elevation lakes would
show less synchronous trends as a consequence of human
density and land-cover alteration. We found that gradual and
elastic responses dominated. Threshold-type responses, or
regime shifts, were only detected in the less remote lake,
after a long period of gradual and elastic changes.
Unexpected synchrony was observed in diatom assemblages from
geographically distant and human-impacted lakes, whereas
lakes under similar broad-scale environmental factors
(climate and ecoregion) showed asynchronous community
trajectories over time. Our results reveal a complex
ecological history and indicate that Andean lakes in Ecuador
can gradually adapt and recover from a myriad of
disturbances, exhibiting resilience over century to
millennial timescales.},
Doi = {10.1002/lno.11747},
Key = {fds358251}
}
@article{fds278713,
Author = {Fritz, SC and Baker, PA and Tapia, P and Spanbauer, T and Westover,
K},
Title = {Evolution of the Lake Titicaca basin and its diatom flora
over the last ~370,000 years},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {317-318},
Pages = {93-103},
Publisher = {Elsevier BV},
Year = {2012},
Month = {February},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/j.palaeo.2011.12.013},
Abstract = {In recent years, deep drilling undertaken as part of the
International Continental Drilling Program has generated
multiple long lacustrine sedimentary records to reconstruct
continental paleoclimate. In many cases, the tectonic and
geomorphic history of these basins is under-constrained and
poorly known, which affects the interpretation of climate
history from geophysical, geochemical, and paleobiotic
proxies in the sedimentary record. In addition, non-analog
biotic assemblages that reflect evolutionary processes may
constrain the reconstruction of past environments. In the
drill-core record of Lake Titicaca, spanning the last ~.
370. ka, the diatom stratigraphy reflects both the influence
of climate and the long-term evolution of the lake basin and
its biota. In the upper part of the drill-core sequence,
glacial intervals were deep and dominated by freshwater
planktic taxa, and peak interglacial intervals were shallow
and dominated by benthic species, some with saline
affinities. In the basal sections of the drill-core record,
benthic diatoms are dominant in both glacial and
interglacial units, with freshwater taxa dominating the
glacial strata. This suggests that the ancient lake basin
was shallower during intervals of both wet and dry climate,
and that the modern deep lake may result from a progressive
subsidence and deepening of the basin over time. In
addition, morphological evolution in one of the major
lineages of planktic diatoms, Cyclostephanos, indicates
substantial change in the limnological environment that
affected species morphology and may have driven speciation.
© 2011 Elsevier B.V.},
Doi = {10.1016/j.palaeo.2011.12.013},
Key = {fds278713}
}
@article{fds278667,
Author = {Zempolich, WG and Baker, PA},
Title = {Experimental and natural mimetic dolomitization of aragonite
ooids},
Journal = {Journal of Sedimentary Petrology},
Volume = {63},
Number = {4},
Pages = {596-606},
Year = {1993},
Month = {January},
Abstract = {Comparison of experimental fabrics with calcitized,
partially dolomitized and completely dolomitized aragonite
ooids of the late Proterozoic Beck Spring Dolomite indicates
that mimetic concentric fabric originates by aragonite
dissolution and early dolomite precipitation within porous
cortical laminae. Importantly, these experimental and
natural "replacement' fabrics show that fine-scale dolomite
ooid fabrics are not indicative of "primary' dolomite
precipitation. -from Authors},
Key = {fds278667}
}
@article{fds364246,
Author = {Rodrigues, FCG and Porat, N and Mineli, TD and Del Río and I and Niyonzima, P and Nogueira, L and Pupim, FDN and Silva, CG and Baker, P and Fritz, S and Wahnfried, I and Kiefer, G and Sawakuchi,
AO},
Title = {Extended-Range Luminescence Dating of Central and Eastern
Amazonia Sandy Terrains},
Journal = {Frontiers in Earth Science},
Volume = {10},
Year = {2022},
Month = {July},
url = {http://dx.doi.org/10.3389/feart.2022.888443},
Abstract = {The Amazonia biome hosts upland closed and open vegetation
ecosystems, in which the current biogeographical patterns
relate to the evolution of the physical landscape.
Therefore, understanding the origin and timing of the
substrates supporting different ecosystems is indispensable
for better comprehension of Amazonian biogeography. Here we
used quartz optically stimulated luminescence (OSL) and
thermally transferred optically stimulated luminescence
(TT-OSL) for dating sandy substrates of closed and open
vegetation environments in Central and Eastern Amazonia,
from both outcrop and drill core samples (Autazes core:
PBAT-15-43). These sandy substrates present ages ranging
from 1 ka up to almost 2 Ma, that were primarily
interpreted as depositional ages of fluvial terraces.
Moreover, ages are discussed in terms of potential
geomorphic processes leading to the formation of substrates,
such as soil mixing and apparent age of quartz from the
parent bedrock. The coupling between OSL and TT-OSL
techniques allow us to date sedimentary deposits covering
the whole Quaternary, which implies a new time window for
the Amazonia history.},
Doi = {10.3389/feart.2022.888443},
Key = {fds364246}
}
@article{fds278722,
Author = {Jenkins, HS and Baker, P and Guilderson, TP},
Title = {Extreme drought events revealed in Amazon tree ring
records},
Journal = {Geophysical Research Letters},
Year = {2009},
Key = {fds278722}
}
@article{fds278695,
Author = {Rigsby, CA and Baker, PA and Aldenderfer, MS},
Title = {Fluvial history of the Rio Ilave valley, Peru, and its
relationship to climate and human history},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {194},
Number = {1-3},
Pages = {165-185},
Publisher = {Elsevier BV},
Year = {2003},
Month = {May},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/S0031-0182(03)00276-1},
Abstract = {Fluvial strata and landforms in the Rio Ilave valley (Peru)
document a history of Holocene aggradation and downcutting
that is correlative with regional climatic events and
provides an environmental context for human occupation of
the river valley. Periods of aggradation correspond to
periods of high (or rising) level in Lake Titicaca and
elsewhere on the Altiplano, and increased sediment
accumulation in the Rio Ilave valley. Downcutting episodes
correspond to periods of low level in Lake Titicaca and low
or rapidly decreasing sedimentation rates in the Ilave
delta. There are five terrace tracts (T1 through T5) present
in this southwestern Lake Titicaca tributary. These tracts
occur as both paired and unpaired terraces and have average
heights from 1.4 to 24.3 m above the valley floor. The major
part of the fluvial sequence was deposited during the time
period from prior to the Last Glacial Maximum until about
8300 calendar years Before Present (cal BP) - a period of
generally high (but variable) precipitation on the Altiplano
and high water level in Lake Titicaca. Initial deposition
(aggradation) was followed by successive downcutting to the
T4 and T3 terrace surfaces. Initial downcutting began
immediately after precipitation, runoff, and sediment load
decreased while base level dropped. It was followed by a
period of episodic equilibrium and minor downcutting that
included a prolonged period of soil formation between ∼
8350 and 6780 cal BP. The major pulses of downcutting likely
occurred between ∼ 6000 and 4500 cal BP and were
coincident with periods of decreased precipitation on the
Altiplano and decreasing levels of Lake Titicaca. Two final
periods of infilling, resulting in deposition of the T2 and
T1 terrace sediments at ∼ 4000 to 2500 cal BP and ∼ 2000
to 1600 cal BP (during periods of rising water level in Lake
Titicaca, lacustrine sedimentation in the Rio Desaguadero
valley, and increased sedimentation offshore the Ilave
delta), were separated by brief equilibrium stages and a
brief downcutting event. This fluvial history, when coupled
with regional paleoclimatic data, relates to the region's
preceramic through Tiwanaku-period archeological records.
Archeological evidence indicates that humans occupied the
Ilave valley as early as 10 000 cal BP. The higher terraces
(T3, T4 and T5) were occupied for at least 5000 years, but
humans did not utilize the lower terraces (T1 and T2) until
after ∼ 4400-3700 cal BP. Our results confirm that these
lower terraces would not have been available for either
occupation or agriculture until after ∼ 4000 cal BP. ©
2003 Published by Elsevier Science B.V.},
Doi = {10.1016/S0031-0182(03)00276-1},
Key = {fds278695}
}
@article{fds278671,
Author = {Baker, PA and Cross, SL and Burns, SJ},
Title = {Geochemistry of carbonate nodules and cements and
implications for hydrothermal circulation, Middle Valley,
Juan de Fuca Ridge},
Journal = {Proc., Scientific Results, Odp Leg 139, Middle Valley, Juan
De Fuca Ridge},
Pages = {313-329},
Year = {1994},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.139.215.1994},
Abstract = {The chemical sources for carbonate precipitation include
alteration of basement rocks (calcium and strontium),
diffusion from seawater (magnesium), recrystallization of
biogenic calcite (calcium and carbon), oxidation of
sedimentary organic matter (carbon), and oxidation of
thermogenic methane (carbon). It is hypothesized from
chemical data that Hole 858D intersected a fault zone at 28
m below the seafloor. The fault zone is believed to be a
major conduit for the hydrothermal fluids discharging at the
nearby vent. -Authors},
Doi = {10.2973/odp.proc.sr.139.215.1994},
Key = {fds278671}
}
@article{fds278693,
Author = {Gieskes, JM and Simoneit, BRT and Shanks, WC and Goodfellow, WD and James, RH and Baker, PA and Ishibashi, JI},
Title = {Geochemistry of fluid phases and sediments: Relevance to
hydrothermal circulation in Middle Valley, ODP Legs 139 and
169},
Journal = {Applied Geochemistry},
Volume = {17},
Number = {11},
Pages = {1381-1399},
Publisher = {Elsevier BV},
Year = {2002},
Month = {November},
ISSN = {0883-2927},
url = {http://dx.doi.org/10.1016/S0883-2927(02)00108-7},
Abstract = {Geochemical and isotopic studies of pore fluids and solid
phases recovered from the Dead Dog and Bent Hill
hydrothermal sites in Middle Valley (Ocean Drilling Program
Leg 169) have been compared with similar data obtained
previously from these sites during Ocean Drilling Program
Leg 139. Although generally the hydrothermal systems reflect
non-steady state conditions, the data allow an assessment of
the history of the hydrothermal processes. Sediment K/A1
ratios as well as the distribution of anhydrite in the
sediments suggest that the Dead Dog hydrothermal field has
been, and still is, active. In contrast, similar data in the
Bent Hill hydrothermal field indicate a waning of
hydrothermal activity. Pore fluid and hydrothermal vent data
in the Dead Dog hydrothermal field are similar in nature to
the data collected during ODP Leg 139. In the area of the
Bent Hill sulfide deposit, however, the pore water data
indicate that recent wholesale flushing of the sediment
column with relatively unaltered seawater has obliterated a
previous record of hydrothermal activity in the pore fluids.
Data from the deepest part of Hole 1035A in the Bent Hill
locality show the presence of hydrothermal fluids at greater
depths in this area. This suggests the origin of the
hydrothermal fluids found to be emanating from Hole 1035F,
which constitutes one of the first man made hydrothermal
vents in the Middle Valley hydrothermal system. Similarly,
CORKed Hole 858G, because of seal failures, has acted as a
hydrothermal vent, with sulfide deposits forming inside the
CORK. © 2002 Elsevier Science Ltd. All rights
reserved.},
Doi = {10.1016/S0883-2927(02)00108-7},
Key = {fds278693}
}
@article{fds278661,
Author = {Malone, MJ and Baker, PA and Burns, SJ and Swart,
PK},
Title = {Geochemistry of periplatform carbonate sediments, Leg 115,
Site 716 Maldives Archipelago, (Indian Ocean)},
Journal = {Proc., Scientific Results, Odp, Leg 115, Mascarene
Plateau},
Pages = {647-659},
Year = {1990},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.115.184.1991},
Abstract = {Site 716 is a continuous sequence (upper Miocene to
Holocene) of periplatform oozes and chalks from the Maldives
Ridge, Indian Ocean. Mineralogical and geochemical studies
of these carbonate sediments indicate that submarine burial
diagenesis has played an important role in the induration of
sediments at this site. Metastable carbonates,
high-magnesium calcite (HMC) and aragonite, convert to
low-maganesium calcite (LMC) rapidly, within 1.1 and 6.0 Ma,
respectively. Positive shifts in oxygen isotopic composition
record episodes of cementation during burial diagenesis.
Intervals with increased accumulation rates of metastable
components have undergone more rapid diagenesis than
intervals with predominantly pelagic deposition. -from
Authors},
Doi = {10.2973/odp.proc.sr.115.184.1991},
Key = {fds278661}
}
@article{fds278663,
Author = {Burns, SJ and Swart, PK and Baker, PA},
Title = {Geochemistry of secondary carbonates in Leg 115 basalts:
tracers of basalt/seawater interaction},
Journal = {Proc., Scientific Results, Odp, Leg 115, Mascarene
Plateau},
Pages = {93-101},
Year = {1990},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.115.183.1990},
Abstract = {This report presents the results of a study of the stable
isotopic and chemical composition of secondary carbonate
minerals precipitated within basalts at Ocean Drilling
Program Sites 707 and 715. The geochemistry of Site 715
samples indicates that they precipitated from
seawater-dominated fluids, at low temperatures, as is
typical of secondary carbonates from most Deep Sea Drilling
Project sites. Site 707 carbonates precipitated at low
temperatures in a fairly closed system, in which
basalt-seawater interaction has greatly influenced the
chemistry of the pore fluids. The reactions occurring within
the system before and in conjunction with secondary
carbonate precipitation include oxidation of isotopically
light methane, derived from fluids circulating within the
basalts, and reduction of substantial amounts of iron and
manganese oxides from the basalts. -from
Authors},
Doi = {10.2973/odp.proc.sr.115.183.1990},
Key = {fds278663}
}
@article{fds278715,
Author = {Craig, N and Aldenderfer, M and Rigsby, C and Baker, P and Flores,
L},
Title = {Geologic constraints on a form of sustainable agriculture: a
remote sensing inventory of rain fed q'ocha agricultural
infrastructure, northern Lake Titicaca Basin,
Peru},
Journal = {Latin American Antiquity},
Year = {2010},
Key = {fds278715}
}
@article{fds278711,
Author = {Craig, N and Aldenderfer, MS and Rigsby, CA and Baker, PA and Blanco,
LF},
Title = {Geologic constraints on rain-fed Qocha reservoir
agricultural infrastructure, northern Lake Titicaca Basin,
Peru},
Journal = {Journal of Archaeological Science},
Volume = {38},
Number = {11},
Pages = {2897-2907},
Publisher = {Elsevier BV},
Year = {2011},
Month = {January},
ISSN = {0305-4403},
url = {http://dx.doi.org/10.1016/j.jas.2011.05.005},
Abstract = {This paper reports new data on qocha ponds from the Rio
Pucara-Azángaro interfluvial zone, northern Lake Titicaca
Basin, Peru. Qocha are a little known form of Andean
agriculture that developed around 800-500 B.C. and remain in
use today. Prior estimates suggested that in the study area,
there were more than 25,000 qocha. While most Andean sunken
beds are excavated to reach groundwater, qocha are rain-fed
ponds. How these rain-fed ponds functioned has been an open
question, but one that is answered in part by research
presented in this paper. We suggest that a thick impermeable
stratum of clay that was possibly deposited by paleolake
"Minchin" created a perched water table that makes rain-fed
qocha reservoir agriculture possible. Field geology shows
that within the study area, this stratum only exists under
Terrace E. Based on this model, we hypothesized that
persistently used qocha should only be found on Terrace E.
