We present the reconstruction of the lake level fluctuation history from Lake El'gygytgyn located... more We present the reconstruction of the lake level fluctuation history from Lake El'gygytgyn located in central Chukotka, Russian Arctic. Lake El'gygytgyn was a subject of an international drilling project that resulted in recovering the longest paleoclimate and paleoenvironmental record of the terrestrial Arctic embracing the last 3.6 million years. Based on lithological and palynological studies and age determinations of shallow lake sediment cores and subaerial lake terraces, we have reconstructed lake level changes back to MIS 7. The reconstructed lake level history shows abrupt rising during glacial-interglacial transitions (MIS 6 to MIS 5 and MIS 2 to MIS 1) and smoother changes during the MIS 4 to MIS 3 stadial-interstadial transition. The most prominent low-level stands are reconstructed for glacial periods, which are associated with a permanent lake ice cover (i.e. MIS 6, 4 and 2). Late Glacial and Holocene lake level changes show a good correlation with changes in precipitation. Milankovic driven insolation changes likely control the permanent or seasonal character of the lake ice cover and is the main driving factor for the long-term level oscillations in the glacial-interglacial cycles. During periods of seasonal ice cover, the lake level fluctuations had the smaller amplitude depending mostly on changes in precipitation. Thus, Lake El'gygytgyn level changes are climate driven and sensitive to both precipitation and temperature.
INDONESIA AND IMPLICATIONS FOR MAFIC LACUSTRINE SEDIMENTS IN GALE CRATER, MARS. R. Y. Sheppard1*,... more INDONESIA AND IMPLICATIONS FOR MAFIC LACUSTRINE SEDIMENTS IN GALE CRATER, MARS. R. Y. Sheppard1*, R. E. Milliken1, J. M. Russell1, M. D. Dyar2,3, E. C. Sklute3, S. Bijaksana4, M. Melles5, and H. Vogel6. 1Dept. Earth, Environmental, and Planetary Sciences, Brown University, 2Dept. Astronomy, Mt. Holyoke College, 3Planetary Science Institute, 4Institut Teknologi Bandung, 5Institute of Geology and Mineralogy, University of Cologne, 6Institute of Geological Sciences & Oeschger Centre for Climate Change Research, University of Bern.
Deposition of ferruginous sediment was widespread during the Archaean and Proterozoic Eons, playi... more Deposition of ferruginous sediment was widespread during the Archaean and Proterozoic Eons, playing an important role in global biogeochemical cycling. Knowledge of organic matter mineralization in such sediment, however, remains mostly conceptual, as modern ferruginous analogs are largely unstudied. Here we show that in sediment of ferruginous Lake Towuti, Indonesia, methanogenesis dominates organic matter mineralization despite highly abundant reactive ferric iron phases like goethite that persist throughout the sediment. Ferric iron can thus be buried over geologic timescales even in the presence of labile organic carbon. Coexistence of ferric iron with millimolar concentrations of methane further demonstrates lack of iron-dependent methane oxidation. With negligible methane oxidation, methane diffuses from the sediment into overlying waters where it can be oxidized with oxygen or escape to the atmosphere. In low-oxygen ferruginous Archaean and Proterozoic oceans, therefore, sedi...
Iron is the most abundant redox‐sensitive element on the Earth's surface, and the oxidation s... more Iron is the most abundant redox‐sensitive element on the Earth's surface, and the oxidation state, mineral host, and crystallinity of Fe‐rich phases in sedimentary systems can record details of water‐rock interactions and environmental conditions. However, we lack a complete understanding of how these Fe‐rich materials are created, maintained, and oxidized or reduced in sedimentary environments, particularly those with mafic sources. The catchment of Lake Towuti, Indonesia, is known to contain a wide range of abundant crystalline Fe oxide, and the lake has a long sedimentary history. Here, we study a ∼100 m long drill core from the lake to understand patterns of sedimentation and how young iron‐rich sediments are affected by diagenesis through geologic time. We use visible/near infrared and Mössbauer spectroscopy, X‐ray diffraction, bulk chemistry measurements, and statistical cluster analysis to characterize the core sediment. We find that the core sediment can be divided into ...
