Scholars@Duke
Paul A. Baker

Paul A. Baker

Professor Emeritus of Earth and Climate Science
Earth and Climate Sciences
pbaker@duke.edu
Box 90328, Durham, NC 27708
9 Circuit Drive, 5116 Grainger Hall, Durham, NC 27708

Selected Publications

Paleolimnological responses of Ecuadorian páramo lakes to local and regional stressors over the last two millennia

Journal Article Journal of Paleolimnology · April 1, 2023 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 i ... Full text Cite

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 Article Journal of Paleolimnology · April 1, 2023 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. ... Full text Cite

A 1.8 million year history of Amazon vegetation

Journal Article Quaternary Science Reviews · January 1, 2023 During the Pleistocene, long-term trends in global climate were controlled by orbital cycles leading to high amplitude glacial-interglacial variability. The history of Amazonian vegetation during this period is largely unknown since no continuous record fr ... Full text Cite

Holocene variations in Lake Titicaca water level and their implications for sociopolitical developments in the central Andes.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · January 2023 Holocene climate in the high tropical Andes was characterized by both gradual and abrupt changes, which disrupted the hydrological cycle and impacted landscapes and societies. High-resolution paleoenvironmental records are essential to contextualize archae ... Full text Cite

The challenges and potential of geogenomics for biogeography and conservation in Amazonia

Journal Article Journal of Biogeography · October 1, 2022 Amazonia has a very high, although still incompletely known, species diversity distributed over a mosaic of heterogeneous habitats that are also poorly characterized. As a result of this multi-faceted complexity, Amazonia poses a great challenge to geogeno ... Full text Cite

Extended-Range Luminescence Dating of Central and Eastern Amazonia Sandy Terrains

Journal Article Frontiers in Earth Science · July 6, 2022 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 ec ... Full text Cite

Climatic Controls on a Holocene Mercury Stable Isotope Sediment Record of Lake Titicaca

Journal Article ACS Earth and Space Chemistry · February 17, 2022 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 r ... Full text Cite

Ecological resilience in tropical Andean lakes: A paleolimnological perspective

Journal Article Limnology and Oceanography · February 1, 2022 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 ... Full text Cite

Biochronostratigraphy of the western equatorial Atlantic for the last 1.93 Ma

Journal Article Quaternary International · October 10, 2021 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 ... Full text Cite

Negligible Quantities of Particulate Low-Temperature Pyrogenic Carbon Reach the Atlantic Ocean via the Amazon River.

Journal Article Global biogeochemical cycles · September 2021 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 marke ... Full text Cite

Reconstructing two millennia of copper and silver metallurgy in the Lake Titicaca region (Bolivia/Peru) using trace metals and lead isotopic composition

Journal Article Anthropocene · June 1, 2021 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 ... Full text Cite

Vulnerability of the biota in riverine and seasonally flooded habitats to damming of Amazonian rivers

Journal Article Aquatic Conservation: Marine and Freshwater Ecosystems · May 1, 2021 The extent and intensity of impacts of multiple new dams in the Amazon basin on specific biological groups are potentially large, but still uncertain and need to be better understood. It is known that river disruption and regulation by dams may affect sedi ... Full text Cite

The Rise and Fall of Wiñaymarka: Rethinking Cultural and Environmental Interactions in the Southern Basin of Lake Titicaca

Journal Article Human Ecology · April 1, 2021 Investigations of how past human societies managed during times of major climate change can inform our understanding of potential human responses to ongoing environmental change. In this study, we evaluate the impact of environmental variation on human com ... Full text Cite

South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2

Journal Article Journal of Climate · January 15, 2020 The Cenozoic climate of tropical South America was fundamental to the development of its biota, the most biodiverse on Earth. No previous studies have explicitly addressed how the very different atmospheric composition and Atlantic geometry during the earl ... Full text Cite

Paleoclimate of the subtropical Andes during the latest Miocene, Lauca Basin, Chile

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · November 15, 2019 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 sedimenta ... Full text Cite

Modern and late Pleistocene particulate organic carbon transport by the Amazon River: Insights from long-chain alkyl diols

Journal Article Geochimica et Cosmochimica Acta · October 1, 2019 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 reflecti ... Full text Cite

Parvimico materdei gen. et sp. nov.: A new platyrrhine from the Early Miocene of the Amazon Basin, Peru.