To test this hypothesis we used remotely sensed data to
inventory qocha and to determine their distribution by each
terrace present. We identified 11,737 qocha. By area 93.77%
and by count 94.33% of the qocha are located on Terrace E.
These results strongly supported our hypothesis. This case
study illustrates that the long term viability of this form
of agriculture is made possible by a physical context that
is beyond human control. © 2011 Elsevier
Ltd.},
Doi = {10.1016/j.jas.2011.05.005},
Key = {fds278711}
}
@article{fds278709,
Author = {Latrubesse, EM and Baker, PA and Argollo, J},
Title = {Geomorphology of Natural Hazards and Human-induced Disasters
in Bolivia},
Journal = {Developments in Earth Surface Processes},
Volume = {13},
Number = {C},
Pages = {181-194},
Booktitle = {Geomorphology of Natural Hazards and Human-Exacerbated
Disasters in Latin America,},
Publisher = {Elsevier},
Year = {2009},
Month = {December},
ISSN = {0928-2025},
url = {http://dx.doi.org/10.1016/S0928-2025(08)10010-4},
Abstract = {Bolivia is a large and diverse nation in its geography, its
culture, and its economy. Poverty levels are high throughout
the nation, with a large part of the population having only
limited access to essential services, including education,
health, and sound housing. In 2007, Bolivia was ranked 117th
out of 177 countries on the Human Development Index, a
standardized measure combining life expectancy, literacy,
education, and overall standard of living (UNDP, 2007). This
is the third lowest index in the Western Hemisphere. Because
of these socioeconomic conditions, Bolivia is highly
vulnerable to hazards, both natural and man-made. The
political, economic, and physical geography of Bolivia has
been thoroughly reviewed by Montes de Oca (1997). Although
Bolivia is in a tectonically and volcanically active region,
neither seismic nor volcanic events have historically
produced as large an impact (measured by total loss of life
or livelihood) as have hydrometeorological events, including
floods, landslides, droughts, and frost. Climate change is
predicted to increase future temperatures in all parts of
the nation, further accelerating the loss of mountain
glaciers and snowpack and exacerbating the impact of drought
in semiarid agricultural regions. Predictions of future
precipitation changes vary according to the particular
climate model, but the most robust result points to a
possible increase in the intensity of wet-season
precipitation (more wet days per year) over large parts of
Amazonia and southern South America (IPCC, 2007, p. 896).
The latter would increase the flooding hazard of much of
lowland Bolivia that has already been subjected to
widespread flooding for the past three years (2006-2008). ©
2010 Elsevier B.V. All rights reserved.},
Doi = {10.1016/S0928-2025(08)10010-4},
Key = {fds278709}
}
@article{fds278718,
Author = {Clark, and U, P and Shakun, and D, J and Baker, and A, P and others},
Title = {Global climate evolution during the last
deglaciation},
Journal = {Science},
Volume = {109},
Number = {19},
Pages = {E1134-E1142},
Year = {2010},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.1116619109},
Abstract = {Deciphering the evolution of global climate from the end of
the Last Glacial Maximum approximately 19 ka to the early
Holocene 11 ka presents an outstanding opportunity for
understanding the transient response of Earth's climate
system to external and internal forcings. During this
interval of global warming, the decay of ice sheets caused
global mean sea level to rise by approximately 80 m;
terrestrial and marine ecosystems experienced large
disturbances and range shifts; perturbations to the carbon
cycle resulted in a net release of the greenhouse gases
CO(2) and CH(4) to the atmosphere; and changes in atmosphere
and ocean circulation affected the global distribution and
fluxes of water and heat. Here we summarize a major effort
by the paleoclimate research community to characterize these
changes through the development of well-dated,
high-resolution records of the deep and intermediate ocean
as well as surface climate. Our synthesis indicates that the
superposition of two modes explains much of the variability
in regional and global climate during the last deglaciation,
with a strong association between the first mode and
variations in greenhouse gases, and between the second mode
and variations in the Atlantic meridional overturning
circulation.},
Doi = {10.1073/pnas.1116619109},
Key = {fds278718}
}
@article{fds278639,
Author = {Seltzer, GO and Baker, P and Cross, S and Dunbar, R and Fritz,
S},
Title = {High-resolution seismic reflection profiles from Lake
Titicaca, Peru-Bolivia: Evidence for Holocene aridity in the
tropical Andes},
Journal = {Geology},
Volume = {26},
Number = {2},
Pages = {167-170},
Year = {1998},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/0091-7613(1998)026<0167:HRSRPF>2.3.CO},
Abstract = {High-resolution seismic reflection profiles of the sediments
of Lake Titicaca, Peru-Bolivia, suggest that lake levels in
the recent past were considerahly lower than today. Incised
channels on the major deltas extend to depths of 85 m below
modern lake level. Erosional truncation of onlapping seismic
reflectors is found at similar depths. This interpretation
of the seismic data is supported by analyses of sediment
cores from the lake, which indicate that there was a
significant drop in lake level during the early to
mid-Holocene.},
Doi = {10.1130/0091-7613(1998)026<0167:HRSRPF>2.3.CO},
Key = {fds278639}
}
@article{fds278703,
Author = {Baker, PA and Fritz, SC and Garland, J and Ekdahl,
E},
Title = {Holocene hydrologic variation at Lake Titicaca,
Bolivia/Peru, and its relationship to North Atlantic climate
variation},
Journal = {Journal of Quaternary Science},
Volume = {20},
Number = {7-8},
Pages = {655-662},
Publisher = {WILEY},
Year = {2005},
Month = {October},
ISSN = {0267-8179},
url = {http://dx.doi.org/10.1002/jqs.987},
Abstract = {A growing number of sites in the Northern Hemisphere show
centennial- to millennial-scale climate variation that has
been correlated with change in solar variability or with
change in North Atlantic circulation. However, it is unclear
how (or whether) these oscillations in the climate system
are manifest in the Southern Hemisphere because of a lack of
sites with suitably high sampling resolution. In this paper,
we reconstruct the lake-level history of Lake Titicaca,
using the carbon isotopic content of sedimentary organic
matter, to evaluate centennial- to millennial-scale
precipitation variation and its phasing relative to sites in
the Northern Hemisphere. The pattern and timing of
lake-level change in Lake Titicaca is similar to the
ice-rafted debris record of Holocene Bond events,
demonstrating a possible coupling between precipitation
variation on the Altiplano and North Atlantic sea-surface
temperatures (SSTs). The cold periods of the Holocene Bond
events correspond with periods of increased precipitation on
the Altiplano. Holocene precipitation variability on the
Altiplano is anti-phased with respect to precipitation in
the Northern Hemisphere monsoon region. More generally, the
tropical Andes underwent large changes in precipitation on
centennial-to-millennial timescales during the Holocene.
Copyright © 2005 John Wiley & Sons, Ltd.},
Doi = {10.1002/jqs.987},
Key = {fds278703}
}
@article{fds278708,
Author = {Ekdahl, EJ and Fritz, SC and Baker, PA and Rigsby, CA and Coley,
K},
Title = {Holocene multidecadal- to millennial-scale hydrologic
variability on the South American Altiplano},
Journal = {The Holocene},
Volume = {18},
Number = {6},
Pages = {867-876},
Publisher = {SAGE Publications},
Year = {2008},
Month = {September},
ISSN = {0959-6836},
url = {http://dx.doi.org/10.1177/0959683608093524},
Abstract = {Precipitation on the South American Altiplano varies at a
range of temporal scales. A long-term secular increase in
moisture availability from the early/mid Holocene to the
present, driven by increasing summer insolation resulting
from precessional changes in the Earth's orbit, has been
documented in earlier studies. However, higher frequency
Holocene variability is not yet understood. Here we present
high-resolution diatom assemblage data from two small
Altiplano lakes, Lago Lagunillas and Lago Umayo, indicating
changes in effective moisture in the southern tropical Andes
at decadal, centennial and millennial timescales throughout
the mid to late Holocene. A strong millennial-scale
component, similar in pacing to periods of increased
ice-rafted debris flux in the North Atlantic, is observed in
both lake records, which suggests that regional
precipitation and North Atlantic climate variability are
coupled at these scales. The interpretation of the higher
frequency variability is hampered by the small number of
high-resolution continental and marine records for
comparison. © 2008 SAGE Publications.},
Doi = {10.1177/0959683608093524},
Key = {fds278708}
}
@article{fds278719,
Author = {Toney, J and Huang, Y and Fritz, SC and Baker, PA and Grimm, EC and Nyren,
PE},
Title = {Holocene spring temperature in the Northern Great Plains,
U.S and shifting boundary conditions},
Journal = {Geology},
Year = {2010},
Key = {fds278719}
}
@article{fds278699,
Author = {Fritz, SC and Baker, PA and Lowenstein, TK and Seltzer, GO and Rigsby,
CA and Dwyer, GS and Tapia, PM and Arnold, KK and Ku, TL and Luo,
S},
Title = {Hydrologic variation during the last 170,000 years in the
southern hemisphere tropics of South America},
Journal = {Quaternary Research},
Volume = {61},
Number = {1},
Pages = {95-104},
Publisher = {Cambridge University Press (CUP)},
Year = {2004},
Month = {January},
ISSN = {0033-5894},
url = {http://hdl.handle.net/10161/6625 Duke open
access},
Abstract = {Despite the hypothesized importance of the tropics in the
global climate system, few tropical paleoclimatic records
extend to periods earlier than the last glacial maximum
(LGM), about 20,000 years before present. We present a
well-dated 170,000-year time series of hydrologic variation
from the southern hemisphere tropics of South America that
extends from modern times through most of the penultimate
glacial period. Alternating mud and salt units in a core
from Salar de Uyuni, Bolivia reflect alternations between
wet and dry periods. The most striking feature of the
sequence is that the duration of paleolakes increased in the
late Quaternary. This change may reflect increased
precipitation, geomorphic or tectonic processes that
affected basin hydrology, or some combination of both. The
dominance of salt between 170,000 and 140,000 yr ago
indicates that much of the penultimate glacial period was
dry, in contrast to wet conditions in the LGM. Our analyses
also suggest that the relative influence of insolation
forcing on regional moisture budgets may have been stronger
during the past 50,000 years than in earlier times. © 2003
University of Washington. All rights reserved.},
Doi = {10.1016/j.yqres.2003.08.007},
Key = {fds278699}
}
@article{fds278678,
Author = {Malone, MJ and Baker, PA and Burns, SJ},
Title = {Hydrothermal dolomitization and recrystallization of
dolomite breccias from the Miocene Monterey formation,
Tepusquet area, California},
Journal = {Journal of Sedimentary Research},
Volume = {66},
Number = {5},
Pages = {976-990},
Publisher = {Society for Sedimentary Geology},
Year = {1996},
Month = {September},
ISSN = {1527-1404},
url = {http://dx.doi.org/10.1306/D426845A-2B26-11D7-8648000102C1865D},
Abstract = {Dolomite breccias from the Miocene Monterey Formation,
Tepusquet area, California are composed of dolomitic
siliceous mudstones that are extensively fractured and
filled with white, coarse-grained saddle dolomites.
Fracturing and brecciation are much more extensive and
intense in the Tepusquet area than in most other outcrops of
the Monterey Formation. Despite the intensity of brecciation
and its potential importance as an analog to Monterey
fractured hydrocarbon reservoirs, no detailed petrographic,
cristallographic, or geochemical analyses have been
performed on the breccias from the Tepusquet area. In the
present study, petrographic, crystallographic, and
geochemical analyses show that the vein-filling dolomites
were precipitated from hydrothermal fluids that were
associated with hydrocarbon migration, and that the early
diagenetic matrix dolomites have been recrystallized,
resetting their geochemical and crystallographic properties.
Recrystallization of matrix dolomites is indicated by the
uniformly negative β 18O compositions (x̄ = -7.1‰), low
Sr contents (x̄ = 230 ppm), low Na contents (x̄ = 364
ppm), contracted unit cells (x̄: a = 4.812 Å, c = 16.058
Å), high degree of cation order, high Mg content (x̄ =
46.1 mol% MgCO 3) as compared to most Monterey dolomites,
and increasing 87Sr/ 86Sr ratios with decreasing Sr content.
Vein dolomites have large variation in stoichiometry
(41.7-49.0 mol% MgCO 3), Sr content (124-414 ppm), unit-cell
dimensions (a: 4.806-4.829 Å, c: 16.013-16.178 Å), and
cation order (Ca site occupancy: 0.73-0.93, Mg site:
0.68-0.94). Recrystallization of some vein dolomites is
indicated by the covariance of mol% MgCO 3 with Sr, δ 18O,
cation order, and unit-cell parameters. The covariance of δ
18O with mol% MgCO 3 is the inverse of the trend expected
for the recrystallization of dolomite during burial
diagenesis, possibly because of recrystallization during
up-lift. Vein dolomites have higher 87Sr/ 86Sr values than
matrix dolomites. The least radiogenic matrix dolomites (the
least recrystallized as inferred from the δ 18O
composition) have 87Sr/ 86Sr apparent ages (13.0 and 15.5 Ma
± 0.3) that agree well with the previously mapped age of
the brecciated unit. The more recrystallized matrix
dolomites have higher 87Sr/ 86Sr ratios (apparent ages too
young for the lower Monterey Formation), thus recording the
evolution of Sr isotopic composition of the pore fluid. The
close chemical similarity of the vein dolomites and the most
recrystallized matrix dolomites, the episodic association
between hydrocarbons and the vein dolomites, and the
recrystallization trends in the matrix dolomites, all
indicate that evolved formation waters were the source of
the hydrothermal fluids that precipitated the vein
dolomites.},
Doi = {10.1306/D426845A-2B26-11D7-8648000102C1865D},
Key = {fds278678}
}
@article{fds278692,
Author = {Gieskes, JM and Simoneit, BRT and Goodfellow, WD and Baker, PA and Mahn,
C},
Title = {Hydrothermal geochemistry of sediments and pore waters in
Escanaba Trough - ODP Leg 169},
Journal = {Applied Geochemistry},
Volume = {17},
Number = {11},
Pages = {1435-1456},
Publisher = {Elsevier BV},
Year = {2002},
Month = {November},
ISSN = {0883-2927},
url = {http://dx.doi.org/10.1016/S0883-2927(02)00111-7},
Abstract = {Geochemical studies of pore fluids and solid phases in two
Ocean Drilling Program (ODP) drill sites (Sites 1037 and
1038) in the Escanaba Trough off Northern California have
provided further data on the hydrothermal processes
associated with the spreading of the Gorda Ridge. Previous
work in the area of ODP Site 1038 includes the discovery of
a hydrothermal system and associated sulfide deposits
centered around an uplifted sediment hill in this sedimented
extensional environment. This earlier work provided some
insights into the present nature of venting; however, only
deep drilling investigations can provide the means to fully
understand the genesis and evolution of this system and
associated hydrothermal deposits. ODP Leg 169 is the third
deep drilling operation to explore the magnitude, genesis,
and evolution of hydrothermal systems on sedimented ridges.