of the subtropical region of South America (i.e., the transition between the tropics and the extr... more of the subtropical region of South America (i.e., the transition between the tropics and the extra tropics) in deciphering the forcing factors of past changes in atmospheric circulation. Both Argentinean and Uruguayan Holocene paleolimnological records indicate similar paleoclimatic trends, i.e. dominant dry conditions were observed during cold phases, whereas wet conditions prevailed during warm climatic phases. To our knowledge, this is the first attempt to integrate paleoclimatic data for the whole Pampean region. In addition, our results underscore the need to reinforce paleoclimate research at mid-latitudes in South America, in an attempt to fully appreciate natural climate variability beyond the instrumental record, as well as to design new strategies for the sustainable development of ecosystems and natural resources.
Although numerous studies concerning the Holocene climate of the southern Iberian Peninsula were ... more Although numerous studies concerning the Holocene climate of the southern Iberian Peninsula were accomplished within the last few decades, the climate history of this region is still poorly understood. Various studies deal with a combination of proxies, which are neither easy to compare nor is their connection easy to explain, e.g., due to spatial patterns and time transgression. Within this study, the suitability of the lacustrine sediments from the Laguna Salada (Andalucía region, southern Spain) as a paleoclimate archive is investigated. The lake sediments were evaluated using a multi-proxy approach including sedimentological, mineralogical, geochemical and biological analyses. The sediments reflect the evolution of the lake from pre-Medieval times onwards and Characeae as well as Ostracod analyses give an indication of paleosalinity. Moreover does the geochemical composition provide profound information concerning changes of elemental and mineralogical composition. Nevertheless, a robust, highresolution chronology could not be achieved owed to the scarcity of material available for radiocarbon dating and contamination problems. Furthermore, poor preservation of pollen restricted the reconstruction of vegetation history, which could have complemented important information concerning climatic changes and human activity.
Demographic estimates of hunter-gatherers during the Last Glacial Maximum in Europe against the b... more Demographic estimates of hunter-gatherers during the Last Glacial Maximum in Europe against the background of palaeoenvironmental data 1. Introduction This study aims to better understand population dynamics during the Last Glacial Maximum (LGM). In an interdisciplinary approach, it combines data from climatic modelling, geomorphology and archaeology. However, similar periods defined in archaeology and climatology are rarely exactly synchronous and the LGM is no exception. Following the EPILOG (Environmental Processes of the Ice-Age: Land, Oceans, Glaciers) project (cf. Mix et al., 2001), the LGM is defined as a period "reasonably close to an equilibrium state of climate" (Ibid., 629) comprising the maximum extent of global ice-shields and excluding short-term climatic extremes. Archaeologically, the LGM is associated with the Solutrean, Badegoulian, and Early Epigravettian (Djindjian et al., 1999). To strike a compromise between these conventions, the temporal boundaries of this study are set to 25,000 and 20,000 calBP. This allows for the integration of almost all sites assigned to the above-mentioned industries, while ensuring that the modelled palaeoclimate data can be considered representative of the period in question, since climatic conditions have been rather stable. It is important to stress that our estimates rely on the actual state of knowledge and the sites used in our calculations are considered a representative sample of all LGM sites known today. The distribution of sites in Figure 1 indicates that the settlement pattern during the LGM was spatially heterogeneous and clusters of sites alternate with empty areas. It is disputed whether this pattern reflects prehistoric reality or is mainly the result of taphonomic processes, research intensity and accessibility (e.g.
