- Email: [email protected]
MIS3 14C reservoir ages changes inferred from the LINK15 sediment core, Faroe-Shetland channel, North Atlantic
Abstracts / Quaternary International 279-280 (2012) 346–461
about 30% of the Holocene melting of the Antarctic ice sheet on the basis of RSL variations distant from the glaciated region at the LGM described by previous authors. PALAEOECOLOGICAL EVOLUTION IN SIERRA NEVADA (SOUTHERN SPAIN) OVER THE LAST MILLENNIUM INFERRED FROM SOLIFLUCTION LANDFORMS, LAKE SEDIMENTS AND DOCUMENTARY SOURCES Marc Oliva. University of Lisbon, Portugal
359
controversy. The investigated closed depressions were still visible in the landscape and situated on Triassic marls and clays (Keuper). The weak geomorphological interest to deformations affecting this gypsum-rich geological formation may explain why an anthropogenic explanation was still preferred until now. The recent research focused on the realisation of long and deep trenches, which allowed direct geomorphological observations and the 3D documentation of the formation processes and the sedimentary history of these closed depressions. This study allows the understanding of processes such as:
E-mail address: [email protected]
Our research area is located in the climate-sensitive present-day periglacial belt of Sierra Nevada (Southern Spain), at elevations ranging from 2500 to 3000 m asl. We have reconstructed landscape changes and phases of geomorphic activity in this massif over the last millennia focusing on two different sedimentary archives: mountain lakes and solifluction lobes. Sedimentological studies of both records suggest that cold and wet phases were propitious for slope processes whereas slope stability and soil formation prevailed during (dry and wet) warm periods. Historical documents also provide palaeoenvironmental information of the highest parts of the massif for the last millennium. We have contrasted data from sedimentary archives and documentary sources. During the Medieval Warm Period soil formation was dominant, slope processes showed a weak activity and no glacier existed in the Corral del Veleta cirque. Cold and wet phases during the Little Ice Age favoured the development of small glaciers in the northern cirques and promoted enhanced geomorphic activity in Sierra Nevada. Finally, the warming trend of the last 150 years has melted the southernmost European glaciers and reduced the activity of contemporary geomorphic processes in this semiarid massif.
(1) the initiation of closed depressions by small Quaternary faulting affecting the Triassic marls, (2) the deepening of closed depressions by alteration of superficial marls and residual clays passage down existing faults, (3) the filling-up of these sediment traps and the formation of humid zones established in the depressions after the end of subrosional processes, (4) the modifications of the shape of the closed depression’s edges, due to degradation of marl blocks, which was possibly caused by the circulation of precipitation waters trough microcracks. (5) the recording of sedimentary and vegetation history showing land use and human settlement dynamics since the Iron Age. MEDIEVAL FLOOD RISK OF THE LIZAINE RIVER IN THE TOWN OF MONTBELIARD (DOUBS, FRANCE) DECIPHERED FROM SEDIMENTARY AND HISTORICAL RECORDS Vincent Ollive. Institut national de recherches archéologiques, France E-mail address: [email protected]
PRELIMINARY RESULTS OF THE HOLOCENE PALAEOENVIRONMENTAL EVOLUTION IN THE SERRA DA ESTRELA (PORTUGAL) Marc Oliva. University of Lisbon, Portugal E-mail address: [email protected]
The Serra da Estrela constitutes the westernmost high massif of the Iberian Central Cordillera and the highest mountainous area in Portugal, reaching moderate elevations of only 1993 m asl at the summit of Torre plateau. This granite massif presents different plateau surfaces and deeply incised valleys shaped by the Last Glacial Maximum. Previous geomorphological and sedimentological studies have shown evidences of an extensively glaciated area during the period of the maximum glacier extent although there are still major uncertainties about the chronology of the deglaciation. By analyzing the sediments filling glacial depressions we may reconstruct the environmental evolution in the highest parts of the massif since their deglaciation. In this sense, we have sampled a wetland area in a plateau located in between a complex moraine system at an elevation of 1500 m asl (Nave de San António). We have collected several short cores (2-3 m depth) and analyzed their geochemical and sedimentological properties. According to the first datings performed in our key profile, the upper infill of these depressions is much younger than expected, revealing significant environmental changes during the Late Holocene in the massif. However, landscape evolution in this area may be a consequence both from climate variability and human activity, which may have also disturbed the uppermost sediments. FORMATION PROCESSES AND SEDIMENTARY FILLING HISTORY OF CLOSED DEPRESSIONS ON THE PLATEAU LORRAIN, NORTH-EASTERN PARIS BASIN (FRANCE) Vincent Ollive. Institut national de recherches archéologiques, France E-mail address: [email protected]