Previous studies centered on the Guaymas Basin in the Gulf
of California and the Middle Valley in the NE Pacific Ocean.
Pore water studies in the reference ODP Site 1037 and in the
hydrothermally active area of ODP Site 1038 have revealed
the presence of a complex system of hydrothermally
originated fluids. Whereas the data in the reference site
indicate recent hydrothermal activity in the basal part of
the drill site, the evidence in Site 1038 suggests that
fluids of hydrothermal origin spread out at shallow depths
around the central hill, causing substantial sediment
alteration as well as deposition of hydrothermal sulfides in
the near surface zone of the sediments. A second major
discovery at Site 1038 was the evidence for fluid phase
separation at depth at temperatures possibly in excess of
400°C. This conclusion is based on the presence of both low
Cl and high Cl fluids. The latter appear to be advected
rapidly towards the surface, presumably along cracks and
faults. The low Cl fluids, however, appear to be transported
laterally along sandy horizons in the sediments, thus
signifying two very different migration pathways for high Cl
and low Cl hydrothermally phase separated fluids. Studies of
the organic geochemistry of dissolved gases and matured
organic matter corroborate these findings of extensive
hydrothermal alteration of the sediments. © 2002 Elsevier
Science Ltd. All rights reserved.},
Doi = {10.1016/S0883-2927(02)00111-7},
Key = {fds278692}
}
@article{fds278710,
Author = {Li, W and Zhang, P and Ye, J and Li, L and Baker, PA},
Title = {Impact of two different types of El Niño events on the
Amazon climate and ecosystem productivity},
Journal = {Journal of Plant Ecology},
Volume = {4},
Number = {1-2},
Pages = {91-99},
Publisher = {Oxford University Press (OUP)},
Year = {2011},
ISSN = {1752-9921},
url = {http://dx.doi.org/10.1093/jpe/rtq039},
Abstract = {Aims The Amazon basin plays an important role in the global
carbon budget. Interannual climate variability associated
with El Niño can affect the Amazon ecosystem carbon
balance. In recent years, studies have suggested that there
are two different types of El Ninos: eastern-Pacific (EP) El
Niño and central-Pacific (CP) El Niño. The impacts of two
types of El Niño on the Amazon climate and Amazon ecosystem
are analyzed in the study. Methods A composite method has
been applied to highlight the common features for the EP-
and CP-El Niño events using observational data, IPCC-AR4
model output. Potential impacts of the two different types
of El Niño on ecosystem carbon sequestration over the
Amazon have been investigated using a process-based
biogeochemical model, the Biome-BioGeochemical Cycles model
(Biome-BGC). Important Findings Below-normal rainfall is
observed year round in northern, central and eastern
Amazonia during EP-El Niño years. During CP-El Niño years,
negative rainfall anomalies are observed in most of the
Amazon during the austral summer wet season, while there is
average or above-average precipitation in other seasons. EP-
and CP-El Niño events produce strikingly different
precipitation anomaly pattern in the tropical and
subtropical Andes during the austral fall season: wetter
conditions prevail during EP-El Niño years and drier
conditions during CP-El Niño years. Temperatures are
above-average year round throughout tropical South America
during EP-El Niño events, especially during austral summer.
During CP-El Niño events, average or slightly above-average
temperatures prevail in the tropics, but these temperatures
are less extreme than EP year's temperature except in
austral fall. These precipitation and temperature anomalies
influence ecosystem productivity and carbon sequestration
throughout the Amazon. Using the Biome-BGC model, we find
that net ecosystem production (NEP) in the EP-El Niño years
is below average, in agreement with most previous studies;
such results indicate that the Amazon region acts as a net
carbon source to the atmosphere during EP-El Niño years. In
the CP-El Niño years, NEP does not differ significantly
from its climatological value, suggesting that the Amazon
forest remains a carbon sink for the atmosphere. Thus, even
if CP-El Niño events increase in frequency or amplitude
under global warming climate as predicted in some Global
Climate Models, the Amazon rainforest may remain a carbon
sink to the atmosphere during El Niño years in the near
future. © The Author 2011. Published by Oxford University
Press on behalf of the Institute of Botany, Chinese Academy
of Sciences and the Botanical Society of
China.},
Doi = {10.1093/jpe/rtq039},
Key = {fds278710}
}
@article{fds278720,
Author = {Li, W and Zhang, P and Ye, J and Li, L and Baker, P},
Title = {Impacts of the two types of El Nino Events on the Amazon
forest},
Journal = {Journal of Plant Ecology},
Year = {2010},
Key = {fds278720}
}
@article{fds278688,
Author = {Rowe, HD and Dunbar, RB and Mucciarone, DA and Seltzer, GO and Baker,
PA and Fritz, S},
Title = {Insolation, moisture balance and climate change on the South
American Altiplano since the Last Glacial
Maximum},
Journal = {Climatic Change},
Volume = {52},
Number = {1-2},
Pages = {175-199},
Year = {2002},
Month = {February},
ISSN = {0165-0009},
url = {http://dx.doi.org/10.1023/A:1013090912424},
Abstract = {Sediment cores from Lake Titicaca contain proxy records of
past lake level and hydrologic change on the South American
Altiplano. Large downcore shifts in the isotopic composition
of organic carbon, C/N, wt. %Corg, %CaCO3, and % biogenic
silica illustrate the dynamic changes in lake level that
occurred during the past 20,000 years. The first cores taken
from water depths greater than 50 meters in the northern
subbasin of the lake are used to develop and extend the
paleolake-level record back to the Last Glacial Maximum
(LGM). Quantitative estimates of lake level are developed
using transfer functions based on the δ13C of modern
lacustrine organic sources and the δ13C of modern
sedimented organic matter from core-tops. Lake level was
slightly higher than modern during much of the post-LGM
(20,000-13,500 yr BP) and lake water was fresh under the
associated outflow conditions. The Pleistocene/Holocene
transition (13,500-7,500 yr BP) was a period of gradual
regression, punctuated by minor trangressions. Following a
brief highstand at about 7250 yr BP, lake level dropped
rapidly to 85 m below the modern level, reaching maximum
lowstand conditions by 6250 yr BP. Lake level increased
rapidly between 5000 yr BP and 4000 yr BP, and less rapidly
between 4000 yr BP and 1500 yr BP. Lake level remained
relatively high throughout the latest Holocene with only
minor fluctuations (< 12 meters). Orbitally induced changes
in solar insolation, coupled with long-term changes in El
Niño-Southern Oscillation variability, are the most likely
driving forces behind millennial-scale shifts in lake level
that reflect regional-scale changes in the moisture balance
of the Atlantic-Amazon-Altiplano hydrologic
system.},
Doi = {10.1023/A:1013090912424},
Key = {fds278688}
}
@article{fds336120,
Author = {Marsh, EJ and Bruno, MC and Fritz, SC and Baker, P and Capriles, JM and Hastorf, CA},
Title = {IntCal, SHCal, or a Mixed Curve? Choosing a 14C
Calibration Curve for Archaeological and Paleoenvironmental
Records from Tropical South America},
Journal = {Radiocarbon},
Volume = {60},
Number = {3},
Pages = {925-940},
Publisher = {Cambridge University Press (CUP)},
Year = {2018},
Month = {June},
url = {http://dx.doi.org/10.1017/RDC.2018.16},
Abstract = {Because the 14C calibration curves IntCal and SHCal are
based on data from temperate latitudes, it remains unclear
which curve is more suitable for archaeological and
paleoenvironmental records from tropical South America. A
review of climate dynamics reveals a significant influx of
Northern Hemisphere air masses and moisture over a
substantial part of the continent during the South American
Summer Monsoon (SASM). Areas affected by the SASM receive
unknown amounts of input from both hemispheres, where an
argument could be made for either curve. Until localized
tree-ring data can resolve this, we suggest using a mixed
calibration curve, which accounts for inputs from both
hemispheres, as a third calibration option. We present a
calibration example from a crucial period of environmental
and cultural change in the southern Lake Titicaca. Given our
current lack of data on past14C variation in South America,
our calibrations and chronologies will likely change in the
future. We hope this paper spurs new research into this
topic and encourages researchers to make an informed and
explicit choice of which curve to use, which is particularly
relevant in research on past human-environmental
relationships.},
Doi = {10.1017/RDC.2018.16},
Key = {fds336120}
}
@article{fds278684,
Author = {Baker, PA and Fritz, SC and Seltzer, GO},
Title = {Lake Titicaca: An archive of South American
paleoclimate},
Journal = {Geotimes},
Volume = {46},
Number = {12},
Pages = {20-21},
Year = {2001},
Month = {December},
ISSN = {0016-8556},
Key = {fds278684}
}
@article{fds278664,
Author = {Baker, PA and Stout, PM and Kastner, M and Elderfield,
H},
Title = {Large-scale lateral advection of seawater through oceanic
crust in the central equatorial Pacific},
Journal = {Earth and Planetary Science Letters},
Volume = {105},
Number = {4},
Pages = {522-533},
Publisher = {Elsevier BV},
Year = {1991},
Month = {January},
ISSN = {0012-821X},
url = {http://dx.doi.org/10.1016/0012-821X(91)90189-O},
Abstract = {The existence of large-scale lateral advection of water
through basaltic crust in the central equatorial Pacific
Ocean is demonstrated by the calcium, magnesium, strontium,
sulfate, and strontium isotopic compositions of pore waters
from the overlying sediments. The advection is believed to
extend throughout the region of the equatorial
high-productivity sediment bulge from about 110 to 160°W
and from about 5°S to 8°N. The corresponding crustal ages
of this region vary from east to west from about 15 to about
70 Ma, respectively. This advection is responsible for the
low-conductive heat flows previously observed throughout the
region. The flow is recognized by the following
characteristic pore water compositional variations. Calcium
and magnesium concentrations remain nearly constant downhole
from the sediment-water interface to basement. Species, such
as strontium, sulfate, and strontium isotopes, which are
more affected by diagenetic reactions in the sediment
column, depart from seawater values with increasing depth in
the sediments, but then they display concentration reversals
near basement. At the sediment-basement interface, pore
waters are chemically and isotopically nearly
indistinguishable from present-day seawater. Fluid flow in
basement is rapid, having a calculated average residence
time in oceanic crust of about 20,000 years and an inferred
pore fluid velocity between 1 and 10 m y-1. Because of the
short reaction time between basement rocks and fluids, as
well as the low temperature of this fluid, the chemistry of
basement water remains similar to seawater. As a result,
despite the important impact of this process on oceanic heat
flow, the flow may have little effect on the long-term major
element composition of seawater. © 1991.},
Doi = {10.1016/0012-821X(91)90189-O},
Key = {fds278664}
}
@article{fds278640,
Author = {Baker, PA and Bush, M and Fritz, S and Rigsby, CA and Seltzer, G and Silman, M},
Title = {Last Glacial Maximum in an Andean cloud forest environment
(Eastern Cordillera, Bolivia): Comment},
Journal = {Geology},
Volume = {31},
Number = {1},
Pages = {e26-e27},
Publisher = {Geological Society of America},
Year = {2003},
Month = {January},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/0091-7613-31.1.e26},
Doi = {10.1130/0091-7613-31.1.e26},
Key = {fds278640}
}
@article{fds278637,
Author = {Marty, R and Dunbar, R and Martin, JB and Baker, P},
Title = {Late Eocene diatomite from the Peruvian coastal desert,
coastal upwelling in the eastern Pacific, and Pacific
circulation before the terminal Eocene event},
Journal = {Geology},
Volume = {16},
Number = {9},
Pages = {819-822},
Year = {1988},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/0091-7613(1988)?016<0818:LEDFTP>?2.3.CO},
Abstract = {Previously undocumented late Eocene diatomaceous sediments
are present near Fundo Desbarrancado (FD) in southern Peru.
These sediments are similar to Miocene diatomite from the
same area but, unlike the Miocene diatomite, the FD
sediments contain cherty layers, are enriched in CaCO3, have
a diverse and abundant radiolarian fauna, and possess
varved-massive and millimetre- and metre-scale
biogenic-terrigenous alternations. The FD sediments are part
of an Eocene sequence that includes the clastic sediments of
the Paracas Formation, and they are correlative to the Chira
Formation of northern Peru. The Paleogene biogenic sediments
of western South America show that coastal upwelling
developed in the eastern Pacific before the latest Eocene,
argue for the existence of a proto-Humboldt current at this
time, and suggest that the terminal Eocene event was the
culmination of gradual changes and not a catastrophic event
at the Eocene/Oligocene boundary. -Authors},
Doi = {10.1130/0091-7613(1988)?016<0818:LEDFTP>?2.3.CO},
Key = {fds278637}
}
@article{fds278657,
Author = {Marty, R and Dunbar, R and Martin, JB and Baker, P},
Title = {Late Eocene diatomite from the Peruvian coastal desert,
coastal upwelling in the eastern Pacific, and Pacific
circulation before the terminal Eocene event},
Journal = {Geology},
Volume = {16},
Number = {9},
Pages = {818-822},
Publisher = {Geological Society of America},
Year = {1988},
ISSN = {0091-7613},
url = {http://dx.doi.org/10.1130/0091-7613(1988)016<0818:LEDFTP>2.3.CO;2},
Abstract = {Previously undocumented late Eocene diatomaceous sediments
are present near Fundo Desbarrancado (FD) in southern Peru.