Lake Towuti (2.5°S, 121.5°E) is a longlived, tectonic lake located on the Island of Sulawesi, Ind... more Lake Towuti (2.5°S, 121.5°E) is a longlived, tectonic lake located on the Island of Sulawesi, Indonesia, and in the center of the Indo-Pacific warm pool (IPWP). Lake Towuti is connected with upstream lakes Matano and Mahalona through the Mahalona River, which constitutes the largest inlet to the lake. The Mahalona River Delta is prograding into Lake Towuti's deep northern basin thus exerting significant control on depositional processes in the basin. We combine high-resolution seismic reflection and sedimentological datasets from a 19.8-m-long sediment piston core from the distal edge of this delta to characterize fluctuations in deltaic sedimentation during the past *29 kyr BP and their relation to climatic change. Our datasets reveal that, in the present, sedimentation is strongly influenced by deposition of laterally transported sediments sourced from the Mahalona River Delta. Variations in the amount of laterally transported sediments, as expressed by coarse fraction amounts in pelagic muds and turbidite recurrence rates and cumulative thicknesses, are primarily a function of lake-level induced delta slope instability and delta progradation into the basin. We infer lowest lake-levels between *29 and 16, a gradual lake level rise between *16 and 11, and high lake-levels between *11 and 0 kyr BP. Periods of highest turbidite deposition, *26 to 24 and *18 to Electronic supplementary material The online version of this article (
Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording ... more Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording runoff from the Precordillera to the east, rather than local precipitation. Until now, paleoclimate records have not been reported from the hyperarid core of the Atacama Desert (<2 mm/yr). Here we report the results from multi-disciplinary investigation of a 6.2 m drill core retrieved from an endorheic basin within the Coastal Cordillera. The record spans the last 215 ka and indicates that the long-term hyperarid climate in the Central Atacama witnessed small but significant changes in precipitation since the penultimate interglacial. Somewhat ‘wetter’ climate with enhanced erosion and transport of material into the investigated basin, commenced during interglacial times (MIS 7, MIS 5), whereas during glacial times (MIS 6, MIS 4–1) sediment transport into the catchment was reduced or even absent. Pelagic diatom assemblages even suggest the existence of ephemeral lakes in the basin. Th...
Within the framework of the Baikal Drilling Project (BDP), a 192 m long sediment core (BDP-96-1) ... more Within the framework of the Baikal Drilling Project (BDP), a 192 m long sediment core (BDP-96-1) was recovered from the Academician Ridge, a submerged topographic high between the North and Central Basins of Lake Baikal. Sedimentological, clay mineralogical and geochemical investigations were carried out on the core interval between 90 and 124 m depth, corresponding to ca. 2.4-3.4 Ma. The aim was to reconstruct the climatic and tectonic history of the continental region during the intensification of Northern Hemisphere glaciation in Late Pliocene time. A major climate change occurred in the Lake Baikal area at about 2.65 Ma. Enhanced physical weathering in the catchment, mirrored in the illite to smectite ratio, and temporarily reduced bioproduction in the lake, reflected by the diatom abundance, evidence a change towards a colder and more arid climate, probably associated with an intensification of the Siberian High. In addition, the coincident onset of distinct fluctuations in these parameters and in the Zr/Al ratio suggests the beginning of the Late Cenozoic high amplitude climate cycles at about 2.65 Ma. Fluctuations in the Zr/Al ratio are traced back to changes in the aeolian input, with high values in warmer, more humid phases due to a weaker Siberian High. Assuming that the sand content in the sediment reflects tectonic pulses, the Lake Baikal area was tectonically active during the entire investigated period, but in particular around 2.65 Ma. Tectonic movements have likely led to a gradual catchment change since about 3.15 Ma from the western towards the eastern lake surroundings, as indicated in the geochemistry and clay mineralogy of the sediments. The strong coincidence between tectonic and climatic changes in the Baikal area hints at the Himalayan uplift being one of the triggers for the Northern Hemisphere Glaciation.