The anthropogenic or geological origin of closed sub-circular depressions (mardelles) on the ‘plateau lorrain’, north-eastern part of Paris basin is highly debated since the second half of the 19th century. During rescue excavations along the high speed train line ‘LGV-Est Européenne’ in 2010 several of these closed sub-circular depressions were investigated by a pluridisciplinary Inrap research team to resolve this
Geoarchaeological investigations were carried out during rescue archaeological excavations in the medieval urban area of Montbeliard. At the begining of 14th centuries, a new district of the town, a covered marketplace, was built in a lateral part of the Lizaine River alluvial plain. During this period, two floods occurred as attested by their deposits recorded which were studied by sedimentology, and dated by archaeological and dendrochronological methods. The first was found interlayered with anthropogenic layers that attest the destruction of the marketplace building after few decades of existence and before 1480 AD after dendrological dating. A new building was built immediately after this hydrological event. The second event occurred between 1503 AD and 1535 AD after dendrological dating, period of edification of the modern marketplace building. These events inform us on medieval hydrological risk in the urban area of Montbéliard and extend the reconstructed Lizaine documentary flood serie limited to the 16th-19th centuries. MIS3 14C RESERVOIR AGES CHANGES INFERRED FROM THE LINK15 SEDIMENT CORE, FAROE-SHETLAND CHANNEL, NORTH ATLANTIC Jesper Olsen. Queen’s University Belfast, United Kingdom E-mail address: [email protected]
In ice cores the last glacial period is characterised by millennial-scale Dansgaard-Oeschger (D-O) events of warmer and colder climates. Similar millennial-scale variability (linked to D-O events) is evident from oceanic cores suggesting a strong coupling of the atmospheric and oceanic circulations system. Cooling and sinking of dense saline water originating from the North Atlantic Drift current in the Norwegian-Greenland Sea is essential for the formation of North Atlantic Deep Water. The convection in the Norwegian-Greenland Sea allows for a northward heat exchange and southward transport of cold saline water. This circulation system is highly sensitive to climate change and has been shown to operate in different modes. The different oceanic circulation modes further have a large influence on the carbon exchange between atmosphere and the deep ocean. Such reorganisations of the North Atlantic circulations system and deep water formation cause changes in the 14C activity of the surface ocean. Here we
360
Abstracts / Quaternary International 279-280 (2012) 346–461
present 76 new AMS14C dates of planktonic foraminifera covering Marine Isotope Stage 3 from the LINK15 core taken from the Faroe-Shetland channel. The Faroe-Shetland channel is situated in the main path of the warm North Atlantic Drift current and further provides an escape route for the cold Norwegian Sea Deep Water. Hence LINK15 has an ideal position for studying paleo variability of 14C reservoir ages. Based on N. Pachyderma d18O, magnetic susceptibility and IRD the LINK15 sediment core has been correlated to the NGRIP ice core (GICC05 age scale). The correlated GICC05 ages of the LINK15 sediment core are then used to calculate marine reservoir ages (DR) using the marine radiocarbon calibration curve (Marine09). Our results show significant DR variability through the course of 6 D-O events. MAJORCA CAVES, SEA-LEVEL CHANGES, AND ASTRONOMICAL FORCING Bogdan P. Onac. Department of Geology, University of South Florida, United States E-mail address: [email protected]