These sediments are similar to Miocene diatomite from the
same area but, unlike the Miocene diatomite, the FD
sediments contain cherty layers, are enriched in CaCO3, have
a diverse and abundant radiolarian fauna, and possess
varved-massive and millimetre- and metre-scale
biogenic-terrigenous alternations. The FD sediments are part
of an Eocene sequence that includes the clastic sediments of
the Paracas Formation, and they are correlative to the Chira
Formation of northern Peru. The Paleogene biogenic sediments
of western South America show that coastal upwelling
developed in the eastern Pacific before the latest Eocene,
argue for the existence of a proto-Humboldt current at this
time, and suggest that the terminal Eocene event was the
culmination of gradual changes and not a catastrophic event
at the Eocene/Oligocene boundary. © 1988 Geological Society
of America.},
Doi = {10.1130/0091-7613(1988)016<0818:LEDFTP>2.3.CO;2},
Key = {fds278657}
}
@article{fds341716,
Author = {Guédron, S and Tolu, J and Brisset, E and Sabatier, P and Perrot, V and Bouchet, S and Develle, AL and Bindler, R and Cossa, D and Fritz, SC and Baker, PA},
Title = {Late Holocene volcanic and anthropogenic mercury deposition
in the western Central Andes (Lake Chungará,
Chile).},
Journal = {The Science of the Total Environment},
Volume = {662},
Pages = {903-914},
Year = {2019},
Month = {April},
url = {http://dx.doi.org/10.1016/j.scitotenv.2019.01.294},
Abstract = {Volcanism is one of the major natural processes emitting
mercury (Hg) to the atmosphere, representing a significant
component of the global Hg budget. The importance of
volcanic eruptions for local-scale Hg deposition was
investigated using analyses of Hg, inorganic elemental
tracers, and organic biomarkers in a sediment sequence from
Lake Chungará (4520 m a.s.l.). Environmental change and
Hg deposition in the immediate vicinity of the Parinacota
volcano were reconstructed over the last 2700 years,
encompassing the pre-anthropogenic and anthropogenic
periods. Twenty eruptions delivering large amounts of Hg (1
to 457 μg Hg m-2 yr-1 deposited at the timescale of
the event) were locally recorded. Peaks of Hg concentration
recorded after most of the eruptions were attributed to a
decrease in sedimentation rate together with the rapid
re-oxidation of gaseous elemental Hg and deposition with
fine particles and incorporation into lake primary
producers. Over the study period, the contribution of
volcanic emissions has been estimated as 32% of the total Hg
input to the lake. Sharp depletions in primary production
occurred at each eruption, likely resulting from massive
volcaniclastic inputs and changes in the lake-water
physico-chemistry. Excluding the volcanic deposition
periods, Hg accumulation rates rose from natural background
values (1.9 ± 0.5 μg m-2 yr-1) by a factor of
2.3 during the pre-colonial mining period
(1400-900 yr cal. BP), and by a factor of 6 and 7.6,
respectively, during the Hispanic colonial epoch
(400-150 yr cal. BP) and the industrial era
(~140 yr cal. BP to present). Altogether, the dataset
indicates that lake primary production has been the main,
but not limiting, carrier for Hg to the sediment. Volcanic
activity and climate change are only secondary drivers of
local Hg deposition relative to the magnitude of regional
and global anthropogenic emissions.},
Doi = {10.1016/j.scitotenv.2019.01.294},
Key = {fds341716}
}
@article{fds278685,
Author = {Cross, SL and Baker, PA and Seltzer, GO and Fritz, SC and Dunbar,
RB},
Title = {Late quaternary climate and hydrology of tropical South
America inferred from an isotopic and chemical model of Lake
Titicaca, Bolivia and Peru},
Journal = {Quaternary Research},
Volume = {56},
Number = {1},
Pages = {1-9},
Publisher = {Cambridge University Press (CUP)},
Year = {2001},
Month = {January},
ISSN = {0033-5894},
url = {http://dx.doi.org/10.1006/qres.2001.2244},
Abstract = {A simple mass balance model provides insight into the
hydrologic, isotopic, and chemical responses of Lake
Titicaca to past climatic changes. Latest Pleistocene
climate of the Altiplano is assumed to have been 20% wetter
and 5°C colder than today, based on previous modeling. Our
simulation of lacustrine change since 15,000 cal yr B.P. is
forced by these modeled climate changes. The latest
Pleistocene Lake Titicaca was deep, fresh, and overflowing.
The latest Pleistocene riverine discharge from the lake was
about 8 times greater than the modern average, sufficient to
allow the expansion of the great paleolake Tauca on the
central Altiplano. The lake δ18O value averaged about -
13‰ SMOW (the modern value is about -4.2‰). The early
Holocene decrease in precipitation caused Lake Titicaca to
fall below its outlet and contributed to a rapid desiccation
of paleolake Tauca. Continued evaporation caused the 100-m
drop in lake level, but only a slight (1-2‰) increase
(relative to modern) in δ18O of early Holocene lake waters.
This Holocene lowstand level of nearly 100 m was most likely
produced by a precipitation decrease, relative to modern, of
about 40%. The lake was saline as recently as 2000 cal yr
B.P. The timing of these hydrologic changes is in general
agreement with calculated changes of insolation forcing of
the South American summer monsoon. © 2001 University of
Washington.},
Doi = {10.1006/qres.2001.2244},
Key = {fds278685}
}
@article{fds278698,
Author = {Rowe, HD and Guilderson, TP and Dunbar, RB and Southon, JR and Seltzer,
GO and Mucciarone, DA and Fritz, SC and Baker, PA},
Title = {Late Quaternary lake-level changes constrained by
radiocarbon and stable isotope studies on sediment cores
from Lake Titicaca, South America},
Journal = {Global and Planetary Change},
Volume = {38},
Number = {3-4},
Pages = {273-290},
Publisher = {Elsevier BV},
Year = {2003},
Month = {January},
ISSN = {0921-8181},
url = {http://dx.doi.org/10.1016/S0921-8181(03)00031-6},
Abstract = {We present and compare AMS-14C geochronologies for sediment
cores recovered from Lake Titicaca, South America.
Radiocarbon dates from three core sites constrain the timing
of late Quaternary paleoenvironmental changes in the Central
Andes and highlight the site-specific factors that limit the
radiocarbon geochronometer. With the exception of
mid-Holocene sediments, all cores are generally devoid of
macrophyte fragments, thus bulk organic fractions are used
to build core chronologies. Comparisons of radiocarbon
results for chemically defined fractions (bulk decalcified,
humate, humin) suggest that ages derived from all fractions
are generally coherent in the post-13,500 yr BP time
interval. In the pre-13,500 yr BP time interval, ages
derived from humate extracts are significantly younger
(300-7000 years) than ages from paired humin residues. Gross
age incoherencies between paired humate and humin
sub-fractions in pre-13,500 yr BP sediments from all core
sites probably reflect the net downward migration of
humates. Ages derived from bulk decalcified fractions at our
shallow water (90 m) and deep water (230 m) core sites
consistently fall between ages derived from humate and humin
sub-fractions in the pre-13,500 yr BP interval, reflecting
that the bulk decalcified fraction is predominantly a
mixture of humate and humin sub-fractions. Bulk decalcified
ages from the pre-13,500 yr BP interval at our intermediate
depth core site (150 m) are consistently older than humate
(youngest) and humin sub-fractions. This uniform,
reproducible pattern can be explained by the mobilization of
a relatively older organic sub-fraction during and after the
re-acidification step following the alkaline treatment of
the bulk sediment. The inferred existence of this
'alkali-mobile, acid-soluble' sub-fraction implies a
different depositional/post-depositional history that is
potentially associated with a difference in source material.
While internally consistent geochronologies can be developed
for the Lake Titicaca sequence using different organic
fractions, mobile organic sub-fractions and fractions
containing mobile sub-fractions should generally be avoided
in geochronology studies. Consequently, we believe humin
and/or bulk decalcified ages provide the most consistent
chronologies for the post-13,500 yr BP interval, and humin
ages provide the most representative ages for sedimentation
prior to 13,500 yr BP interval. Using the age model derived
from the deep water core site and a previously published
isotope-based lake-level reconstruction, we present a
qualitative record of lake level in the context of several
ice-core records from the western hemisphere. We find the
latest Pleistocene lake-level response to changing
insolation began during or just prior to the
Bølling/Allerød period. Using the isotope-based lake-level
reconstruction, we also find the 85-m drop in lake level
that occurred during the mid-Holocene was synchronous with
an increase in the variability of ice-core δ18O from a
nearby icecap, but was not reflected in any of the polar
ice-core records recovered from the interior of Antarctica
and Greenland. © 2003 Published by Elsevier
B.V.},
Doi = {10.1016/S0921-8181(03)00031-6},
Key = {fds278698}
}
@article{fds278702,
Author = {Rigsby, CA and Bradbury, JP and Baker, PA and Rollins, SM and Warren,
MR},
Title = {Late Quaternary palaeolakes, rivers, and wetlands on the
Bolivian Altiplano and their palaeoclimatic
implications},
Journal = {Journal of Quaternary Science},
Volume = {20},
Number = {7-8},
Pages = {671-691},
Publisher = {WILEY},
Year = {2005},
Month = {October},
ISSN = {0267-8179},
url = {http://dx.doi.org/10.1002/jqs.986},
Abstract = {Drill cores of sediments from the Rio Desaguadero valley,
Bolivia, provide new information about the climate of
tropical South America over the past 50 000 years. The
modern Rio Desaguadero is fed by Lake Titicaca overflow (and
by local tributaries) in the wetter northern Altiplano and
discharges into Lake Poopo in the more arid central
Altiplano. During the late Quaternary the Rio Desaguadero
valley was the site of several generations of palaeolakes
and wetlands that formed during periods of increased
precipitation and local runoff, augmented by increased
overflow from Lake Titicaca. Sediments recovered by drilling
in eight localities along the 390-km long valley of the Rio
Desaguadero yield a regional history of lacustrine
sedimentation and effective precipitation. Lacustrine strata
in the drill cores record 12 distinct wet periods in the
past 50 000 years. Four of these wet periods resulted in the
formation of major palaeolakes in the Rio Desaguadero
valley: during the last glacial maximum from before 20 000
to 16 000 cal. yr BP, during the late glacial from about 14
000 to 12 000 cal. yr BP, in the early Holocene from about
10 000 to 7900 cal. yr BP, and in the late Holocene from
4500 cal. yr BP to present. The period that appears to have
been most arid was between 7900 and 4500 cal. yr BP. The
Altiplano wet periods were generally synchronous with North
Atlantic cold events (respectively, the last glacial
maximum, the Younger Dryas, the 8200 cal. yr BP event, and
the Neoglacial) implying a relationship between past
precipitation variability in tropical South America and
North Atlantic sea-surface temperature. Copyright © 2005
John Wiley & Sons, Ltd.},
Doi = {10.1002/jqs.986},
Key = {fds278702}
}
@article{fds278726,
Author = {Rigsby, CA and Hemric, EM and Baker, PA},
Title = {Late Quaternary Paleohydrology of the Madre de Dios River,
southwestern Amazon Basin, Peru},
Journal = {Geomorphology},
Volume = {113},
Number = {3-4},
Pages = {158-172},
Publisher = {Elsevier BV},
Year = {2009},
Month = {December},
ISSN = {0169-555X},
url = {http://dx.doi.org/10.1016/j.geomorph.2008.11.017},
Abstract = {Late Quaternary climatic and hydrologic variability
triggered changes in fluvial deposition and erosion along
the course of the Madre de Dios River, Peru, the largest
tributary basin of the Madeira basin, itself the largest
tributary basin of the Amazon. Three laterally extensive,
Quaternary-age, terrace tracts are present within the Madre
de Dios basin. Analysis of sedimentary facies, present in
the modern cut banks and terraced sequences, along with
radiocarbon dates on fossil wood and leaf material preserved
in the terraced strata, allow reconstruction of the Late
Quaternary depositional history of the sedimentary
sequences, including determination of the approximate timing
of aggradation and downcutting episodes and its relationship
to the timing of past climate change in this portion of the
Amazon basin and beyond. The Quaternary sediments underlying
the terraces most often recorded deposition in a
coarse-grained meandering fluvial system. The T3 terrace,
the highest terrace, is underlain by the Miocene (?) Ipururi
Formation, which is unconformably overlain by the late
Miocene-Pleistocene (?) (> 48,000 cal yrs BP) Madre de Dios
Formation, a multistory coarse-sandy to gravelly channel and
point bar complex. The latter was downcut before 29,850 ±
100 cal yrs BP. This downcut landscape was infilled by
meandering fluvial strata characterized by gravelly channel
deposits in a sequence dominated by floodplain and lateral
accretion deposits. These strata were in turn downcut to
form the T2 terrace before 11,970 ± 100 cal yrs BP. A
third episode of aggradation resulted in the deposition of a
sand-dominated meandering channel complex that infilled the
T2 valley and was subsequently downcut after 3780 ± 50 cal
yrs BP. This most recent terrace is infilled by the modern
fluvial sediment, which has been actively aggrading since at
least 870 ± 50 cal yrs BP. Importantly, the Madre de Dios
fluvial system actively aggraded between 30,000 and
25,000 cal yrs BP, (and likely much younger, as dated
samples were, thus far, only found near the base of the T2
sequence). This observation implies that some combination of
(1) increased precipitation and decreased temperature, (2)
decreased evapotranspiration and increased runoff, (3)
increased Andean glacial erosion and increased sediment
supply, and (4) decreased atmospheric CO2 (hence decreased
rain-forest primary productivity and altered rain-forest
physiology/ecology), entering the last glacial maximum
period brought about increased floodplain deposition in the
southwestern Amazon. Elsewhere in the Amazon basin few, if
any, fluvial sediments of this age range have been observed.
The start of the next major phase of aggradation coincided
with the Younger Dryas and suggested that floodplain
sedimentation in the lowlands was again related to cold and
wet conditions in the adjacent highlands (and perhaps in the
lowlands as well) and that Madre de Dios history was also
tied to large-scale global climate. This aggradation may
have continued throughout the early and mid-Holocene, until
at least 3,780 cal yr BP. If so (and this is uncertain),
this episode of sedimentation took place during a dry
period. © 2009 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.geomorph.2008.11.017},
Key = {fds278726}
}
@article{fds278690,
Author = {D'Agostino, K and Seltzer, G and Baker, P and Fritz, S and Dunbar,
R},
Title = {Late-Quaternary lowstands of Lake Titicaca: Evidence from
high-resolution seismic data},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {179},
Number = {1-2},
Pages = {97-111},
Publisher = {Elsevier BV},
Year = {2002},
Month = {April},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/S0031-0182(01)00411-4},
Abstract = {Approximately 600 km of high-resolution seismic reflection
data were collected to investigate the late-Quaternary
stratigraphic development of Lake Titicaca. The focus of
this report is on two seismic sequence boundaries, which are
interpreted as erosional surfaces formed at times of low
lake level. The younger erosional surface occurs as much as
90 m below the present lake level and up to 8 m below the
present sediment-water interface. This erosional surface is
interpreted to be coeval with a well-documented early- to
mid-Holocene lowstand, dated between ∼ 8000 and 3600 cal
yr BP. An earlier and previously unknown erosional surface
occurs at a sub-bottom depth of approximately 30 m, and as
much as 240 m below the present lake level, which implies a
major late-Pleistocene lowstand of Lake Titicaca. By
extrapolation of sedimentation rates from the upper ∼ 14 m
of sediment, we estimate the age of this older lowstand at >
90000 cal yr BP. Both lowstands of Lake Titicaca indicated
by the seismic data are likely to have been a response to
climatic change in the region. © 2002 Elsevier Science B.V.
All rights reserved.},
Doi = {10.1016/S0031-0182(01)00411-4},
Key = {fds278690}
}
@article{fds278714,
Author = {Ballantyne, AP and Lavine, M and Crowley, TJ and Liu, J and Baker,
PB},
Title = {Meta-analysis of tropical surface temperatures during the
Last Glacial Maximum},
Journal = {Geophysical Research Letters},
Volume = {32},
Number = {5},
Pages = {1-4},
Publisher = {American Geophysical Union (AGU)},
Year = {2005},
Month = {March},
url = {http://dx.doi.org/10.1029/2004GL021217},
Abstract = {The magnitude of tropical cooling during the Last Glacial
Maximum (LGM) has been the subject of uncertainty for over
25 years. We use principles of meta-analysis as an objective
approach to reconcile estimates from different proxies. This
approach treats each observation as a random estimate of the
true mean and weights estimates by their reported precision.