Journal Article Journal of human evolution · September 2019 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 roden ... Full text Open Access Cite

Late Holocene volcanic and anthropogenic mercury deposition in the western Central Andes (Lake Chungará, Chile).

Journal Article The Science of the total environment · April 2019 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, ... Full text Cite

Lake-level variability in Salar de Coipasa, Bolivia during the past ∼40,000 yr

Conference Quaternary Research (United States) · March 1, 2019 Various paleoclimatic records have been used to reconstruct the hydrologic history of the Altiplano, relating this history to past variability of the South American summer monsoon. Prior studies of the southern Altiplano, the location of the world's larges ... Full text Cite

IntCal, SHCal, or a Mixed Curve? Choosing a 14C Calibration Curve for Archaeological and Paleoenvironmental Records from Tropical South America

Journal Article Radiocarbon · June 1, 2018 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 reve ... Full text Cite

New Early Miocene primate bearing faunal assemblage from the Alto Madre de Dios, Peru

Conference AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY · April 1, 2018 Link to item Cite

Twenty-three-year timeline of ecological stable states and regime shifts in upper Amazon oxbow lakes

Journal Article Hydrobiologia · February 1, 2018 Regime shifts in shallow lakes are often associated with anthropogenic impacts, such as land-use change, non-point source nutrient loading, and overfishing. These shifts have mostly been examined in lakes in temperate and boreal regions and within anthropo ... Full text Cite

Punctuated changes in the morphology of an endemic diatom from Lake Titicaca

Journal Article Paleobiology · February 1, 2018 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 clim ... Full text Cite

A ∼6000 yr diatom record of mid- to late Holocene fluctuations in the level of Lago Wiñaymarca, Lake Titicaca (Peru/Bolivia)

Journal Article Quaternary Research (United States) · September 1, 2017 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 unco ... Full text Cite

Damming the rivers of the Amazon basin.

Journal Article Nature · June 2017 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, ... Full text Cite

Origin and processing of terrestrial organic carbon in the Amazon system: Lignin phenols in river, shelf, and fan sediments

Journal Article Biogeosciences · May 17, 2017 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 ... Full text Cite

Damming the Rivers of the Amazon Basin

Journal Article Nature · 2017 Cite

Origin, transport and deposition of leaf-wax biomarkers in the Amazon Basin and the adjacent Atlantic

Journal Article Geochimica et Cosmochimica Acta · November 1, 2016 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 c ... Full text Cite

Trans-Amazon Drilling Project (TADP): Origins and evolution of the forests, climate, and hydrology of the South American tropics

Journal Article Scientific Drilling · December 17, 2015 This article presents the scientific rationale for an ambitious ICDP drilling project to continuously sample Late Cretaceous to modern sediment in four different sedimentary basins that transect the equatorial Amazon of Brazil, from the Andean foreland to ... Full text Cite

Nature and causes of Quaternary climate variation of tropical South America

Journal Article Quaternary Science Reviews · September 5, 2015 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 ... Full text Cite

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 Article Earth and Planetary Science Letters · December 15, 2014 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 s ... Full text Cite

The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · December 1, 2014 Reconstructions of surface paleoceanographic conditions of the western equatorial Atlantic and past climates of the adjacent Northeast Brazilian (the "Nordeste") continental margin were undertaken by analyzing sediments from a piston core and associated gr ... Full text Cite

Climate variability and ice-sheet dynamics during the last three glaciations

Journal Article Earth and Planetary Science Letters · November 5, 2014 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 ... Full text Cite

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 Article Geochimica et Cosmochimica Acta · August 15, 2014 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 ... Full text Cite

The emerging field of geogenomics: Constraining geological problems with genetic data