We present the reconstruction of the lake level fluctuation history from Lake El'gygytgyn located... more We present the reconstruction of the lake level fluctuation history from Lake El'gygytgyn located in central Chukotka, Russian Arctic. Lake El'gygytgyn was a subject of an international drilling project that resulted in recovering the longest paleoclimate and paleoenvironmental record of the terrestrial Arctic embracing the last 3.6 million years. Based on lithological and palynological studies and age determinations of shallow lake sediment cores and subaerial lake terraces, we have reconstructed lake level changes back to MIS 7. The reconstructed lake level history shows abrupt rising during glacial-interglacial transitions (MIS 6 to MIS 5 and MIS 2 to MIS 1) and smoother changes during the MIS 4 to MIS 3 stadial-interstadial transition. The most prominent low-level stands are reconstructed for glacial periods, which are associated with a permanent lake ice cover (i.e. MIS 6, 4 and 2). Late Glacial and Holocene lake level changes show a good correlation with changes in precipitation. Milankovic driven insolation changes likely control the permanent or seasonal character of the lake ice cover and is the main driving factor for the long-term level oscillations in the glacial-interglacial cycles. During periods of seasonal ice cover, the lake level fluctuations had the smaller amplitude depending mostly on changes in precipitation. Thus, Lake El'gygytgyn level changes are climate driven and sensitive to both precipitation and temperature.
INDONESIA AND IMPLICATIONS FOR MAFIC LACUSTRINE SEDIMENTS IN GALE CRATER, MARS. R. Y. Sheppard1*,... more INDONESIA AND IMPLICATIONS FOR MAFIC LACUSTRINE SEDIMENTS IN GALE CRATER, MARS. R. Y. Sheppard1*, R. E. Milliken1, J. M. Russell1, M. D. Dyar2,3, E. C. Sklute3, S. Bijaksana4, M. Melles5, and H. Vogel6. 1Dept. Earth, Environmental, and Planetary Sciences, Brown University, 2Dept. Astronomy, Mt. Holyoke College, 3Planetary Science Institute, 4Institut Teknologi Bandung, 5Institute of Geology and Mineralogy, University of Cologne, 6Institute of Geological Sciences & Oeschger Centre for Climate Change Research, University of Bern.
Deposition of ferruginous sediment was widespread during the Archaean and Proterozoic Eons, playi... more Deposition of ferruginous sediment was widespread during the Archaean and Proterozoic Eons, playing an important role in global biogeochemical cycling. Knowledge of organic matter mineralization in such sediment, however, remains mostly conceptual, as modern ferruginous analogs are largely unstudied. Here we show that in sediment of ferruginous Lake Towuti, Indonesia, methanogenesis dominates organic matter mineralization despite highly abundant reactive ferric iron phases like goethite that persist throughout the sediment. Ferric iron can thus be buried over geologic timescales even in the presence of labile organic carbon. Coexistence of ferric iron with millimolar concentrations of methane further demonstrates lack of iron-dependent methane oxidation. With negligible methane oxidation, methane diffuses from the sediment into overlying waters where it can be oxidized with oxygen or escape to the atmosphere. In low-oxygen ferruginous Archaean and Proterozoic oceans, therefore, sedi...
Iron is the most abundant redox‐sensitive element on the Earth's surface, and the oxidation s... more Iron is the most abundant redox‐sensitive element on the Earth's surface, and the oxidation state, mineral host, and crystallinity of Fe‐rich phases in sedimentary systems can record details of water‐rock interactions and environmental conditions. However, we lack a complete understanding of how these Fe‐rich materials are created, maintained, and oxidized or reduced in sedimentary environments, particularly those with mafic sources. The catchment of Lake Towuti, Indonesia, is known to contain a wide range of abundant crystalline Fe oxide, and the lake has a long sedimentary history. Here, we study a ∼100 m long drill core from the lake to understand patterns of sedimentation and how young iron‐rich sediments are affected by diagenesis through geologic time. We use visible/near infrared and Mössbauer spectroscopy, X‐ray diffraction, bulk chemistry measurements, and statistical cluster analysis to characterize the core sediment. We find that the core sediment can be divided into ...