We assigned global uncertainties to proxies and derived a
new regional standard deviation for temperatures calculated
from the Sr/Ca ratio in tropical corals (σ = 1.4°C). Using
a Bayesian spatial interpolation scheme, we estimate a mean
cooling of LGM tropical sea surface temperatures of -2.7 ±
0.5°C (±σ) and surface air temperatures of -5.4 ± 0.3°C
(±σ). Copyright 2005 by the American Geophysical
Union.},
Doi = {10.1029/2004GL021217},
Key = {fds278714}
}
@article{fds278701,
Author = {Cronin, TM and Dowsett, HJ and Dwyer, GS and Baker, PA and Chandler,
MA},
Title = {Mid-Pliocene deep-sea bottom-water temperatures based on
ostracode Mg/Ca ratios},
Journal = {Marine Micropaleontology},
Volume = {54},
Number = {3-4},
Pages = {249-261},
Publisher = {Elsevier BV},
Year = {2005},
Month = {January},
ISSN = {0377-8398},
url = {http://hdl.handle.net/10161/7000 Duke open
access},
Abstract = {We studied magnesium:calcium (Mg/Ca) ratios in shells of the
deep-sea ostracode genus Krithe from a short interval in the
middle Pliocene between 3.29 and 2.97 Ma using deep-sea
drilling sites in the North and South Atlantic in order to
estimate bottom water temperatures (BWT) during a period of
climatic warmth. Results from DSDP and ODP Sites 552A, 610A,
607, 658A, 659A, 661A and 704 for the period Ma reveal both
depth and latitudinal gradients of mean Mg/Ca values.
Shallower sites (552A, 610A and 607) have higher mean Mg/Ca
ratios (10.3, 9.7, 10.1 mmol/mol) than deeper sites (661A,
6.3 mmol/mol), and high latitude North Atlantic sites (552A,
610A, 607) have higher Mg/Ca ratios than low latitude (658A:
9.8 mmol/mol, 659A: 7.7 mmol/mol, 661A: 6.3 mmol/mol) and
Southern Ocean (704: 8.0 mmol/mol) sites. Converting Mg/Ca
ratios into estimated temperatures using the calibration of
Dwyer et al. (1995) [Dwyer, G.S., Cronin, T.M., Baker, P.A.,
Raymo, M.E., Buzas, J.S., Corrège, T., 1995. North Atlantic
deepwater temperature change during late Pliocene and late
Quaternary climatic cycles. Science 270, 1347-1351] suggests
that mean middle Pliocene bottom water temperatures at the
study sites in the deep Atlantic were about the same as
modern temperatures. However, brief pulses of elevated BWT
occurred several times between 3.29 and 2.97 Ma in both the
North and South Atlantic Ocean suggesting short-term changes
in deep ocean circulation.},
Doi = {10.1016/j.marmicro.2004.12.003},
Key = {fds278701}
}
@article{fds278723,
Author = {Fritz, SC and Baker, PA and Ekdahl, E and Seltzer, GO and Stevens,
LR},
Title = {Millennial-scale climate variability during the Last Glacial
period in the tropical Andes},
Journal = {Quaternary Science Reviews},
Volume = {29},
Number = {7-8},
Pages = {1017-1024},
Publisher = {Elsevier BV},
Year = {2010},
Month = {April},
ISSN = {0277-3791},
url = {http://dx.doi.org/10.1016/j.quascirev.2010.01.001},
Abstract = {Millennial-scale climate variation during the Last Glacial
period is evident in many locations worldwide, but it is
unclear if such variation occurred in the interior of
tropical South America, and, if so, how the low-latitude
variation was related to its high-latitude counterpart. A
high-resolution record, derived from the deep drilling of
sediments on the floor of Lake Titicaca in the southern
tropical Andes, is presented that shows clear evidence of
millennial-scale climate variation between ∼60 and 20 ka
BP. This variation is manifested by alternations of two
interbedded sedimentary units. The two units have
distinctive sedimentary, geochemical, and paleobiotic
properties that are controlled by the relative abundance of
terrigenous or nearshore components versus pelagic
components. The sediments of more terrigenous or nearshore
nature likely were deposited during regionally wetter
climates when river transport of water and sediment was
higher, whereas the sediments of more pelagic character were
deposited during somewhat drier climates regionally. The
majority of the wet periods inferred from the Lake Titicaca
sediment record are correlated with the cold events in the
Greenland ice cores and North Atlantic sediment cores,
indicating that increased intensity of the South American
summer monsoon was part of near-global scale climate
excursions. © 2010 Elsevier Ltd. All rights
reserved.},
Doi = {10.1016/j.quascirev.2010.01.001},
Key = {fds278723}
}
@article{fds278660,
Author = {Baker, PA and Malone, MJ and Burns, SJ and Swart,
PK},
Title = {Minor element and stable isotopic composition of the
carbonate fine fraction: Site 709, Indian
Ocean},
Journal = {Proc., Scientific Results, Odp, Leg 115, Mascarene
Plateau},
Pages = {661-675},
Year = {1990},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.115.178.1990},
Abstract = {Iron and manganese concentrations, and, to a lesser extent,
magnesium and strontium concentrations and carbon isotopic
ratios are affected by early diagenetic reactions. These
reactions are best observed in a slumped interval of
sediments that occurs between 13.0 and 17.5 Ma. As a result
of microbial reduction of manganese and iron oxides and
dissolved sulfate, it is hypothesized that small amounts of
mixed-metal carbonate cements are precipitated. These have
low carbon isotopic ratios and high concentrations of
metals. -from Authors},
Doi = {10.2973/odp.proc.sr.115.178.1990},
Key = {fds278660}
}
@article{fds345701,
Author = {Häggi, C and Schefuß, E and Sawakuchi, AO and Chiessi, CM and Mulitza,
S and Bertassoli, DJ and Hefter, J and Zabel, M and Baker, PA and Schouten,
S},
Title = {Modern and late Pleistocene particulate organic carbon
transport by the Amazon River: Insights from long-chain
alkyl diols},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {262},
Pages = {1-19},
Year = {2019},
Month = {October},
url = {http://dx.doi.org/10.1016/j.gca.2019.07.018},
Abstract = {The relative abundance of the C32 1,15 long-chain alkyl diol
(LCD) is an emerging proxy for the input of riverine aquatic
particulate organic carbon (POC) into coastal oceans. This
compound has the potential to complement other established
proxies reflecting riverine terrestrial POC input and allows
for a more nuanced assessment of riverine POC export to
coastal seas. The current understanding of this proxy is,
however, limited. In this study, we compare different
indices for riverine sediment input to coastal marine waters
(i.e. C32 1,15-LCD, BIT index and Fe/Ca ratio) in a
source-to-sink assessment in the Amazon River drainage
system and the northeast South American continental margin,
and we test their down-core applicability in a marine
gravity core containing late Pleistocene fluvial Amazonian
sediments. We show that the relative abundance of the C32
1,15-LCD is highest in water bodies with low flow velocity
and low turbidity such as the downstream portion of lowland
tributaries and floodplain lakes. Relative C32 1,15-LCD
abundance is lowest in Andean white water tributaries where
autotrophic productivity is hindered by high turbidity and
high flow velocity. We also find that suspended particulate
matter from all major tributaries during the extreme 2015
dry season has a similar LCD distribution to that of
floodplain lakes. This indicates that the chemical
composition of the tributaries is less relevant for the LCD
distribution than their physical properties such as flow
velocity and turbidity. Results from marine surface
sediments offshore the Amazon River estuary show significant
positive correlations between all three studied proxies. In
contrast, we find that the relative C32 1,15-LCD abundance
in the down-core record is anti-correlated to the BIT index
and Fe/Ca ratio. While BIT index and Fe/Ca ratio show high
(low) values during Heinrich stadials (Dansgaard-Oeschger
interstadials), the C32 1,15-LCD proxy shows the opposite
signal. BIT values are also higher during Marine Isotope
Stage (MIS) 2 than during MIS 3, in contrast to trends in
the C32 1,15-LCD proxy. We posit that this pattern arises
from a reduction in relative C32 1,15-LCD abundance and
total LCD productivity in the Amazon River during MIS 2 when
less-humid conditions and lower sea level led to reduced
area of floodplains. During Heinrich stadials, Andean
sediment input increased and led to higher turbidity that
resulted in lower C32 1,15-LCD production. Our study shows
that major changes in water discharge, sediment transport
and river morphology can lead to discrepancies between the
BIT index and the relative abundance of the C32 1,15-LCD.
Thus, we suggest that Amazonian aquatic and terrestrial POC
pools had contrasting responses to changes related to both
climate (e.g. increased Andean precipitation) and river
morphology (e.g. steeper along-channel slope due to falling
and low stand sea level).},
Doi = {10.1016/j.gca.2019.07.018},
Key = {fds345701}
}
@article{fds278631,
Author = {Baker, PA and Fritz, SC},
Title = {Nature and causes of Quaternary climate variation of
tropical South America},
Journal = {Quaternary Science Reviews},
Volume = {124},
Pages = {31-47},
Publisher = {Elsevier BV},
Year = {2015},
Month = {September},
ISSN = {0277-3791},
url = {http://dx.doi.org/10.1016/j.quascirev.2015.06.011},
Abstract = {This selective review of the Quaternary paleoclimate of the
South American summer monsoon (SASM) domain presents
viewpoints regarding a range of key issues in the field,
many of which are unresolved and some of which are
controversial. (1) El Niño-Southern Oscillation
variability, while the most important global-scale mode of
interannual climate variation, is insufficient to explain
most of the variation of tropical South American climate
observed in both the instrumental and the paleoclimate
records. (2) Significant climate variation in tropical South
America occurs on seasonal to orbital (i.e.
multi-millennial) time scales as a result of sea-surface
temperature (SST) variation and ocean-atmosphere
interactions of the tropical Atlantic. (3) Decadal-scale
climate variability, linked with this tropical Atlantic
variability, has been a persistent characteristic of climate
in tropical South America for at least the past half
millennium, and likely, far beyond. (4) Centennial-to-millennial
climate events in tropical South America were of longer
duration and, perhaps, larger amplitude than any observed in
the instrumental period, which is little more than a century
long in tropical South America. These were superimposed upon
both precession-paced insolation changes that caused
significant variation in SASM precipitation and
eccentricity-paced global glacial boundary conditions that
caused significant changes in the tropical South American
moisture balance. As a result, river sediment and water
discharge increased and decreased across tropical South
America, lake levels rose and fell, paleolakes arose and
disappeared on the Altiplano, glaciers waxed and waned in
the tropical Andes, and the tropical rainforest underwent
significant changes in composition and extent.To further
evaluate climate forcing over the last glacial cycle
(~125ka), we developed a climate forcing model that combines
summer insolation forcing and a proxy for North Atlantic SST
forcing to reconstruct long-term precipitation variation in
the SASM domain. The success of this model reinforces our
confidence in assigning causation to observed
reconstructions of precipitation. In addition, we propose a
critical correction for speleothem stable oxygen isotopic
ratios, which are among the most significant of paleoclimate
proxies in tropical South America for reconstruction of
variation of paleo-precipitation (or SASM intensity).
However, it is already well known that any particular
δ<sup>18</sup>O value observed in speleothem carbonate is
affected by two processes that have nothing to do with
changes in precipitation amount-the influence of temperature
on carbonate-water isotopic fractionation in the cave and
the influence of changing δ<sup>18</sup>O of seawater.
Quantitatively accounting for both "artifacts" can
significantly alter the interpretations of speleothem
records. In tropical South America, both adjustments act in
the same direction and have the tendency to increase the
true amplitude of the paleo-hydrologic signal (but by
different amounts in glacial and inter-glacial stages).
These corrections have even graver implications for the
interpretation of tropical Northern Hemisphere speleothem
records (e.g. Chinese speleothems) where the combined
adjustments tend to decrease or even eliminate the "true"
signal amplitude.},
Doi = {10.1016/j.quascirev.2015.06.011},
Key = {fds278631}
}
@article{fds359528,
Author = {Häggi, C and Hopmans, EC and Schefuß, E and Sawakuchi, AO and Schreuder, LT and Bertassoli, DJ and Chiessi, CM and Mulitza, S and Sawakuchi, HO and Baker, PA and Schouten, S},
Title = {Negligible Quantities of Particulate Low-Temperature
Pyrogenic Carbon Reach the Atlantic Ocean via the Amazon
River.},
Journal = {Global Biogeochemical Cycles},
Volume = {35},
Number = {9},
Pages = {e2021GB006990},
Year = {2021},
Month = {September},
url = {http://dx.doi.org/10.1029/2021gb006990},
Abstract = {Particulate pyrogenic carbon (PyC) transported by rivers and
aerosols, and deposited in marine sediments, is an important
part of the carbon cycle. The chemical composition of PyC is
temperature dependent and levoglucosan is a source-specific
burning marker used to trace low-temperature PyC.
Levoglucosan associated to particulate material has been
shown to be preserved during riverine transport and marine
deposition in high- and mid-latitudes, but it is yet unknown
if this is also the case for (sub)tropical areas, where 90%
of global PyC is produced. Here, we investigate transport
and deposition of levoglucosan in suspended and riverbed
sediments from the Amazon River system and adjacent marine
deposition areas. We show that the Amazon River exports
negligible amounts of levoglucosan and that concentrations
in sediments from the main Amazon tributaries are not
related to long-term mean catchment-wide fire activity.
Levoglucosan concentrations in marine sediments offshore the
Amazon Estuary are positively correlated to total organic
content regardless of terrestrial or marine origin,
supporting the notion that association of suspended or
dissolved PyC to biogenic particles is critical in the
preservation of PyC. We estimate that 0.5-10 × 10<sup>6</sup> g yr<sup>-1</sup>
of levoglucosan is exported by the Amazon River. This
represents only 0.5-10 ppm of the total exported PyC and
thereby an insignificant fraction, indicating that riverine
derived levoglucosan and low-temperature PyC in the tropics
are almost completely degraded before deposition. Hence, we
suggest caution in using levoglucosan as tracer for past
fire activity in tropical settings near rivers.},
Doi = {10.1029/2021gb006990},
Key = {fds359528}
}
@article{fds278674,
Author = {Dwyer, GS and Cronin, TM and Baker, PA and Raymo, ME and Buzas, JS and Corrège, T},
Title = {North atlantic deepwater temperature change during late
pliocene and late quaternary climatic cycles},
Journal = {Science (New York, N.Y.)},
Volume = {270},
Number = {5240},
Pages = {1347-1351},
Publisher = {American Association for the Advancement of Science
(AAAS)},
Year = {1995},
Month = {January},
url = {http://hdl.handle.net/10161/6997 Duke open
access},
Abstract = {Variations in the ratio of magnesium to calcium (Mg/Ca) in
fossil ostracodes from Deep Sea Drilling Project Site 607 in
the deep North Atlantic show that the change in bottom water
temperature during late Pliocene 41,000-year obliquity
cycles averaged 1.5°C between 3.2 and 2.8 million years ago
(Ma) and increased to 2.3°C between 2.8 and 2.3 Ma,
coincidentally with the intensification of Northern
Hemisphere glaciation. During the last two 100,000-year
glacial-to-interglacial climatic cycles of the Quaternary,
bottom water temperatures changed by 4.5°C. These results
show that glacial deepwater cooling has intensified since
3.2 Ma, most likely as the result of progressively
diminished deep-water production in the North Atlantic and
of the greater influence of Antarctic bottom water in the
North Atlantic during glacial periods. The ostracode Mg/Ca
data also allow the direct determination of the temperature
component of the benthic foraminiferal oxygen isotope record
from Site 607, as well as derivation of a hypothetical
sea-level curve for the late Pliocene and late Quaternary.