Journal Article Earth-Science Reviews · January 1, 2014 The development of a genomics-derived discipline within geology is timely, as a result of major advances in acquiring and processing geologically relevant genetic data. This paper articulates the emerging field of "geogenomics", which involves the use of l ... Full text Cite

Evolution of the Lake Titicaca basin and its diatom flora over the last ~370,000 years

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · February 1, 2012 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 th ... Full text Cite

Caribbean hydrological variability during the Holocene as reconstructed from crater lakes on the island of Grenada

Journal Article Journal of Quaternary Science · November 1, 2011 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 p ... Full text Cite

Climate-mediated nitrogen and carbon dynamics in a tropical watershed

Journal Article Journal of Geophysical Research · May 18, 2011 Full text Cite

A 370,000-year record of vegetation and fire history around Lake Titicaca (Bolivia/Peru)

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · May 15, 2011 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 di ... Full text Cite

Regional differences in south american monsoon precipitation inferred from thegrowth and isotopic composition of tropical trees

Journal Article Earth Interactions · February 1, 2011 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 b ... Full text Cite

Impact of two different types of El Niño events on the Amazon climate and ecosystem productivity

Journal Article Journal of Plant Ecology · 2011 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 ... Full text Cite

Geologic constraints on rain-fed Qocha reservoir agricultural infrastructure, northern Lake Titicaca Basin, Peru

Journal Article Journal of Archaeological Science · January 1, 2011 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 s ... Full text Cite

Millennial-scale climate variability during the Last Glacial period in the tropical Andes

Journal Article Quaternary Science Reviews · April 1, 2010 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 ... Full text Cite

Climatic and environmental controls on the occurrence and distributions of long chain alkenones in lakes of the interior United States

Journal Article Geochimica et Cosmochimica Acta · March 1, 2010 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 Neb ... Full text Cite

Impacts of the two types of El Nino Events on the Amazon forest

Journal Article Journal of Plant Ecology · 2010 Cite

Late Quaternary Paleohydrology of the Madre de Dios River, southwestern Amazon Basin, Peru

Journal Article Geomorphology · December 15, 2009 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. T ... Full text Cite

Geomorphology of Natural Hazards and Human-induced Disasters in Bolivia

Journal Article Developments in Earth Surface Processes · December 1, 2009 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 soun ... Full text Cite

Paleo-precipitation indicators

Chapter · January 1, 2009 Full text Cite

Paleolimnological evidence of the effects on lakes of energy and mass transfer from climate and humans

Journal Article Limnology and Oceanography · January 1, 2009 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 conceptu ... Full text Cite

Extreme drought events revealed in Amazon tree ring records

Journal Article Geophysical Research Letters · 2009 Cite

Holocene multidecadal- to millennial-scale hydrologic variability on the South American Altiplano

Journal Article Holocene · September 1, 2008 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 ... Full text Cite

Quaternary glaciation and hydrologic variation in the South American tropics as reconstructed from the Lake Titicaca drilling project

Journal Article Quaternary Research · January 1, 2007 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 continuousl ... Full text Cite

Pliocene Arctic temperature constraints from the growth rings and isotopic composition of fossil larch

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · December 8, 2006 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 ... Full text Cite

Spatial and temporal variation in cores from Lake Titicaca, Bolivia/Peru during the last 13,000 yrs

Journal Article Quaternary International · December 1, 2006 We compared the stratigraphy of sediment cores that span the last 13,000 yrs from three sites in the main basin of Lake Titicaca, Boliva/Peru as indicators of regional paleoclimate. The cores show similar patterns of change after ∼6400 calendar yrs before ... Full text Cite

Holocene hydrologic variation at Lake Titicaca, Bolivia/Peru, and its relationship to North Atlantic climate variation

Journal Article Journal of Quaternary Science · October 1, 2005 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) thes ... Full text Cite

Late Quaternary palaeolakes, rivers, and wetlands on the Bolivian Altiplano and their palaeoclimatic implications