of the subtropical region of South America (i.e., the transition between the tropics and the extr... more of the subtropical region of South America (i.e., the transition between the tropics and the extra tropics) in deciphering the forcing factors of past changes in atmospheric circulation. Both Argentinean and Uruguayan Holocene paleolimnological records indicate similar paleoclimatic trends, i.e. dominant dry conditions were observed during cold phases, whereas wet conditions prevailed during warm climatic phases. To our knowledge, this is the first attempt to integrate paleoclimatic data for the whole Pampean region. In addition, our results underscore the need to reinforce paleoclimate research at mid-latitudes in South America, in an attempt to fully appreciate natural climate variability beyond the instrumental record, as well as to design new strategies for the sustainable development of ecosystems and natural resources.
Although numerous studies concerning the Holocene climate of the southern Iberian Peninsula were ... more Although numerous studies concerning the Holocene climate of the southern Iberian Peninsula were accomplished within the last few decades, the climate history of this region is still poorly understood. Various studies deal with a combination of proxies, which are neither easy to compare nor is their connection easy to explain, e.g., due to spatial patterns and time transgression. Within this study, the suitability of the lacustrine sediments from the Laguna Salada (Andalucía region, southern Spain) as a paleoclimate archive is investigated. The lake sediments were evaluated using a multi-proxy approach including sedimentological, mineralogical, geochemical and biological analyses. The sediments reflect the evolution of the lake from pre-Medieval times onwards and Characeae as well as Ostracod analyses give an indication of paleosalinity. Moreover does the geochemical composition provide profound information concerning changes of elemental and mineralogical composition. Nevertheless, a robust, highresolution chronology could not be achieved owed to the scarcity of material available for radiocarbon dating and contamination problems. Furthermore, poor preservation of pollen restricted the reconstruction of vegetation history, which could have complemented important information concerning climatic changes and human activity.
Demographic estimates of hunter-gatherers during the Last Glacial Maximum in Europe against the b... more Demographic estimates of hunter-gatherers during the Last Glacial Maximum in Europe against the background of palaeoenvironmental data 1. Introduction This study aims to better understand population dynamics during the Last Glacial Maximum (LGM). In an interdisciplinary approach, it combines data from climatic modelling, geomorphology and archaeology. However, similar periods defined in archaeology and climatology are rarely exactly synchronous and the LGM is no exception. Following the EPILOG (Environmental Processes of the Ice-Age: Land, Oceans, Glaciers) project (cf. Mix et al., 2001), the LGM is defined as a period "reasonably close to an equilibrium state of climate" (Ibid., 629) comprising the maximum extent of global ice-shields and excluding short-term climatic extremes. Archaeologically, the LGM is associated with the Solutrean, Badegoulian, and Early Epigravettian (Djindjian et al., 1999). To strike a compromise between these conventions, the temporal boundaries of this study are set to 25,000 and 20,000 calBP. This allows for the integration of almost all sites assigned to the above-mentioned industries, while ensuring that the modelled palaeoclimate data can be considered representative of the period in question, since climatic conditions have been rather stable. It is important to stress that our estimates rely on the actual state of knowledge and the sites used in our calculations are considered a representative sample of all LGM sites known today. The distribution of sites in Figure 1 indicates that the settlement pattern during the LGM was spatially heterogeneous and clusters of sites alternate with empty areas. It is disputed whether this pattern reflects prehistoric reality or is mainly the result of taphonomic processes, research intensity and accessibility (e.g.