The littoral caves of Mallorca have formed by the mixing of freshwater and seawater in the coastal phreatic zone, and are highly decorated with speleothems that formed during Quaternary time when the caves were airfilled chambers. Throughout the middle and upper Pleistocene, the caves were repeatedly flooded by glacio-eustatic sea level oscillations. The water level of each flooding event was recorded by a distinct encrustation (also known as phreatic overgrowths on speleothems, POS) of calcite or aragonite over existing speleothems and along cave walls. We have identified several well-defined encrustation horizons below and above the present-day sea level corresponding to older sea level events. Sea level chronologies based on POS that formed at the water table avoid at least three of the major problems encountered when reconstructing past sea level using corals: 1) assumptions about the water depth above the reef, 2) questions concerning the provenance of corals, and 3) uncertainties regarding the relationship between sea level position and the timing of coral reef or terrace formation. The carbonate encrustation mechanism allows for sub-meter sea level precision of documenting past sea levels. Using high-precision U/Th ages on the Mallorcan POS, we pinpoint western Mediterranean sea level at w1 m above modern at w81 ka during marine isotope stage (MIS) 5a. Dates of 116 and 121 ka (MIS 5e) on encrustations from the same cave at an elevation of 2.6 m imply that the w1 m highstand during MIS 5a primarily represents eustatic ice equivalent sea level, and has been negligibly affected by tectonic and isostatic effects. Our findings corroborate the minority view that MIS 5a was at least as ice-free as present. If, indeed, sea level was higher than present at 81 ka as our data suggests, the apparent 100 ka ice-age cycle seen to dominate the last 700 ka in deep sea sediments may not apply so directly to the growth and decay of the Quaternary ice sheets. MIDDLE STONE AGE EXPOSURES AT MORICHO, NEAR KILOMBE, KENYA Isaya Onjala. National Museums of Kenya, Kenya E-mail address: [email protected]
The extinct early Pleistocene volcano of Kilombe, Kenya, is the focus of several suites of sediments. At Moricho 2km NW of the main Kilombe Acheulean site, Middle and Upper Pleistocene sediments are found extending in a series of spectacular amphitheatre-like exposures. In initial exploration these have yielded MSA (Middle Stone Age) points on the surface, of both obsidian and lava; and also occasional flakes in situ, again including finds of lava as well as obsidian. The sediments are largely ‘red beds’, composed of thin tuffs and interposed weathering products, deriving in part from the slopes of the Kilombe volcano. In one case artefacts have been found between tuffs separated by as little as 60 cm, offering the prospect of studying assemblages with high stratigraphic resolution. At the base of the Moricho sequence a thick tuff resembles the ashflow tuff capping the Acheulean site exposures. A similar massive tuff also occurs within the caldera or crater of the Kilombe volcano, there overlying a series of lacustrine sediments. The poster gives details of stratigraphy, artefacts and sediment sampling.
OBSIDIAN EXPLOITAION AND PALAEOECOLOGY OF THE JAPANESE ISLANDS DURING MIS3 AND MIS2 Akira Ono. Meiji University, Japan E-mail address: [email protected]
Explicit evidence of human occupation that has based both on stratigraphy and morpho-typology of lithic artifacts is possible to trace back to the middle of MIS3 in the Japanese islands. The presentation focuses on obsidian exploitation patterns in the Kozu island, and the Mattobara Upper Palaeolithic site on the mountainous river terrace, with reference to the climatic changes during 70ka – 10ka from the boring data of the Lake Nojiri, Central North Japan. Generally, lithic assemblages continue from uppermost Palaeolithic Layer down to the Layer X in Kanto area, but a single artifact is available beneath the Layer X. This suggests the first peopling of the Japanese islands connected with this time period, ca. 38000 cal BP. The earliest evidence of obsidian procurement from Kozu island, was recognized in the Layer VII (Black band) of Ashitaka area dated as ca. 38000 cal BP. No land bridge was formed between Izu islands and Honshu, and also between Korean peninsula and Japanese islands even in the LGM. This implies a possibility of human migration from Asian mainland to the Japanese islands across the seawater in the middle of MIS3. Obsidian raw material exploitation strategy in the Upper Palaeolithic has been modeled in various ways. First, long distance direct procurement; second, indirect procurement through exchange network systems; and third, the raw material is programmed in the year-round scheduled socalled as an embedded strategy. Even though no single integrated explanatory model may applicable, raw material exploitation strategies are reflecting the different environmental settings of mountainous and isolated islands. POSTGLACIAL DETRITAL SEDIMENT SOURCES AND TRANSPORT PROCESSES IN LAKE DONGGI CONA, NORTHEASTERN TIBETAN PLATEAU, REVEALED BY MULTIVARIANTE STATISTICAL ENDMEMBERMODELLING (EMMA) OF SEDIMENTOLOGICAL DATA Stephan Opitz. Alfred Wegener Institute for Polar and Marine Rese, Germany E-mail address: [email protected]