Journal Article Journal of Quaternary Science · October 1, 2005 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 ... Full text Cite

Meta-analysis of tropical surface temperatures during the Last Glacial Maximum

Journal Article Geophysical Research Letters · March 16, 2005 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 e ... Full text Cite

Mid-Pliocene deep-sea bottom-water temperatures based on ostracode Mg/Ca ratios

Journal Article Marine Micropaleontology · January 1, 2005 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 wat ... Full text Open Access Cite

Vegetation and climate change on the Bolivian Altiplano between 108,000 and 18,000 yr ago

Journal Article Quaternary Research · January 1, 2005 A 90,000-yr record of environmental change before 18,000 cal yr B.P. has been constructed using pollen analyses from a sediment core obtained from Salar de Uyuni (3653 m above sea level) on the Bolivian Altiplano. The sequence consists of alternating mud a ... Full text Cite

Hydrologic variation during the last 170,000 years in the southern hemisphere tropics of South America

Journal Article Quaternary Research · January 1, 2004 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 ... Full text Open Access Cite

A vegetation and fire history of Lake Titicaca since the last glacial maximum

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · May 15, 2003 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 ... Full text Cite

A late quaternary diatom record of tropical climatic history from Lake Titicaca (Peru and Bolivia)

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · May 15, 2003 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 millenni ... Full text Cite

Fluvial history of the Rio Ilave valley, Peru, and its relationship to climate and human history

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · May 15, 2003 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 ... Full text Cite

Application of strontium isotopes to understanding the hydrology and paleohydrology of the Altiplano, Bolivia-Peru

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · May 15, 2003 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 be ... Full text Cite

Late Quaternary lake-level changes constrained by radiocarbon and stable isotope studies on sediment cores from Lake Titicaca, South America

Journal Article Global and Planetary Change · January 1, 2003 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 ... Full text Cite

Geochemistry of fluid phases and sediments: Relevance to hydrothermal circulation in Middle Valley, ODP Legs 139 and 169

Journal Article Applied Geochemistry · November 1, 2002 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 ... Full text Cite

Hydrothermal geochemistry of sediments and pore waters in Escanaba Trough - ODP Leg 169

Journal Article Applied Geochemistry · November 1, 2002 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 ... Full text Cite

Early deglaciation in the tropical Andes - Response

Journal Article SCIENCE · October 4, 2002 Link to item Cite

Ocean paleotemperatures from ostracode Mg/Ca ratios

Conference GEOCHIMICA ET COSMOCHIMICA ACTA · August 1, 2002 Link to item Cite

Early warming of tropical South America at the last glacial-interglacial transition.

Journal Article Science (New York, N.Y.) · May 2002 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 subs ... Full text Cite

Late-Quaternary lowstands of Lake Titicaca: Evidence from high-resolution seismic data

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · April 15, 2002 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 ... Full text Cite

Paleoclimate. Trans-Atlantic climate connections.

Journal Article Science (New York, N.Y.) · April 2002 Full text Cite

Insolation, moisture balance and climate change on the South American Altiplano since the Last Glacial Maximum

Journal Article Climatic Change · February 26, 2002 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 ... Full text Cite

Trace elements in marine ostracodes

Chapter · January 1, 2002 Extending the work of Cadot, Kaesler, De Deckker, Chivas, and Corrège, we have measured the elemental chemistry of shells of marine ostracodes to evaluate the usefulness of ostracode shell chemistry as a paleoenvironmental proxy. Our work has focused prima ... Full text Cite

Lake Titicaca: An archive of South American paleoclimate

Journal Article Geotimes · December 1, 2001 Cite

Tropical climate changes at millennial and orbital timescales on the Bolivian Altiplano.

Journal Article Nature · February 2001 Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation). Although this area plays a key role in global climate cycles, little is known abo ... Full text Cite

The history of South American tropical precipitation for the past 25,000 years.