Lake Towuti (2.5°S, 121.5°E) is a longlived, tectonic lake located on the Island of Sulawesi, Ind... more Lake Towuti (2.5°S, 121.5°E) is a longlived, tectonic lake located on the Island of Sulawesi, Indonesia, and in the center of the Indo-Pacific warm pool (IPWP). Lake Towuti is connected with upstream lakes Matano and Mahalona through the Mahalona River, which constitutes the largest inlet to the lake. The Mahalona River Delta is prograding into Lake Towuti's deep northern basin thus exerting significant control on depositional processes in the basin. We combine high-resolution seismic reflection and sedimentological datasets from a 19.8-m-long sediment piston core from the distal edge of this delta to characterize fluctuations in deltaic sedimentation during the past *29 kyr BP and their relation to climatic change. Our datasets reveal that, in the present, sedimentation is strongly influenced by deposition of laterally transported sediments sourced from the Mahalona River Delta. Variations in the amount of laterally transported sediments, as expressed by coarse fraction amounts in pelagic muds and turbidite recurrence rates and cumulative thicknesses, are primarily a function of lake-level induced delta slope instability and delta progradation into the basin. We infer lowest lake-levels between *29 and 16, a gradual lake level rise between *16 and 11, and high lake-levels between *11 and 0 kyr BP. Periods of highest turbidite deposition, *26 to 24 and *18 to Electronic supplementary material The online version of this article (
Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording ... more Paleoclimate records from the Atacama Desert are rare and mostly discontinuous, mainly recording runoff from the Precordillera to the east, rather than local precipitation. Until now, paleoclimate records have not been reported from the hyperarid core of the Atacama Desert (<2 mm/yr). Here we report the results from multi-disciplinary investigation of a 6.2 m drill core retrieved from an endorheic basin within the Coastal Cordillera. The record spans the last 215 ka and indicates that the long-term hyperarid climate in the Central Atacama witnessed small but significant changes in precipitation since the penultimate interglacial. Somewhat ‘wetter’ climate with enhanced erosion and transport of material into the investigated basin, commenced during interglacial times (MIS 7, MIS 5), whereas during glacial times (MIS 6, MIS 4–1) sediment transport into the catchment was reduced or even absent. Pelagic diatom assemblages even suggest the existence of ephemeral lakes in the basin. Th...
Within the framework of the Baikal Drilling Project (BDP), a 192 m long sediment core (BDP-96-1) ... more Within the framework of the Baikal Drilling Project (BDP), a 192 m long sediment core (BDP-96-1) was recovered from the Academician Ridge, a submerged topographic high between the North and Central Basins of Lake Baikal. Sedimentological, clay mineralogical and geochemical investigations were carried out on the core interval between 90 and 124 m depth, corresponding to ca. 2.4-3.4 Ma. The aim was to reconstruct the climatic and tectonic history of the continental region during the intensification of Northern Hemisphere glaciation in Late Pliocene time. A major climate change occurred in the Lake Baikal area at about 2.65 Ma. Enhanced physical weathering in the catchment, mirrored in the illite to smectite ratio, and temporarily reduced bioproduction in the lake, reflected by the diatom abundance, evidence a change towards a colder and more arid climate, probably associated with an intensification of the Siberian High. In addition, the coincident onset of distinct fluctuations in these parameters and in the Zr/Al ratio suggests the beginning of the Late Cenozoic high amplitude climate cycles at about 2.65 Ma. Fluctuations in the Zr/Al ratio are traced back to changes in the aeolian input, with high values in warmer, more humid phases due to a weaker Siberian High. Assuming that the sand content in the sediment reflects tectonic pulses, the Lake Baikal area was tectonically active during the entire investigated period, but in particular around 2.65 Ma. Tectonic movements have likely led to a gradual catchment change since about 3.15 Ma from the western towards the eastern lake surroundings, as indicated in the geochemistry and clay mineralogy of the sediments. The strong coincidence between tectonic and climatic changes in the Baikal area hints at the Himalayan uplift being one of the triggers for the Northern Hemisphere Glaciation.
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