Donggi Cona is a 95 m deep fresh-water lake, situated on the north-eastern Tibetan Plateau at an elevation of 4090 m a.s. The intramontane lake basin is part of several pull-apart structures associated with the east west oriented Kunlun Fault. The region is influenced by monsoonal air-mass systems of different origin, highly variable in space and time. The main objective of our joint Chinese-German research is the reconstruction of palaeoenvironmental changes of Lake Donggi Cona and its catchment area during the last 18-20 kyr. Here we report on the temporal variability of detrital sediment fluxes to the lake, as recorded in five up to 6.4 m long sediment cores, retrieved from water depths between 40 and 2 metres. To understand climate-related processes in the lake system, it is necessary to recognize the different sediment sources and modes of sedimentary transport into the lake. The study builds on a multi-proxy approach, using grain size, XRF, XRD, CNS and TOC data. With an end-member modelling algorithm (EMMA), based on principal component analyses and factor analyses, we separate (“unmix”) the multimodal distributed grain-size classes into several unimodal-process-classes. Empirical end-members are derived and compared to natural end-members, i.e. terrestrial surface samples from locations dominated by a single geomorphological process regime or sediment source. We present the results of this “unmixing” approach in relation to the interpretation of the sedimentological, mineralogical and geochemical findings of Lake Donggi Cona. HOLOCENE MANGROVE DYNAMICS AND ENVIRONMENTAL CHANGES IN THE COASTAL REGION OF SOUTH WESTERN NIGERIA Emuobosa Akpo Orijemie. University of Ibadan, Nigeria E-mail address: [email protected]
An 8m-core drilled in Ikorigho in the coastal region of South-Western Nigeria, has provided evidence of Holocene mangrove dynamics and
about 30% of the Holocene melting of the Antarctic ice sheet on the basis of RSL variations distant from the glaciated region at the LGM described by previous authors. PALAEOECOLOGICAL EVOLUTION IN SIERRA NEVADA (SOUTHERN SPAIN) OVER THE LAST MILLENNIUM INFERRED FROM SOLIFLUCTION LANDFORMS, LAKE SEDIMENTS AND DOCUMENTARY SOURCES Marc Oliva. University of Lisbon, Portugal
359
controversy. The investigated closed depressions were still visible in the landscape and situated on Triassic marls and clays (Keuper). The weak geomorphological interest to deformations affecting this gypsum-rich geological formation may explain why an anthropogenic explanation was still preferred until now. The recent research focused on the realisation of long and deep trenches, which allowed direct geomorphological observations and the 3D documentation of the formation processes and the sedimentary history of these closed depressions. This study allows the understanding of processes such as:
E-mail address: [email protected]
Our research area is located in the climate-sensitive present-day periglacial belt of Sierra Nevada (Southern Spain), at elevations ranging from 2500 to 3000 m asl. We have reconstructed landscape changes and phases of geomorphic activity in this massif over the last millennia focusing on two different sedimentary archives: mountain lakes and solifluction lobes. Sedimentological studies of both records suggest that cold and wet phases were propitious for slope processes whereas slope stability and soil formation prevailed during (dry and wet) warm periods. Historical documents also provide palaeoenvironmental information of the highest parts of the massif for the last millennium. We have contrasted data from sedimentary archives and documentary sources. During the Medieval Warm Period soil formation was dominant, slope processes showed a weak activity and no glacier existed in the Corral del Veleta cirque. Cold and wet phases during the Little Ice Age favoured the development of small glaciers in the northern cirques and promoted enhanced geomorphic activity in Sierra Nevada. Finally, the warming trend of the last 150 years has melted the southernmost European glaciers and reduced the activity of contemporary geomorphic processes in this semiarid massif.