The effects of dissolution on the Mg/Ca ratios of ostracode
shells appear to have been minimal.},
Doi = {10.1126/science.270.5240.1347},
Key = {fds278674}
}
@article{fds278651,
Author = {Baker, PA and Burns, SJ},
Title = {Occurrence and formation of dolomite in organic-rich
continental margin sediments.},
Journal = {Bulletin, American Association of Petroleum
Geologists},
Volume = {69},
Number = {11},
Pages = {1917-1930},
Year = {1985},
Month = {January},
Abstract = {Dolomite forms in sediments over large areas of the
ocean-floor. The most common environment is organic-rich
calcareous continental margin sediments.-K.A.R.},
Key = {fds278651}
}
@article{fds278662,
Author = {Baker, P and Allen, M},
Title = {Occurrence of dolomite in Neogene phosphatic
sediments},
Journal = {Phosphate Deposits of the World, Vol. 3. Neogene to Modern
Phosphorites},
Pages = {73-86},
Year = {1990},
Month = {January},
Abstract = {Dolomite precipitation in phosphatic sediments may take
place within the zone of sulfate reduction or in the deeper
zone of methanogenesis. High abundances of dolomite in a
sediment require that most of this dolomite formed at
shallow burial depths. Phosphate precipitation occurs
shallower and faster than dolomite precipitation. Most of
the apatite in a phosphorite deposit precipitates within a
few centimeters of the sediment-water interface in the
uppermost zone of sulfate reduction. -from
Authors},
Key = {fds278662}
}
@article{fds278682,
Author = {Cronin, TM and Dwyer, GS and Baker, PA and Rodriguez-Lazaro, J and DeMartino, DM},
Title = {Orbital and suborbital variability in North Atlantic bottom
water temperature obtained from deep-sea ostracod Mg/Ca
ratios},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {162},
Number = {1-2},
Pages = {45-57},
Publisher = {Elsevier BV},
Year = {2000},
Month = {September},
ISSN = {0031-0182},
url = {http://hdl.handle.net/10161/6479 Duke open
access},
Abstract = {Magnesium/calcium (Mg/Ca) ratios were measured in the
deep-sea ostracod (Crustacea) genus Krithe from Chain core
82-24-4PC from the western mid-Atlantic Ridge (3427 m) in
order to estimate ocean circulation and bottom water
temperature (BWT) variability over the past 200,000 years.
Mg/Ca ratios have been used as a paleothermometer because
the ratios are controlled primarily by ambient water
temperatures at the time the organism secretes its adult
carapace. Over the past two glacial-interglacial cycles,
Mg/Ca values oscillated between about 7 mmol/mol and 12
mmol/mol, equivalent to a BWT range of 0 to > 3.5°C. The
lowest values were obtained on specimens from glacial marine
isotope stages (MISs) 2, 4 and 6; the highest values were
obtained from specimens from the early part of the Holocene
interglacial (MIS 1), and also from MISs 5 and 7. These
trends suggest that BWTs in the North Atlantic Ocean
fluctuate over orbital time scales. Suborbital variability
in Mg/Ca ratios and BWT was also observed for the past
100,000 years. Ratios rose from ~8 mmol/mol to ~10 mmol/mol
(implying a BWT increase of ~1 to 3°C) during 14 Mg/Ca
excursions. The highest ratios were found in Krithe dated at
approximately 32, 36-38, 43, 48, 73, 85 and 93 ka. Although
the age model for the Chain 82-24-4PC and temporal
resolution do not allow precise correlation, some of these
deep-sea bottom temperature excursions appear to correspond
to Heinrich events recorded in other regions of the North
Atlantic and perhaps Dansgaard-Oeschger interstadial events
recorded in Greenland ice cores. If confirmed, this would
support the hypothesis that millennial-scale oscillations of
climate in the North Atlantic are capable of affecting
global climate via thermohaline circulation changes. (C)
2000 Elsevier Science B.V.},
Doi = {10.1016/S0031-0182(00)00104-8},
Key = {fds278682}
}
@article{fds328723,
Author = {Sun, S and Schefuß, E and Mulitza, S and Chiessi, CM and Sawakuchi, AO and Zabel, M and Baker, PA and Hefter, J and Mollenhauer,
G},
Title = {Origin and processing of terrestrial organic carbon in the
Amazon system: Lignin phenols in river, shelf, and fan
sediments},
Journal = {Biogeosciences},
Volume = {14},
Number = {9},
Pages = {2495-2512},
Publisher = {Copernicus GmbH},
Year = {2017},
Month = {May},
url = {http://dx.doi.org/10.5194/bg-14-2495-2017},
Abstract = {The Amazon River transports large amounts of terrestrial
organic carbon (OCterr) from the Andean and Amazon
neotropical forests to the Atlantic Ocean. In order to
compare the biogeochemical characteristics of OCterr in the
fluvial sediments from the Amazon drainage basin and in the
adjacent marine sediments, we analysed riverbed sediments
from the Amazon mainstream and its main tributaries as well
as marine surface sediments from the Amazon shelf and fan
for total organic carbon (TOC) content, organic carbon
isotopic composition (δ13CTOC), and lignin phenol
compositions. TOC and lignin content exhibit positive
correlations with Al/Si ratios (indicative of the sediment
grain size) implying that the grain size of sediment
discharged by the Amazon River plays an important role in
the preservation of TOC and leads to preferential
preservation of lignin phenols in fine particles. Depleted
δ13CTOC values (-26.1 to -29.9%) in the main tributaries
consistently correspond with the dominance of C3 vegetation.
Ratios of syringyl to vanillyl (S/V) and cinnamyl to
vanillyl (C/V) lignin phenols suggest that non-woody
angiosperm tissues are the dominant source of lignin in the
Amazon basin. Although the Amazon basin hosts a rich
diversity of vascular plant types, distinct regional lignin
compositions are not observed. In the marine sediments, the
distribution of δ13CTOC and Λ8 (sum of eight lignin
phenols in organic carbon (OC), expressed as mg/100ĝ€mg
OC) values implies that OCterr discharged by the Amazon
River is transported north-westward by the North Brazil
Current and mostly deposited on the inner shelf. The lignin
compositions in offshore sediments under the influence of
the Amazon plume are consistent with the riverbed samples
suggesting that processing of OCterr during offshore
transport does not change the encoded source information.
Therefore, the lignin compositions preserved in these
offshore sediments can reliably reflect the vegetation in
the Amazon River catchment. In sediments from the Amazon
fan, low lignin content, relatively depleted δ13CTOC values
and high (Ad/Al)V ratios indicating highly degraded lignin
imply that a significant fraction of the deposited OCterr is
derived from petrogenic (sourced from ancient rocks)
sources.},
Doi = {10.5194/bg-14-2495-2017},
Key = {fds328723}
}
@article{fds328724,
Author = {Häggi, C and Sawakuchi, AO and Chiessi, CM and Mulitza, S and Mollenhauer, G and Sawakuchi, HO and Baker, PA and Zabel, M and Schefuß, E},
Title = {Origin, transport and deposition of leaf-wax biomarkers in
the Amazon Basin and the adjacent Atlantic},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {192},
Pages = {149-165},
Publisher = {Elsevier BV},
Year = {2016},
Month = {November},
url = {http://dx.doi.org/10.1016/j.gca.2016.07.002},
Abstract = {Paleoenvironmental studies based on terrigenous biomarker
proxies from sediment cores collected close to the mouth of
large river systems rely on a proper understanding of the
processes controlling origin, transport and deposition of
biomarkers. Here, we contribute to the understanding of
these processes by analyzing long-chain n-alkanes from the
Amazon River system. We use the δD composition of
long-chain n-alkanes from river bed sediments from the
Amazon River and its major tributaries, as well as marine
core-top samples collected off northeastern South America as
tracers for different source areas. The δ13C composition of
the same compounds is used to differentiate between
long-chain n-alkanes from modern forest vegetation and
petrogenic organic matter. Our δ13C results show depleted
δ13C values (−33 to −36‰) in most samples, indicating
a modern forest source for most of the samples. Enriched
values (−31 to −33‰) are only found in a few samples
poor in organic carbon indicating minor contributions from a
fossil petrogenic source. Long-chain n-alkane δD analyses
show more depleted values for the western tributaries, the
Madeira and Solimões Rivers (−152 to −168‰), while
n-alkanes from the lowland tributaries, the Negro, Xingu and
Tocantins Rivers (−142 to −154‰), yield more enriched
values. The n-alkane δD values thus reflect the mean annual
isotopic composition of precipitation, which is most
deuterium-depleted in the western Amazon Basin and more
enriched in the eastern sector of the basin. Samples from
the Amazon estuary show a mixed long-chain n-alkane δD
signal from both eastern lowland and western tributaries.
Marine core-top samples underlying the Amazon freshwater
plume yield δD values similar to those from the Amazon
estuary, while core-top samples from outside the plume
showed more enriched values. Although the variability in the
river bed data precludes quantitative assessment of relative
contributions, our results indicate that long-chain
n-alkanes from the Amazon estuary and plume represent an
integrated signal of different regions of the onshore basin.
Our results also imply that n-alkanes are not extensively
remineralized during transport and that the signal at the
Amazon estuary and plume includes refractory compounds
derived from the western sector of the Basin. These findings
will aid in the interpretation of plant wax-based records of
marine sediment cores collected from the adjacent
ocean.},
Doi = {10.1016/j.gca.2016.07.002},
Key = {fds328724}
}
@article{fds278652,
Author = {Kennett, JP and Von Der Borch and C and Baker, PA and Barton, CE and Boersma, A and Cauler, JP and Dudley, WC and Gardner, JV and Jenkins,
DG and Lohman, WH and Martini, E and Merrill, RB and Morin, R and Nelson,
CS and Robert, C and Srinivasan, MS and Stein, R and Takeuchi, A and Murphy, MG},
Title = {Palaeotectonic implications of increased late Eocene-early
Oligocene volcanism from South Pacific DSDP
sites},
Journal = {Nature},
Volume = {316},
Number = {6028},
Pages = {507-511},
Publisher = {Springer Nature},
Year = {1985},
Month = {December},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/316507a0},
Abstract = {Late Eocene-early Oligocene (42-35 Myr) sediments cored at
two DSDP sites in the south-west Pacific contain evidence of
a pronounced increase in local volcanic activity,
particularly in close association with the Eocene-Oligocene
boundary. This pulse of volcanism is coeval with that in New
Zealand and resulted from the development of an Indo-
Australian / Pacific Plate boundary through the region
during the late Eocene. The late Eocene / earliest Oligocene
was marked by widespread volcanism and tectonism throughout
the Pacific and elsewhere, and by one of the most important
episodes of Cenozoic climatic cooling. © 1985 Nature
Publishing Group.},
Doi = {10.1038/316507a0},
Key = {fds278652}
}
@article{fds346446,
Author = {Feitl, M and Kern, AK and Jones, A and Fritz, SC and Baker, PA and Joeckel,
RM and Salenbien, W and Willard, D},
Title = {Paleoclimate of the subtropical Andes during the latest
Miocene, Lauca Basin, Chile},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {534},
Year = {2019},
Month = {November},
url = {http://dx.doi.org/10.1016/j.palaeo.2019.109336},
Abstract = {Uplift of the Andean Cordillera during the Miocene and
Pliocene produced large-scale changes in regional
atmospheric circulation that impacted local ecosystems. The
Lauca Basin (northern Chilean Altiplano) contains variably
fluvial and lacustrine sedimentary sequences spanning the
interval from 8.7 to 2.3 Ma. Field samples were collected
from paleo-lacustrine sediments in the basin. Sediments were
dated using detrital zircon geochronology on volcanic tuffs,
yielding an age range between ~5.57 and 5.44 Ma. These new
age constraints provided an opportunity to evaluate changes
in the Lauca Basin ecosystem across this dynamic
Miocene-Pliocene transition. We employed multiple proxies
(lithofacies analysis, diatoms, pollen, and oxygen stable
isotopes of authigenic carbonates) to interpret ancient
lacustrine and terrestrial paleoenvironments. Alternations
among mudstone, carbonate, and evaporitic facies indicate
lake-level variability through time. The diatom assemblage
is characterized by meso- to hypersaline and
alkaline-tolerant taxa typical of shallow lakes. The δ18O
values ranged from −8.96 to −2.22‰ indicating
fluctuations in water balance. Pollen taxa in the outcrop
are typical of a transitional stage between seasonal cloud
forest and open grassland. Together, these proxies indicate
that the Lauca paleolake sediments were deposited under a
wetter-than-modern climate with high temporal variability.
Our results refine previous studies in the Lauca Basin and
are consistent with other regional studies suggesting that
the South American summer monsoon at the Miocene-Pliocene
transition was more intense than it is at
present.},
Doi = {10.1016/j.palaeo.2019.109336},
Key = {fds346446}
}
@article{fds278689,
Author = {Baker, PA},
Title = {Paleoclimate. Trans-Atlantic climate connections.},
Journal = {Science (New York, N.Y.)},
Volume = {296},
Number = {5565},
Pages = {67-68},
Year = {2002},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/11935013},
Doi = {10.1126/science.1071162},
Key = {fds278689}
}
@article{fds278727,
Author = {Leavitt, PR and Fritz, SC and Anderson, NJ and Baker, PA and Blenckner,
T and Bunting, L and Catalan, J and Conley, DJ and Hobbs, WO and Jeppesen,
E and Korhola, A and McGowan, S and Rühland, K and Rusak, JA and Simpson,
GL and Solovieva, N and Werneo, J},
Title = {Paleolimnological evidence of the effects on lakes of energy
and mass transfer from climate and humans},
Journal = {Limnology and Oceanography},
Volume = {54},
Number = {6 PART 2},
Pages = {2330-2348},
Publisher = {WILEY},
Year = {2009},
Month = {January},
ISSN = {0024-3590},
url = {http://dx.doi.org/10.4319/lo.2009.54.6_part_2.2330},
Abstract = {The premise of this article is that climate effects on lakes
can be quantified most effectively by the integration of
process-oriented limnological studies with paleolimnological
research, particularly when both disciplines operate within
a common conceptual framework. To this end, the energy
(E)-mass (m) flux framework (Em flux) is developed and
applied to selected retrospective studies to demonstrate
that climate variability regulates lake structure and
function over diverse temporal and spatial scales through
four main pathways: rapid direct transfer of E to the lake
surface by irradiance, heat, and wind; slow indirect effects
of E via changes in terrestrial development and subsequent m
subsidies to lakes; direct influx of m as precipitation,
particles, and solutes from the atmosphere; and indirect
influx of water, suspended particles, and dissolved
substances from the catchment. Sedimentary analyses are used
to illustrate the unique effects of each pathway on lakes
but suggest that interactions among mechanisms are complex
and depend on the landscape position of lakes, catchment
characteristics, the range of temporal variation of
individual pathways, ontogenetic changes in lake basins, and
the selective effects of humans on m transfers. In
particular, preliminary synthesis suggests that m influx can
overwhelm the direct effects of E transfer to lakes,
especially when anthropogenic activities alter m subsidies
from catchments. © 2009, by the American Society of
Limnology and Oceanography, Inc.},
Doi = {10.4319/lo.2009.54.6_part_2.2330},
Key = {fds278727}
}
@article{fds369104,
Author = {Luethje, M and Benito, X and Schneider, T and Mosquera, PV and Baker, P and Fritz, SC},
Title = {Paleolimnological responses of Ecuadorian páramo lakes to
local and regional stressors over the last two
millennia},
Journal = {Journal of Paleolimnology},
Volume = {69},
Number = {4},
Pages = {305-323},
Year = {2023},
Month = {April},
url = {http://dx.doi.org/10.1007/s10933-022-00274-5},
Abstract = {Increasing surface air temperatures and human influences
(e.g., agriculture, livestock grazing, tourism) are altering
lacustrine ecosystems in the South American Andean páramo,
and these influences are evident in changes in the
diatom-species composition in sediment cores from the region
that span the last ~ 150 years. Existing studies are
limited by their short temporal scales and limited spatial
extent. We analyzed two sediment cores spanning the last two
millennia from the northern (Laguna Piñan) and southern
(Laguna Fondococha) Andean páramo of Ecuador to provide a
longer-term perspective on lake dynamics. Both lakes show
shifts in the dominant diatoms through time. Fondococha
diatoms shifted in dominance between two Aulacoseira species
and in the planktic to benthic ratio, and these shifts are
interpreted as evidence of changing lake level. The inferred
shifts are corroborated by changes in sediment geochemistry.