Journal Article Science (New York, N.Y.) · January 2001 Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last ... Full text Cite

Late quaternary climate and hydrology of tropical South America inferred from an isotopic and chemical model of Lake Titicaca, Bolivia and Peru

Journal Article Quaternary Research · January 1, 2001 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 ... Full text Cite

Changes in North Atlantic deep-sea temperature during climatic fluctuations of the last 25,000 years based on ostracode Mg/Ca ratios

Journal Article Geochemistry, Geophysics, Geosystems · December 1, 2000 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 var ... Full text Open Access Cite

Orbital and suborbital variability in North Atlantic bottom water temperature obtained from deep-sea ostracod Mg/Ca ratios

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · September 15, 2000 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 ov ... Full text Open Access Cite

A new estimate of the Holocene lowstand level of Lake Titicaca, central Andes, and implications for tropical palaeohydrology

Journal Article Holocene · January 1, 2000 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 ... Full text Cite

Temperature dependence of the strontium distribution coefficient in calcite: An experimental study from 40° to 200°c and application to natural diagenetic calcites

Journal Article Journal of Sedimentary Research · January 1, 1999 The temperature dependence of Sr coprecipitation with calcite was determined experimentally in solutions with Sr/Ca ratios and ionic strengths closely resembling marine pore fluids. Aragonite-to-calcite and dolomite-to-calcite transformations were conducte ... Full text Cite

The deep structure of a sea-floor hydrothermal deposit

Journal Article Nature · April 2, 1998 Hydrothermal circulation at the crests of mid-ocean ridges plays an important role in transferring heat from the interior of the Earth. A consequence of this hydrothermal circulation is the formation of metallic ore bodies known as volcanic-associated mass ... Full text Cite

High-resolution seismic reflection profiles from Lake Titicaca, Peru-Bolivia: Evidence for Holocene aridity in the tropical Andes

Journal Article Geology · 1998 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 lev ... Full text Cite

High-resolution seismic reflection profiles from Lake Titicaca, Peru-Bolivia: Evidence for Holocene aridity in the tropical Andes

Journal Article Geology · 1998 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 lev ... Full text Cite

Deep-sea ostracode shell chemistry (Mg:Ca ratios) and Late Quaternary Arctic Ocean history

Journal Article Geological Society Special Publication · December 1, 1996 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 ... Full text Cite

Hydrothermal dolomitization and recrystallization of dolomite breccias from the Miocene Monterey formation, Tepusquet area, California

Journal Article Journal of Sedimentary Research · September 1, 1996 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 ... Full text Cite

Recrystallization of dolomite: An experimental study from 50-200°C

Journal Article Geochimica et Cosmochimica Acta · January 1, 1996 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) w ... Full text Cite

Deep-sea ostracode shell chemistry (Mg:Ca ratios) and late Quaternary Arctic Ocean history

Journal Article Late Quaternary palaeoceanography of the North Atlantic margins · January 1, 1996 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 ... Cite

North atlantic deepwater temperature change during late pliocene and late quaternary climatic cycles

Journal Article Science · November 24, 1995 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° ... Open Access Cite

Salina sedimentation and diagenesis: West Caicos Island, British West Indies

Journal Article Special Publs. Int. Assoc. Sediment. · 1994 Cite

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 Article Proc., scientific results, ODP Leg 139, Middle Valley, Juan de Fuca Ridge · January 1, 1994 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 dif ... Full text Cite

Recrystallization of dolomite: evidence from the Monterey Formation (Miocene), California

Journal Article Sedimentology · January 1, 1994 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 recrystalliz ... Full text Cite

Geochemistry of carbonate nodules and cements and implications for hydrothermal circulation, Middle Valley, Juan de Fuca Ridge

Journal Article Proc., scientific results, ODP Leg 139, Middle Valley, Juan de Fuca Ridge · January 1, 1994 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) ... Full text Cite

A note on the carbon, sulfur, and nitrogen contents of hydrothermally altered sediments, Middle Valley, Juan de Fuca Ridge

Journal Article Proc., scientific results, ODP Leg 139, Middle Valley, Juan de Fuca Ridge · January 1, 1994 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 o ... Full text Cite