(1) the initiation of closed depressions by small Quaternary faulting affecting the Triassic marls, (2) the deepening of closed depressions by alteration of superficial marls and residual clays passage down existing faults, (3) the filling-up of these sediment traps and the formation of humid zones established in the depressions after the end of subrosional processes, (4) the modifications of the shape of the closed depression’s edges, due to degradation of marl blocks, which was possibly caused by the circulation of precipitation waters trough microcracks. (5) the recording of sedimentary and vegetation history showing land use and human settlement dynamics since the Iron Age. MEDIEVAL FLOOD RISK OF THE LIZAINE RIVER IN THE TOWN OF MONTBELIARD (DOUBS, FRANCE) DECIPHERED FROM SEDIMENTARY AND HISTORICAL RECORDS Vincent Ollive. Institut national de recherches archéologiques, France E-mail address: [email protected]
PRELIMINARY RESULTS OF THE HOLOCENE PALAEOENVIRONMENTAL EVOLUTION IN THE SERRA DA ESTRELA (PORTUGAL) Marc Oliva. University of Lisbon, Portugal E-mail address: [email protected]
The Serra da Estrela constitutes the westernmost high massif of the Iberian Central Cordillera and the highest mountainous area in Portugal, reaching moderate elevations of only 1993 m asl at the summit of Torre plateau. This granite massif presents different plateau surfaces and deeply incised valleys shaped by the Last Glacial Maximum. Previous geomorphological and sedimentological studies have shown evidences of an extensively glaciated area during the period of the maximum glacier extent although there are still major uncertainties about the chronology of the deglaciation. By analyzing the sediments filling glacial depressions we may reconstruct the environmental evolution in the highest parts of the massif since their deglaciation. In this sense, we have sampled a wetland area in a plateau located in between a complex moraine system at an elevation of 1500 m asl (Nave de San António). We have collected several short cores (2-3 m depth) and analyzed their geochemical and sedimentological properties. According to the first datings performed in our key profile, the upper infill of these depressions is much younger than expected, revealing significant environmental changes during the Late Holocene in the massif. However, landscape evolution in this area may be a consequence both from climate variability and human activity, which may have also disturbed the uppermost sediments. FORMATION PROCESSES AND SEDIMENTARY FILLING HISTORY OF CLOSED DEPRESSIONS ON THE PLATEAU LORRAIN, NORTH-EASTERN PARIS BASIN (FRANCE) Vincent Ollive. Institut national de recherches archéologiques, France E-mail address: [email protected]
The anthropogenic or geological origin of closed sub-circular depressions (mardelles) on the ‘plateau lorrain’, north-eastern part of Paris basin is highly debated since the second half of the 19th century. During rescue excavations along the high speed train line ‘LGV-Est Européenne’ in 2010 several of these closed sub-circular depressions were investigated by a pluridisciplinary Inrap research team to resolve this
Geoarchaeological investigations were carried out during rescue archaeological excavations in the medieval urban area of Montbeliard. At the begining of 14th centuries, a new district of the town, a covered marketplace, was built in a lateral part of the Lizaine River alluvial plain. During this period, two floods occurred as attested by their deposits recorded which were studied by sedimentology, and dated by archaeological and dendrochronological methods. The first was found interlayered with anthropogenic layers that attest the destruction of the marketplace building after few decades of existence and before 1480 AD after dendrological dating. A new building was built immediately after this hydrological event. The second event occurred between 1503 AD and 1535 AD after dendrological dating, period of edification of the modern marketplace building. These events inform us on medieval hydrological risk in the urban area of Montbéliard and extend the reconstructed Lizaine documentary flood serie limited to the 16th-19th centuries. MIS3 14C RESERVOIR AGES CHANGES INFERRED FROM THE LINK15 SEDIMENT CORE, FAROE-SHETLAND CHANNEL, NORTH ATLANTIC Jesper Olsen. Queen’s University Belfast, United Kingdom E-mail address: [email protected]