Piñan shows a directional shift in the diatom assemblage
over the period of the record, from benthic diatoms tolerant
of high dissolved organic carbon (DOC), low pH, and low
nutrients, to an assemblage characteristic of lower DOC,
higher pH, nutrients and lake levels. Shifts in Piñan’s
diatoms are correlated with tephra layers in the sediment,
suggesting that local volcanic deposition may have been
responsible for altering the catchment and lake
geochemistry. This is supported by relatively high δ13C
values in organic matter associated with tephra layers,
which become more negative up-section. Our study suggests
that remote lakes in spatially heterogenous montane regions
act as sentinels of different facets of environmental change
and provide insights into Andean ecosystem responses to
environmental perturbations.},
Doi = {10.1007/s10933-022-00274-5},
Key = {fds369104}
}
@article{fds345472,
Author = {Kay, RF and Gonzales, LA and Salenbien, W and Martinez, J-N and Cooke,
SB and Valdivia, LA and Rigsby, C and Baker, PA},
Title = {Parvimico materdei gen. et sp. nov.: A new platyrrhine from
the Early Miocene of the Amazon Basin, Peru.},
Journal = {Journal of Human Evolution},
Volume = {134},
Pages = {102628},
Year = {2019},
Month = {September},
url = {http://dx.doi.org/10.1016/j.jhevol.2019.05.016},
Abstract = {Three field seasons of exploration along the Río Alto Madre
de Dios in Peruvian Amazonia have yielded a fauna of
micromammals from a new locality AMD-45, at ∼12.8°S. So
far we have identified the new primate described here as
well as small caviomorph rodents, cenolestoid marsupials,
interatheriid notoungulates, xenarthrans, fish, lizards and
invertebrates. The site is in the Bala Formation as exposed
where the river transects a syncline. U-Pb dates on detrital
zircons constrain the locality's age at between
17.1 ± 0.7 Ma and 18.9 ± 0.7 Ma, making the fauna
age-equivalent to that from the Pinturas Formation and the
older parts of the Santa Cruz Formation of Patagonian
Argentina (Santacrucian). The primate specimen is an unworn
M<sup>1</sup> of exceptionally small size (equivalent in
size to the extant callitrichine, Callithrix jacchus, among
the smallest living platyrrhines and the smallest
Eocene-Early Miocene platyrrhine yet recorded). Despite its
small size it is unlike extant callitrichines in having a
prominent cingulum hypocone. Based on the moderate
development of the buccal crests, this animal likely had a
diet similar to that of frugivorous callitrichines, and
distinctly different from the more similarly-sized
gummivores, Cebuella and C. jacchus. The phyletic position
of the new taxon is uncertain, especially given the
autapomorphic character of the tooth as a whole.
Nevertheless, its unusual morphology hints at a wholly
original and hitherto unknown Amazonian fauna, and
reinforces the impression of the geographic separation of
the Amazonian tropics from the more geographically isolated
southerly parts of the continent in Early Miocene
times.},
Doi = {10.1016/j.jhevol.2019.05.016},
Key = {fds345472}
}
@article{fds278704,
Author = {Ballantyne, AP and Rybczynski, N and Baker, PA and Harington, CR and White, D},
Title = {Pliocene Arctic temperature constraints from the growth
rings and isotopic composition of fossil
larch},
Journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
Volume = {242},
Number = {3-4},
Pages = {188-200},
Publisher = {Elsevier BV},
Year = {2006},
Month = {December},
ISSN = {0031-0182},
url = {http://dx.doi.org/10.1016/j.palaeo.2006.05.016},
Abstract = {Instrumental records reveal that the current rate of Arctic
warming greatly exceeds mean global warming. However, Arctic
temperatures during the Pliocene were considerably warmer
than present, making it an excellent time period for
investigating potential consequences of current warming
trends. Here we focus on an early Pliocene (4 to 5 Ma) peat
deposit from Ellesmere Island, characterized by a remarkable
fossil assemblage representative of a modern boreal forest.
Among the fossils are well-preserved samples of an extinct
larch (Larix groenlandii), which were exploited as an
archive of paleoclimatic information. We reconstruct
Pliocene terrestrial temperatures in the high Arctic using a
novel approach that combines measurements of ring-width and
oxygen isotopes. This technique was calibrated by analyzing
modern analog larch growing at the northern extent of their
range and accounting for biotic fractionation of oxygen
isotopes using a global database of modern trees. Based on
this approach, we estimated mean annual temperature in the
Arctic during the Pliocene to be - 5.5 ± 1.9 °C,
indicating that Arctic temperatures were 14.2 °C warmer
than today. This more precise multi-proxy estimate is
slightly warmer than previous estimates derived from
empirical evidence and general circulation models. Our
results also demonstrate that the biotic fractionation of
oxygen isotopes in cellulose is non-linear and dependent
upon regional factors affecting aridity, such as latitude
and elevation. Therefore the simultaneous measurement of
oxygen isotopes and morphological characteristics in
paleovegetation can be useful in constraining climatic
variables of Earth's past. © 2006 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.palaeo.2006.05.016},
Key = {fds278704}
}
@article{fds278653,
Author = {Baker, PA},
Title = {Pore-water chemistry of carbonate-rich sediments, Lord Howe
Rise, southwest Pacific Ocean.},
Journal = {Initial Reports Dsdp, Leg 90, Noumea, New Caledonia to
Wellington, New Zealand. Part 2},
Pages = {1249-1256},
Year = {1986},
Month = {January},
url = {http://dx.doi.org/10.2973/dsdp.proc.90.132.1986},
Abstract = {At all sites on Leg 90 on the carbonate-rich Lord Howe Rise,
Ca2+ concentrations increase and Mg2+ concentrations
decrease with increasing sub-bottom depth. The value of
ddCa2+/dMg2+ averages -0.45 mol/mol at these sites, an
unusually small negative value in comparison with sites on
basaltic crust. This supports the argument that the crust of
the Lord Howe Rise is siliceous. Carbonate recrystallization
is indicated by large increases in Sr2+ concentrations with
depth at all sites. The greater the degree of microbial
sulfate reduction, the higher is the pore water Sr2+
concentration. -from Author},
Doi = {10.2973/dsdp.proc.90.132.1986},
Key = {fds278653}
}
@article{fds278650,
Author = {Baker, PA and Kastner, M and Byerlee, JD and Lockner,
DA},
Title = {Pressure solution and hydrothermal recrystallization of
carbonate sediments - an experimental study -
reply},
Journal = {Marine Geology},
Volume = {51},
Number = {1-2},
Pages = {179-181},
Publisher = {Elsevier BV},
Year = {1983},
Month = {January},
ISSN = {0025-3227},
url = {http://dx.doi.org/10.1016/0025-3227(83)90097-X},
Doi = {10.1016/0025-3227(83)90097-X},
Key = {fds278650}
}
@article{fds278645,
Author = {Baker, PA and Kastner, M and Byerlee, JD and Lockner,
DA},
Title = {Pressure solution and hydrothermal recrystallization of
carbonate sediments — An experimental study},
Journal = {Marine Geology},
Volume = {38},
Number = {1-3},
Pages = {185-203},
Publisher = {Elsevier BV},
Year = {1980},
Month = {January},
url = {http://dx.doi.org/10.1016/0025-3227(80)90058-4},
Abstract = {The extent of calcite recrystallization was determined in
pressure-solution and hydrothermal experiments which were
conducted on deep-sea carbonates of low-Mg calcite, Iceland
spar, and reagent-grade calcite powder. In the
pressure-solution experiments, wet sediments were subjected
to confining pressures of 500–1500 bars and pore pressures
of 150–500 bars, at temperatures between 22° and 180°C,
for 21–240 h. The hydrothermal experiments were performed
in sealed teflon-coated bombs at 200°C, zero effective
stress, in sulfate-free sea water, for two weeks. The
hydrothermal system was solution-dominated. The extent of
calcite recrystallization was determined by measuring the
oxygen isotopic compositions of the pore fluids and solids
before and after each experiment. Scanning Electron
Microscope observations, porosity and specific surface-area
measurements were performed. In fine-grained carbonate
samples subjected to high effective stresses, the mechanism
for recrystallization apparently involves both relief of
strain energy at grain-to-grain contacts and decrease in
surface free energy by decreasing the surface area, while in
coarse-grained carbonates, relief of strain energy appears
to be the most important control of recrystallization. In
the hydrothermal experiments, however, decrease in surface
free energy is the only driving force for recrystallization.
Effective stress increased the rate of calcite
recrystallization. In both pressure-solution and
hydrothermal experiments, clay minerals retarded the
reaction. The effects of diatomite and basaltic glass on the
extent of calcite recrystallization was investigated only in
the hydrothermal experiments. Both admixed non-carbonate
materials retarded the reaction, diatomite being the most
effective inhibitor. Surface chemical reactions seem to be
responsible for the observed inhibitions of calcite
recrystallization. Increases in the extent of calcite
recrystallization with increasing ionic strength were
observed in hydrothermal experiments in NaCl solutions of
five different ionic strengths. © 1980, All rights
reserved.},
Doi = {10.1016/0025-3227(80)90058-4},
Key = {fds278645}
}
@article{fds336122,
Author = {Spanbauer, TL and Fritz, SC and Baker, PA},
Title = {Punctuated changes in the morphology of an endemic diatom
from Lake Titicaca},
Journal = {Paleobiology},
Volume = {44},
Number = {1},
Pages = {89-100},
Publisher = {Cambridge University Press (CUP)},
Year = {2018},
Month = {February},
url = {http://dx.doi.org/10.1017/pab.2017.27},
Abstract = {High levels of biodiversity and endemism in ancient lakes
have motivated research on evolutionary processes in these
systems. Drill-core records from Lake Titicaca (Bolivia,
Peru), an ancient lake in the high-elevation Altiplano,
record the history of climate, landscape dynamics, and
diatom evolution. That record was used to examine the
patterns and drivers of morphological evolution of an
endemic species complex of diatoms in the lake, the
Cyclostephanos andinus complex. In an attempt to delineate
species within the complex based on morphology, no
discernible evidence was found for species separation based
on an ordination analysis of multiple characters, but
multiple populations were detected based on the distribution
of valve size in individual samples. Likelihood modeling of
phyletic evolution showed that size evolved through
punctuated change. Correlation of size trends with
environmental variables indicates that C. andinus size
responded to regional environmental change driven by global
processes that influenced Lake Titicaca by affecting lake
level and thermal stratification.},
Doi = {10.1017/pab.2017.27},
Key = {fds336122}
}
@article{fds278706,
Author = {Fritz, SC and Baker, PA and Seltzer, GO and Ballantyne, A and Tapia, P and Cheng, H and Edwards, RL},
Title = {Quaternary glaciation and hydrologic variation in the South
American tropics as reconstructed from the Lake Titicaca
drilling project},
Journal = {Quaternary Research},
Volume = {68},
Number = {3},
Pages = {410-420},
Publisher = {Cambridge University Press (CUP)},
Year = {2007},
Month = {January},
ISSN = {0033-5894},
url = {http://dx.doi.org/10.1016/j.yqres.2007.07.008},
Abstract = {A 136-m-long drill core of sediments was recovered from
tropical high-altitude Lake Titicaca, Bolivia-Peru, enabling
a reconstruction of past climate that spans four cycles of
regional glacial advance and retreat and that is estimated
to extend continuously over the last 370,000 yr. Within the
errors of the age model, the periods of regional glacial
advance and retreat are concordant respectively with global
glacial and interglacial stages. Periods of ice advance in
the southern tropical Andes generally were periods of
positive water balance, as evidenced by deeper and fresher
conditions in Lake Titicaca. Conversely, reduced glaciation
occurred during periods of negative water balance and
shallow closed-basin conditions in the lake. The apparent
coincidence of positive water balance of Lake Titicaca and
glacial growth in the adjacent Andes with Northern
Hemisphere ice sheet expansion implies that regional water
balance and glacial mass balance are strongly influenced by
global-scale temperature changes, as well as by precessional
forcing of the South American summer monsoon. © 2007
University of Washington.},
Doi = {10.1016/j.yqres.2007.07.008},
Key = {fds278706}
}
@article{fds357858,
Author = {Guédron, S and Tolu, J and Delaere, C and Sabatier, P and Barre, J and Heredia, C and Brisset, E and Campillo, S and Bindler, R and Fritz, SC and Baker, PA and Amouroux, D},
Title = {Reconstructing two millennia of copper and silver metallurgy
in the Lake Titicaca region (Bolivia/Peru) using trace
metals and lead isotopic composition},
Journal = {Anthropocene},
Volume = {34},
Year = {2021},
Month = {June},
url = {http://dx.doi.org/10.1016/j.ancene.2021.100288},
Abstract = {Copper, silver, and gold exploitation has been a foundation
of economic and socio-cultural development of Andean
societies, at least for the last three millennia. The main
centers of pre-colonial metallurgy are well-known from
archeological artifacts, but temporal gaps inherent in this
record handicap a finer understanding of the modalities of
ore exploitation by succeeding civilizations. A continuous
record over time of trace metals emitted during ore smelting
operations make lake sediments excellent candidates to fill
those gaps. Two millennia of metallurgy were reconstructed
from atmospherically derived metals together with lead (Pb)
isotope ratios in two dated sediment cores from Lake
Titicaca. The first evidence for metallurgy is found during
the apogee of the Tiwanaku state (AD 800–1150), with a
higher copper (Cu) accumulation that can be attributed to
the smelting of local Cu ores, based on Pb isotopic
fingerprinting. During the Late Intermediate Period (AD
1150–1450), recorded peaks in metal deposition that
persisted for ∼ twenty years show that mining activities
were intensive but discontinuous. Pb isotope ratios suggest
diversified extractive activities, mainly located in the
southern part of the central Altiplano. Finally, the most
intense mining epoch began during the Inca Empire (ca. AD
1500) and lasted until the end of the Colonial Period (AD
1830), with unprecedented metal deposition over this
interval. Pb isotope fingerprinting shows that mining
operations occurred mainly in the Lake Titicaca and Potosi
areas and were responsible for metal emissions recorded in
the entire Altiplano, as evidenced by other
studies.},
Doi = {10.1016/j.ancene.2021.100288},
Key = {fds357858}
}
@article{fds278677,
Author = {Malone, MJ and Baker, PA and Burns, SJ},
Title = {Recrystallization of dolomite: An experimental study from
50-200°C},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {60},
Number = {12},
Pages = {2189-2207},
Publisher = {Elsevier BV},
Year = {1996},
Month = {January},
ISSN = {0016-7037},
url = {http://dx.doi.org/10.1016/0016-7037(96)00062-2},
Abstract = {The recrystallization of dolomite was investigated
experimentally from 50° to 200°C for durations up to
approximately one year. A synthetic, mixed Ca-Mg carbonate
(41.7 mol% MgCO3 and with no observable ordering reflections
on X-ray diffraction patterns) was recrystallized in
solutions with ionic strengths similar to seawater in two
sets of time series experiments. Dolomite recrystallization
reaction rates were initially rapid, but slowed
significantly with duration of the experiments. Reaction
rates were highly temperature dependent. Dolomite completely
recrystallized within 286 hours at 200°C, whereas less than
30% recrystallization was attained in 336 days at 50°C.