EXPERIMENTAL AND NATURAL MIMETIC DOLOMITIZATION OF ARAGONITE OOIDS

Journal Article Journal of Sedimentary Research · July 1, 1993 To better understand fabrics in dolomitized carbonates, ara-gonitic ooids were replaced with dolomite in laboratory experiments. Recent ooids from Cat Cay were reacted in a solution of 0.S M MgCI, and 0.4 M CaCl2 in Teflon-lined stainless steel bombs at 20 ... Full text Cite

Timing of carbonate mineral precipitation and fluid flow in sea- floor basalts, northwest Indian Ocean

Journal Article Geology · January 1, 1992 The strontium isotope ratios of authigenic carbonates from sea-floor basalts have been determined. The samples include calcites from 57.2 Ma crust from Ocean Drilling Project (ODP) Site 715, and calcites, aragonites, and siderites from 63.7 Ma crust from O ... Full text Cite

Timing of carbonate mineral precipitation and fluid flow in sea- floor basalts, northwest Indian Ocean

Journal Article Geology · 1992 The strontium isotope ratios of authigenic carbonates from sea-floor basalts have been determined. The samples include calcites from 57.2 Ma crust from Ocean Drilling Project (ODP) Site 715, and calcites, aragonites, and siderites from 63.7 Ma crust from O ... Cite

Timing of carbonate mineral precipitation and fluid flow in sea- floor basalts, northwest Indian Ocean

Journal Article Geology · 1992 The strontium isotope ratios of authigenic carbonates from sea-floor basalts have been determined. The samples include calcites from 57.2 Ma crust from Ocean Drilling Project (ODP) Site 715, and calcites, aragonites, and siderites from 63.7 Ma crust from O ... Full text Cite

Surface sediment carbonate mineralogy and water column chemistry: Nicaragua Rise versus the Bahamas

Journal Article Marine Geology · January 1, 1991 Periplatform surface sediments were studied for carbonate mineralogy in conjunction with analyses of the water column for carbonate chemistry on the eastern Northern Nicaragua Rise (NNR) in the Caribbean Sea. The results show a strong correspondence betwee ... Full text Cite

Large-scale lateral advection of seawater through oceanic crust in the central equatorial Pacific

Journal Article Earth and Planetary Science Letters · January 1, 1991 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 sedi ... Full text Cite

Cenozoic marine sedimentation in the Sechura and Pisco basins, Peru

Journal Article Palaeogeography, Palaeoclimatology, Palaeoecology · January 1, 1990 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 S ... Full text Cite

Geochemistry of secondary carbonates in Leg 115 basalts: tracers of basalt/seawater interaction

Journal Article Proc., scientific results, ODP, Leg 115, Mascarene Plateau · January 1, 1990 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 pr ... Full text Cite

Occurrence of dolomite in Neogene phosphatic sediments

Journal Article Phosphate deposits of the world, vol. 3. Neogene to Modern phosphorites · January 1, 1990 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. Phosph ... Cite

Geochemistry of periplatform carbonate sediments, Leg 115, Site 716 Maldives Archipelago, (Indian Ocean)

Journal Article Proc., scientific results, ODP, Leg 115, Mascarene Plateau · January 1, 1990 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 ... Full text Cite

Minor element and stable isotopic composition of the carbonate fine fraction: Site 709, Indian Ocean

Journal Article Proc., scientific results, ODP, Leg 115, Mascarene Plateau · January 1, 1990 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 betwe ... Full text Cite

Sedimentology and geochemistry of dolostones

Journal Article Sedimentology and geochemistry of dolostones · December 1, 1988 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 Mississi ... Cite

Late Eocene diatomite from the Peruvian coastal desert, coastal upwelling in the eastern Pacific, and Pacific circulation before the terminal Eocene event

Journal Article Geology · 1988 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 la ... Full text Cite

Late Eocene diatomite from the Peruvian coastal desert, coastal upwelling in the eastern Pacific, and Pacific circulation before the terminal Eocene event

Journal Article Geology · 1988 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 la ... Full text Cite

