Dating of Middle Pleistocene sediments from a large freshwater lake in the Qaidam Basin, NW China to reveal the climatic and environmental differences to the conditions of the last 30 ka
Final Report Abstract
A large freshwater to oligohaline lake in the Qaidam Basin is inferred from ostracod assemblages and grain-size data of a 50 m thick sediment sequence. OSL and 230Th/U ages indicate a middle Pleistocene age sometime between 120 and 400 kyr, although we were not able to establish a detailed chronology for the section. Our dating results do not support a speculative relationship between the middle Pleistocene global climate history and the formation of the reconstructed large freshwater to oligohaline lake in the Qaidam Basin, however, the scenario of a pronounced long-term snow accumulation in the surrounding mountain ranges during MIS 10 (~340 kyr) and the rapid supply of large meltwater quantities during Termination IV provides a possible explanation for the sources of the required water quantities to fill a depression of the size of the Qaidam Basin as has been inferred as a result of this study. It was not possible to establish a firm chronology of the sampled section although two previously performed 230Th/U age determinations provided promising results. However, the newly obtained data could be used to assign the formation of the sediments to a period sometime in the middle Pleistocene and could therefore enlarge our knowledge concerning the timing of the formation of a large freshwater lake in the Qaidam Basin to some degree. Minimum ages of about 130 ka and a single 230Th/U age of about 200 ka had been available before we conducted our attempt to establish the chronology of the section. Results of the project were already presented during the „Lange Nacht der Wissenschaften“ („Long Night of the Sciences“) at the Freie Universitaet Berlin in June, 2007. Additional public-media activities with respect to the project are not expected.
Publications
- 2006: A large Middle Pleistocene freshwater lake in a presently dry Tibetan Basin. Terra Nostra, Abstract-Volume GV International Conference: 74
Mischke, S., Herzschuh, U., Sun, N., Qiao, Z., Sun, Z.
- 2006: Opening up a unique high-resolution climate archive of the last 1.3Ma from the Qaidam Basin, China. IODP-ICDP Kolloquium 2006 in Greifswald. Abstract Volume: 93-94
Mischke, S.
- 2007: An ostracod-inferred large Pleistocene freshwater lake in the presently hyper-arid Qaidam Basin (NW China). XVII INQUA Congress, The tropics: heat engine of the Quaternary. Quaternary International, 167-168 Suppl., 284
Mischke, S., Herzschuh, U., Qiao, Z., Sun, N., Sun, Z.