Increases in mol% MgCO3 of the recrystallized dolomites were
initially rapid, but slowed with extent of reaction. Despite
complete recrystallization at 200°C, a stoichiometric
dolomite was never achieved (a maximum of 48.6 mol% MgCO3
was attained). Unit cell dimensions, measured by X-ray
diffraction, decreased with increasing extents of
recrystallization and largely responded to changes in
stoichiometry. Increases in cation ordering during
recrystallization lagged behind increases in mol% MgCO3.
Significant increases in cation order were only observed in
the 200°C experiments. Coprecipitation of Sr with dolomite
varied as a function of temperature and degree of
recrystallization. Strontium distribution coefficients, DSr
= (Sr/Ca)recrystallized dolomite/ (Sr/Ca)solution, ranged
from a maximum of 0.22 (8% recrystallization) at 50°C to a
minimum of 0.044 (100% recrystallization) at 200°C. DSr
varied primarily as a function of the extent of
recrystallization, probably due to thermodynamic effects
such as variable stoichiometry and, to a lesser extent,
cation order of the dolomite. Likewise, Na contents of
dolomites decreased with increasing temperature and degree
of recrystallization. The most significant decrease in Na
concentrations occurred rapidly suggesting that Na may be a
sensitive indicator of the early recrystallization
process.},
Doi = {10.1016/0016-7037(96)00062-2},
Key = {fds278677}
}
@article{fds278672,
Author = {MALONE, MJ and BAKER, PA and BURNS, SJ},
Title = {Recrystallization of dolomite: evidence from the Monterey
Formation (Miocene), California},
Journal = {Sedimentology},
Volume = {41},
Number = {6},
Pages = {1223-1239},
Publisher = {WILEY},
Year = {1994},
Month = {January},
url = {http://dx.doi.org/10.1111/j.1365-3091.1994.tb01450.x},
Abstract = {Dolomites from the upper calcareous‐siliceous member of
the Miocene Monterey Formation exposed west of Santa
Barbara, California, were analysed for geochemical, isotopic
and crystallographic variation. The data clearly document
the progressive recrystallization of dolomite during burial
diagenesis in marine pore fluids. Recrystallization is
recognized by the following compositional and
crystallographic variations. Dolomites have decreasing δ18O
and δ13C compositions, decreasing Sr contents and
increasing Mg contents with increasing burial depths and
temperatures from east to west in the study area. δ18O
values vary from 5·3‰ in the east to − 5·5‰ PDB in
the west and are interpreted to reflect the greater extent
and higher temperature of dolomite recrystallization in the
west. δ13C values correlate with δ18O and decrease from
13·6‰ in the east to − 8·7‰ PDB in the west. Sr
concentrations correlate positively with δ18O values and
decrease from a mean of 750 ppm in the east to a mean of 250
ppm in the west. Mol% MgCO3 values inversely correlate with
δ18O values and increase from a minimum of 41·0 in the
east to a maximum of 51·4 in the west. Rietveld refinements
of powder X‐ray diffraction data indicate that the more
recrystallized dolomites have more contracted unit cells and
increased cation ordering. The fraction of the Ca sites in
the dolomites that are occupied by Ca atoms increases
slightly with the approach to stoichiometry. The fraction of
the Mg sites occupied by Mg atoms strongly correlates with
mol% MgCO3. Even in early diagenetic, non‐stoichiometric
dolomites, there is little substitution of Mg in Ca sites.
During recrystallization, the amount of Mg substituting for
Ca in Ca sites decreases even further. Most of the disorder
in the least recrystallized, non‐stoichiometric dolomites
is related to substitution of excess Ca on Mg sites.
Copyright © 1994, Wiley Blackwell. All rights
reserved},
Doi = {10.1111/j.1365-3091.1994.tb01450.x},
Key = {fds278672}
}
@article{fds278721,
Author = {Ballantyne, AP and Baker, PA and Chambers, JQ and Villalba, R and Argollo, J},
Title = {Regional differences in south american monsoon precipitation
inferred from thegrowth and isotopic composition of tropical
trees},
Journal = {Earth Interactions},
Volume = {15},
Number = {5},
Pages = {1-35},
Publisher = {American Meteorological Society},
Year = {2011},
Month = {February},
ISSN = {1087-3562},
url = {http://dx.doi.org/10.1175/2010EI277.1},
Abstract = {The authors present results on the relationship between
treering proxies and regional precipitation for several
sites in tropical South America. The responsiveness of
oxygen isotopes (γ18O) and seasonal growth as precipitation
proxies was first validated by high-resolution sampling of a
Tachigali myrmecophila from Manaus, Brazil (3.1°S,
60.0°W). Monthly growth of Tachigali spp. was significantly
correlated with monthly precipitation. Intra-annual
measurements of cellulose γ18O in Tachigali spp. were also
significantly correlated with monthly precipitation at a lag
of approximately one month. The annual ring widths of two
tropical tree taxa, Cedrela odorata growing in the Amazon
(12.6°S, 69.2°W) and Polylepis tarapacana growing in the
Altiplano (22.0°S, 66.0°W), were validated using
bomb-derived radiocarbon 14C. Estimated dates were within
two to three years of bomb-inferred 14C dates, indicating
that these species exhibit annual rings but uncertainties in
our chronologies remain. A multiproxy record spanning 180
years from Cedrela spp. showed a significant negative
relationship between cellulose γ18O and January
precipitation. A 150-yr record obtained from Polylepis spp.
also showed a significant negative relationship between
γ18O and March precipitation, whereas annual ring width
showed a significant positive correlation with December
precipitation. These proxies were combined in a multivariate
framework to reconstruct past precipitation, revealing a
significant increase in monsoon precipitation at the Amazon
site since 1890 and a significant decrease in monsoon
precipitation at the Altiplano since 1880. Proxy time series
also showed spatial and temporal coherence with
precipitation variability due to El Niño forcing,
suggesting that oxygen isotopes and ring widths in tropical
trees may be important diagnostics for identifying regional
differences in the response of the,tropical hydrologic cycle
to anthropogenic warming, © 2011.},
Doi = {10.1175/2010EI277.1},
Key = {fds278721}
}
@article{fds278670,
Author = {Perkins, RD and Dwyer, GS and Rosoff, DB and Fuller, J and Baker, PA and Lloyd, RM},
Title = {Salina sedimentation and diagenesis: West Caicos Island,
British West Indies},
Journal = {Special Publs. Int. Assoc. Sediment.},
Number = {21},
Pages = {37-54},
Year = {1994},
url = {http://dx.doi.org/10.1002/9781444304077.ch4},
Abstract = {Up to 2.4 m of Holocene sediment have accumulated in an
elongate topographic low (3 km long by 0.5 km wide) bounded
on the west by Pleistocene aeolianite and isolated from
shallow platform waters on the east by a series of oolitic
beach and beach/dune sequences of Holocene age. The salina
is fed by marine groundwaters that primarily seep through
the underlying Pleistocene bedrock. The stratigraphic
succession of the salina indicates a trend towards
increasing marine restriction, grading from marine
wackestones, packstones and grainstones at the base, upward
through microbially laminated mudstones into gypsum mush in
the uppermost part of the section. -from
Authors},
Doi = {10.1002/9781444304077.ch4},
Key = {fds278670}
}
@article{fds278673,
Author = {Rigsby, CA and Zierenberg, RA and Baker, PA},
Title = {Sedimentary and diagenetic structures and textures in
turbiditic and hemiturbiditic strata as revealed by
whole-core X-radiography, Middle Valley, northern Juan de
Fuca Ridge},
Journal = {Proc., Scientific Results, Odp Leg 139, Middle Valley, Juan
De Fuca Ridge},
Pages = {105-111},
Year = {1994},
Month = {January},
url = {http://dx.doi.org/10.2973/odp.proc.sr.139.224.1994},
Abstract = {Reveals primary sedimentary structures in mud-rich units
that allow us to distinguish between mud turbites and
pelagic deposits. They reveal three distinct ichnofauna
assemblages that record depositional environments with
different levels of oxygen and different sedimentation rates
as well as eight major carbonate and pyrite diagenetic
morphologies. The X-radiographs delineate the extent of
metalliferous turbidites and debris flows at Site 856. -from
Authors},
Doi = {10.2973/odp.proc.sr.139.224.1994},
Key = {fds278673}
}
@article{fds278658,
Author = {Shukla, V and Baker, PA},
Title = {Sedimentology and geochemistry of dolostones},
Journal = {Sedimentology and Geochemistry of Dolostones},
Year = {1988},
Month = {December},
Abstract = {This publication is the result of a symposium held in
Raleigh, North Carolina, September 1986. The 18 separately
abstracted papers are arranged into the following
categories: techniques and experimental studies; organogenic
dolomites; dolomites in Mississippi Valley-type ore
deposits; rock-water interactions during dolomitization;
geochemistry of dolomite textures and fabrics; dolomite
diagenesis; and case histories of dolomite origins. A
subject index is included. -A.W.Hall},
Key = {fds278658}
}
@article{fds343227,
Author = {Shukla, V and Baker, PA},
Title = {Sedimentology and geochemistry of dolostones},
Journal = {Sedimentology and Geochemistry of Dolostones},
Year = {1988},
Month = {January},
Abstract = {This publication is the result of a symposium held in
Raleigh, North Carolina, September 1986. The 18 separately
abstracted papers are arranged into the following
categories: techniques and experimental studies; organogenic
dolomites; dolomites in Mississippi Valley-type ore
deposits; rock-water interactions during dolomitization;
geochemistry of dolomite textures and fabrics; dolomite
diagenesis; and case histories of dolomite origins. A
subject index is included. -A.W.Hall},
Key = {fds343227}
}
@article{fds350575,
Author = {Shukla, V and Baker, PA},
Title = {Sedimentology and geochemistry of dolostones},
Journal = {Sedimentology and Geochemistry of Dolostones},
Year = {1988},
Month = {January},
url = {http://dx.doi.org/10.2110/pec.88.43},
Abstract = {This publication is the result of a symposium held in
Raleigh, North Carolina, September 1986. The 18 separately
abstracted papers are arranged into the following
categories: techniques and experimental studies; organogenic
dolomites; dolomites in Mississippi Valley-type ore
deposits; rock-water interactions during dolomitization;
geochemistry of dolomite textures and fabrics; dolomite
diagenesis; and case histories of dolomite origins. A
subject index is included. -A.W.Hall},
Doi = {10.2110/pec.88.43},
Key = {fds350575}
}
@article{fds278635,
Author = {Zell, C and Kim, JH and Hollander, D and Lorenzoni, L and Baker, P and Silva, CG and Nittrouer, C and Sinninghe Damsté,
JS},
Title = {Sources and distributions of branched and isoprenoid
tetraether lipids on the Amazon shelf and fan: Implications
for the use of GDGT-based proxies in marine
sediments},
Journal = {Geochimica Et Cosmochimica Acta},
Volume = {139},
Pages = {293-312},
Publisher = {Elsevier BV},
Year = {2014},
Month = {August},
ISSN = {0016-7037},
url = {http://dx.doi.org/10.1016/j.gca.2014.04.038},
Abstract = {Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in
river fan sediments have been used successfully to
reconstruct mean annual air temperature (MAAT) and soil pH
of the Congo River drainage basin. However, in a previous
study of Amazon deep-sea fan sediments the reconstructed
MAATs were ca. 10°C colder than the actual MAAT of the
Amazon basin. In this study we investigated this apparent
offset, by comparing the concentrations and distributions of
brGDGTs in Amazon River suspended particulate matter (SPM)
and sediments to those in marine SPM and surface sediments.
The riverine brGDGT input was evident from the elevated
brGDGT concentrations in marine SPM and surface sediments
close to the river mouth. The distributions of brGDGTs in
marine SPM and sediments varied widely, but generally showed
a higher relative abundance of methylated and cyclic brGDGTs
than those in the river. Since this difference in brGDGT
distribution was also found in intact polar lipid
(IPL)-derived brGDGTs, which were more recently produced,
the change in the marine brGDGT distribution was most likely
due to marine in situ production. Consequently, the MAATs
calculated based on the methylation of branched tetraethers
(MBT) and the cyclisation of branched tetraethers (CBT) were
lower and the CBT-derived pH values were higher than those
of the Amazon basin. However, SPM and sediments from
stations close to the river mouth still showed MBT/CBT
values that were similar to those of the river. Therefore,
we recommend caution when applying the MBT/CBT proxy, it
should only be used in sediment cores that were under high
river influence. The influence of riverine derived
isoprenoid GDGT (isoGDGT) on the isoGDGT-based TEX86
temperature proxy was also examined in marine SPM and
sediments. An input of riverine isoGDGTs from the Amazon
River was apparent, but its influence on the marine TEX86
was minor since the TEX86 of SPM in the Amazon River was
similar to that in the marine SPM and sediments. © 2014 The
Authors.},
Doi = {10.1016/j.gca.2014.04.038},
Key = {fds278635}
}
@article{fds349311,
Author = {Liu, X and Battisti, DS and White, RH and Baker, PA},
Title = {South American climate during the early Eocene: Impact of a
narrower Atlantic and higher atmospheric
CO
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