Sedimentology and geochemistry of dolostones

Journal Article Sedimentology and geochemistry of dolostones · January 1, 1988 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 Mississi ... Cite

Sedimentology and geochemistry of dolostones

Journal Article Sedimentology and geochemistry of dolostones · January 1, 1988 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 Mississi ... Full text Cite

The origin of celestite in deep-sea carbonate sediments

Journal Article Geochimica et Cosmochimica Acta · January 1, 1988 Several celestite nodules were recovered on DSDP Leg 90 from four drilling sites on the Lord Howe Rise, southwest Pacific Ocean. The sediments at these sites are predominantly very pure calcareous nannofossil oozes and chalks. As a result of a higher-than ... Full text Cite

The factors controlling the formation and chemistry of dolomite in organic-rich sediments: Miocene Drakes Bay formation, California

Journal Article Sedimentology and geochemistry of dolostones · January 1, 1988 These siliceous mudstones contain many small dolomite nodules, probably formed without a precursor biogenic calcite supplying Ca or HCO3- for dolomitization. Dolomite formation preferentially took place in sediment layers slightly richer in organic C than ... Full text Cite

A geochemical study of dolomite in the Monterey Formation, California.

Journal Article Journal of Sedimentary Petrology · January 1, 1987 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 iro ... Full text Cite

Distribution and character of pale green laminae in sediment from Lord Howe Rise: a probable late Neogene and Quaternary tephrostratigraphic record.

Journal Article Initial reports DSDP, Leg 90, Noumea, New Caledonia to Wellington, New Zealand. Part 2 · January 1, 1986 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 c ... Full text Cite

Pore-water chemistry of carbonate-rich sediments, Lord Howe Rise, southwest Pacific Ocean.

Journal Article Initial reports DSDP, Leg 90, Noumea, New Caledonia to Wellington, New Zealand. Part 2 · January 1, 1986 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 ... Full text Cite

Palaeotectonic implications of increased late Eocene-early Oligocene volcanism from South Pacific DSDP sites

Journal Article Nature · December 1, 1985 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 vo ... Full text Cite

Occurrence and formation of dolomite in organic-rich continental margin sediments.

Journal Article Bulletin, American Association of Petroleum Geologists · January 1, 1985 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. ... Cite

EXPERIMENTAL HYDROTHERMAL DEDOLOMITIZATION

Conference AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS · January 1, 1984 Link to item Cite

Diagenesis of carbonates in deep-sea sediments-evidence from sr/ca ratios and interstitial dissolved sr 2 data t

Journal Article Journal of Sedimentary Research · March 1, 1982 Laboratory determinations of the distribution coefficient of strontium in calcite (ks,) have confumed the earlier results of Katz et al. (1972). In addition, we observed that at higher concentrations of strontium, values of ksr were somewhat lowered. Chemi ... Full text Cite

87Sr 86Sr and 18O 16O ratios, interstitial water chemistry and diagenesis in deep-sea carbonate sediments of the Ontong Java Plateau

Journal Article Geochimica et Cosmochimica Acta · January 1, 1982 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 fo ... Full text Cite

87Sr 86Sr and 18O 16O ratios, interstitial water chemistry and diagenesis in deep-sea carbonate sediments of the Ontong Java Plateau

Journal Article Geochimica et Cosmochimica Acta · 1982 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 fo ... Cite

Constraints on the formation of sedimentary dolomite

Journal Article Science · January 1, 1981 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) insub ... Full text Cite

Pressure solution and hydrothermal recrystallization of carbonate sediments — An experimental study

Journal Article Marine Geology · January 1, 1980 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, we ... Full text Cite

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 Article Geochimica et Cosmochimica Acta · January 1, 1976 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 ... Full text Cite

Coral growth rate: Variation with depth

Journal Article Earth and Planetary Science Letters · January 1, 1975 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 ... Full text Cite

Coral growth rate: Variation with depth

Journal Article Physics of the Earth and Planetary Interiors · January 1, 1975 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 ... Full text Cite