In ice cores the last glacial period is characterised by millennial-scale Dansgaard-Oeschger (D-O) events of warmer and colder climates. Similar millennial-scale variability (linked to D-O events) is evident from oceanic cores suggesting a strong coupling of the atmospheric and oceanic circulations system. Cooling and sinking of dense saline water originating from the North Atlantic Drift current in the Norwegian-Greenland Sea is essential for the formation of North Atlantic Deep Water. The convection in the Norwegian-Greenland Sea allows for a northward heat exchange and southward transport of cold saline water. This circulation system is highly sensitive to climate change and has been shown to operate in different modes. The different oceanic circulation modes further have a large influence on the carbon exchange between atmosphere and the deep ocean. Such reorganisations of the North Atlantic circulations system and deep water formation cause changes in the 14C activity of the surface ocean. Here we
360
Abstracts / Quaternary International 279-280 (2012) 346–461
present 76 new AMS14C dates of planktonic foraminifera covering Marine Isotope Stage 3 from the LINK15 core taken from the Faroe-Shetland channel. The Faroe-Shetland channel is situated in the main path of the warm North Atlantic Drift current and further provides an escape route for the cold Norwegian Sea Deep Water. Hence LINK15 has an ideal position for studying paleo variability of 14C reservoir ages. Based on N. Pachyderma d18O, magnetic susceptibility and IRD the LINK15 sediment core has been correlated to the NGRIP ice core (GICC05 age scale). The correlated GICC05 ages of the LINK15 sediment core are then used to calculate marine reservoir ages (DR) using the marine radiocarbon calibration curve (Marine09). Our results show significant DR variability through the course of 6 D-O events. MAJORCA CAVES, SEA-LEVEL CHANGES, AND ASTRONOMICAL FORCING Bogdan P. Onac. Department of Geology, University of South Florida, United States E-mail address: [email protected]
The littoral caves of Mallorca have formed by the mixing of freshwater and seawater in the coastal phreatic zone, and are highly decorated with speleothems that formed during Quaternary time when the caves were airfilled chambers. Throughout the middle and upper Pleistocene, the caves were repeatedly flooded by glacio-eustatic sea level oscillations. The water level of each flooding event was recorded by a distinct encrustation (also known as phreatic overgrowths on speleothems, POS) of calcite or aragonite over existing speleothems and along cave walls. We have identified several well-defined encrustation horizons below and above the present-day sea level corresponding to older sea level events. Sea level chronologies based on POS that formed at the water table avoid at least three of the major problems encountered when reconstructing past sea level using corals: 1) assumptions about the water depth above the reef, 2) questions concerning the provenance of corals, and 3) uncertainties regarding the relationship between sea level position and the timing of coral reef or terrace formation. The carbonate encrustation mechanism allows for sub-meter sea level precision of documenting past sea levels. Using high-precision U/Th ages on the Mallorcan POS, we pinpoint western Mediterranean sea level at w1 m above modern at w81 ka during marine isotope stage (MIS) 5a. Dates of 116 and 121 ka (MIS 5e) on encrustations from the same cave at an elevation of 2.6 m imply that the w1 m highstand during MIS 5a primarily represents eustatic ice equivalent sea level, and has been negligibly affected by tectonic and isostatic effects. Our findings corroborate the minority view that MIS 5a was at least as ice-free as present. If, indeed, sea level was higher than present at 81 ka as our data suggests, the apparent 100 ka ice-age cycle seen to dominate the last 700 ka in deep sea sediments may not apply so directly to the growth and decay of the Quaternary ice sheets. MIDDLE STONE AGE EXPOSURES AT MORICHO, NEAR KILOMBE, KENYA Isaya Onjala. National Museums of Kenya, Kenya E-mail address: [email protected]
The extinct early Pleistocene volcano of Kilombe, Kenya, is the focus of several suites of sediments. At Moricho 2km NW of the main Kilombe Acheulean site, Middle and Upper Pleistocene sediments are found extending in a series of spectacular amphitheatre-like exposures. In initial exploration these have yielded MSA (Middle Stone Age) points on the surface, of both obsidian and lava; and also occasional flakes in situ, again including finds of lava as well as obsidian. The sediments are largely ‘red beds’, composed of thin tuffs and interposed weathering products, deriving in part from the slopes of the Kilombe volcano. In one case artefacts have been found between tuffs separated by as little as 60 cm, offering the prospect of studying assemblages with high stratigraphic resolution. At the base of the Moricho sequence a thick tuff resembles the ashflow tuff capping the Acheulean site exposures. A similar massive tuff also occurs within the caldera or crater of the Kilombe volcano, there overlying a series of lacustrine sediments. The poster gives details of stratigraphy, artefacts and sediment sampling.
