All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2.
Initial results of U.S.‐Soviet paleoclimate study of Lake Baikal
Eos, Transactions American Geophysical Union,
73
(43)
457 – 462
1992
ISSN: 00963941Keywords:▾
Russian Federation, Lake Baikal; age determination; dating; palaeoclimate; Pleistocene/Holocene boundary; sediment core; seismic reflection profile
Abstract: ▾ Lake Baikal, a Miocene‐age rift lake in southeastern Siberia, is an especially promising site for paleoclimate studies. Its high‐latitude location (52°–56°N) makes it particularly sensitive to changes in solar insolation due to long‐period variations in the Earth's orbital parameters. These variations are widely believed to be the main forcing functions of climate change in the Quaternary [Hays et al., 1976; Imbrie et al., 1984. The extreme continentality of the climate in southeastern Siberia makes Baikal an ideal location to study temporal changes in seasonality. Baikal is also one of the few high‐latitude lakes that has not been glaciated during the last 1–2 million years [Grosswald, 1980], although a record of glaciation in its drainage basin is preserved in the lake sediments. Finally, Lake Baikal is the largest (23,000 km3), the deepest (1640 m), and one of the oldest extant lake systems in the world. The sedimentary section in the Baikal depression is more than 7 km thick and probably spans more than 15 million years [Hutchinson et al., 1992]. Accordingly, Lake Baikal sediments represent one of the longest and most complete continental climate records available anywhere in the world. ©1992. American Geophysical Union. All Rights Reserved.
1.
Sedimentation in Lake Malawi (East Africa) during the past 10,000 years: a continuous paleoclimatic record from the southern tropics
Palaeogeography, Palaeoclimatology, Palaeoecology,
85
(3-4)
351-366
1991
ISSN: 00310182Keywords:▾
carbonate precipitation; chemocline depth; climate; climate trend; diatom; Holocene; lake level; micrite; palaeoclimate; palaeoclimate record; salinity; sedimentation, Malawi, Lake Malawi
Abstract: ▾ A suite of piston cores recovered from Lake Malawi (9-14°S, 34-35°E), east Africa in 1986 has been analyzed for major and minor elements, organic C and N, calcium carbonate and diatoms. An internally consistent stratigraphy was constructed from calcium carbonate abundance and variations in the two most abundant diatom genera, Stephanodiscus and Melosira, with age control obtained primarily from 14C dating of the carbonate. Differences with time in Fe abundance in a transect of cores from different water depths have been interpreted to reflect changes in chemocline depth. The depth to the chemocline was on the order of 100 m shallower than present prior to 3500 yr B.P., indicating less seasonality. Carbonate production and preservation appears to be related to climatically induced changes in both salinity and chemical distributions in the water column. The carbonate, which precipitates from surface waters, is most abundant during the interval from about 10,000 to 6000 yr B.P. This micrite most likely represents periods of low lake level when salinity increased and carbonate precipitation was enhanced. Sedimentary evidence suggests that lake levels were 100-150 m lower than present during this period. This record is different from climatic trends in northern intertropical Africa, but appears to also be related to changes in insolation and monsoon circulation. This is the northernmost basin in Africa reported to exhibit a "southern hemisphere" response to the early Holocene northern hemisphere summer insolation maximum. The climatic hingeline north of Lake Malawi (∼ 9°S) implied by our results is significantly south of that indicated by general-circulation model simulations, however. The cores show evidence for periods of abrupt climate change during the interval of generally arid climate. © 1991.