Journal ArticleJournal 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 ...
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Journal ArticleJournal 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. ...
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Journal ArticleQuaternary 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 textCite
Journal ArticleProceedings 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticleFrontiers 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 textCite
Journal ArticleACS 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 textCite
Journal ArticleLimnology 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 textCite
Journal ArticleQuaternary 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 textCite
Journal ArticleGlobal 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 textCite
Journal ArticleAnthropocene · 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 textCite
Journal ArticleAquatic 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 textCite
Journal ArticleHuman 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticlePalaeogeography, 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 textCite
Journal ArticleGeochimica 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleThe 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 textCite
ConferenceQuaternary 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 textCite
Journal ArticleRadiocarbon · 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticleQuaternary 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 textCite
Journal ArticleProceedings 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticleFrontiers 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 textCite
Journal ArticleACS 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 textCite
Journal ArticleLimnology 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 textCite
Journal ArticleQuaternary 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 textCite
Journal ArticleGlobal 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 textCite
Journal ArticleAnthropocene · 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 textCite
Journal ArticleAquatic 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 textCite
Journal ArticleHuman 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 textCite
Journal ArticleJournal 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 textCite
Journal ArticlePalaeogeography, 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 textCite
Journal ArticleGeochimica 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 textCite
Journal ArticleJournal 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 textOpen AccessCite
Journal ArticleThe 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 textCite
ConferenceQuaternary 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 textCite
Journal ArticleRadiocarbon · 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 textCite
Journal ArticleHydrobiologia · 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 ...
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Journal ArticlePaleobiology · 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleNature · 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, ...
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Journal ArticleBiogeosciences · 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleScientific 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleEarth 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleEarth 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleEarth-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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleEarth 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleGeomorphology · 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 ...
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Journal ArticleDevelopments 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 ...
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Journal ArticleLimnology 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 ...
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Journal ArticleHolocene · 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleGeophysical 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 ...
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Journal ArticleMarine 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleGlobal 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 ...
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Journal ArticleApplied 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 ...
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Journal ArticleApplied 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 ...
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Journal ArticleScience (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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleClimatic 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 ...
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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 ...
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Journal ArticleNature · 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 ...
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Journal ArticleScience (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 ...
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Journal ArticleQuaternary 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 ...
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Journal ArticleGeochemistry, 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleHolocene · 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleNature · 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleGeological 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleLate 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
Journal ArticleScience · 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° ...
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Journal ArticleProc., 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 ...
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Journal ArticleSedimentology · 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 ...
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Journal ArticleProc., 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) ...
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Journal ArticleProc., 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleMarine 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 ...
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Journal ArticleEarth 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 ...
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Journal ArticlePalaeogeography, 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 ...
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Journal ArticleProc., 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 ...
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Journal ArticlePhosphate 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 ...
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Journal ArticleProc., 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 ...
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Journal ArticleProc., 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 ...
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Journal ArticleSedimentology 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleGeology · 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 ...
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Journal ArticleSedimentology 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 ...
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Journal ArticleSedimentology 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleSedimentology 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 ...
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Journal ArticleJournal 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 ...
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Journal ArticleInitial 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 ...
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Journal ArticleInitial 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 ...
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Journal ArticleNature · 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 ...
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Journal ArticleBulletin, 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. ...
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Journal ArticleJournal 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleScience · 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 ...
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Journal ArticleMarine 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 ...
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Journal ArticleGeochimica 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 ...
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Journal ArticleEarth 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 ...
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Journal ArticlePhysics 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 ...
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