OBSIDIAN EXPLOITAION AND PALAEOECOLOGY OF THE JAPANESE ISLANDS DURING MIS3 AND MIS2 Akira Ono. Meiji University, Japan E-mail address: [email protected]
Explicit evidence of human occupation that has based both on stratigraphy and morpho-typology of lithic artifacts is possible to trace back to the middle of MIS3 in the Japanese islands. The presentation focuses on obsidian exploitation patterns in the Kozu island, and the Mattobara Upper Palaeolithic site on the mountainous river terrace, with reference to the climatic changes during 70ka – 10ka from the boring data of the Lake Nojiri, Central North Japan. Generally, lithic assemblages continue from uppermost Palaeolithic Layer down to the Layer X in Kanto area, but a single artifact is available beneath the Layer X. This suggests the first peopling of the Japanese islands connected with this time period, ca. 38000 cal BP. The earliest evidence of obsidian procurement from Kozu island, was recognized in the Layer VII (Black band) of Ashitaka area dated as ca. 38000 cal BP. No land bridge was formed between Izu islands and Honshu, and also between Korean peninsula and Japanese islands even in the LGM. This implies a possibility of human migration from Asian mainland to the Japanese islands across the seawater in the middle of MIS3. Obsidian raw material exploitation strategy in the Upper Palaeolithic has been modeled in various ways. First, long distance direct procurement; second, indirect procurement through exchange network systems; and third, the raw material is programmed in the year-round scheduled socalled as an embedded strategy. Even though no single integrated explanatory model may applicable, raw material exploitation strategies are reflecting the different environmental settings of mountainous and isolated islands. POSTGLACIAL DETRITAL SEDIMENT SOURCES AND TRANSPORT PROCESSES IN LAKE DONGGI CONA, NORTHEASTERN TIBETAN PLATEAU, REVEALED BY MULTIVARIANTE STATISTICAL ENDMEMBERMODELLING (EMMA) OF SEDIMENTOLOGICAL DATA Stephan Opitz. Alfred Wegener Institute for Polar and Marine Rese, Germany E-mail address: [email protected]
Donggi Cona is a 95 m deep fresh-water lake, situated on the north-eastern Tibetan Plateau at an elevation of 4090 m a.s. The intramontane lake basin is part of several pull-apart structures associated with the east west oriented Kunlun Fault. The region is influenced by monsoonal air-mass systems of different origin, highly variable in space and time. The main objective of our joint Chinese-German research is the reconstruction of palaeoenvironmental changes of Lake Donggi Cona and its catchment area during the last 18-20 kyr. Here we report on the temporal variability of detrital sediment fluxes to the lake, as recorded in five up to 6.4 m long sediment cores, retrieved from water depths between 40 and 2 metres. To understand climate-related processes in the lake system, it is necessary to recognize the different sediment sources and modes of sedimentary transport into the lake. The study builds on a multi-proxy approach, using grain size, XRF, XRD, CNS and TOC data. With an end-member modelling algorithm (EMMA), based on principal component analyses and factor analyses, we separate (“unmix”) the multimodal distributed grain-size classes into several unimodal-process-classes. Empirical end-members are derived and compared to natural end-members, i.e. terrestrial surface samples from locations dominated by a single geomorphological process regime or sediment source. We present the results of this “unmixing” approach in relation to the interpretation of the sedimentological, mineralogical and geochemical findings of Lake Donggi Cona. HOLOCENE MANGROVE DYNAMICS AND ENVIRONMENTAL CHANGES IN THE COASTAL REGION OF SOUTH WESTERN NIGERIA Emuobosa Akpo Orijemie. University of Ibadan, Nigeria E-mail address: [email protected]
An 8m-core drilled in Ikorigho in the coastal region of South-Western Nigeria, has provided evidence of Holocene mangrove dynamics and