QAIDAM_Pilot_15Ma -  Monsoon dynamics and aridification – the climate archive Qaidam

Lacustrine and, to a lesser extent, fluvial sediments in Cenozoic basins are the preferred archives for quantifying Central Asian paleoclimate and environmental change because of their widespread distribution and excellent potential for archiving, and monitoring.

 

Long-term, high-resolution, multi-parameter proxy records from the Tibetan Plateau (TP) and its surrounding mountain ranges and basins are a critical piece of evidence needed for reconstructing monsoon evolution. Lacustrine sediments are by far the most promising archive because of their relatively continuous and high-resolution record of events. However, at present there are no such suitable high-resolution data available that cover a major time span before and since the initiation of monsoonal climate. Work by Wang et al. (1999) ranges throughout the Cenozoic, including pollen data, but is of very low resolution. Other results from drill-cores in NE Tibet are longer and more continuous (one of them even dating back to 4.4 Ma), but these cores were primarily recovered for salt exploration and lack a detailed investigation of paleoclimate proxies (Shen et al. 1993; Liu et al. 1998).

The Qaidam Basin, a ~120,000 km2 large basin located at the NE Tibetan plateau has received significant attention as an important basin for hydrocarbon resources. The basin is surrounded by the Altyn Tagh and Qilian Shan mountain ranges, thus being also of interest for studying the formation of the TP. During the Eocene-Oligocene, the surrounding mountain ranges were uplifted probably as a result of the India-Asia collision, combined with largescale subsidence in the western basin where extensive deep lacustrine facies developed (e.g. Métivier et al. 1998; Sun et al. 2004). Folding and deformation in the western basin resulted in the migration of the depocenter to the eastern basin where the thickest sequence of Quaternary deep lacustrine mudstones was deposited (>10 km thickness). These mudstones are partially organic-rich and alternate with salt layers, making the sequence interesting for hydrocarbon and salt exploration and exploitation.

 

The objective of this project is the reconstruction of the long time paleo-environmental development at the NE margin of the Tibetan Plateau, especially for the time span in which the monsoon system has developed and the aridification of central Asia took place. This aim requires further drilling in the western Qaidam Basin. First, a pilot study is planned which helps to clearly define achievable objectives and shows possible alternative approaches. The interpretation will extensively evaluate existing and new data.

If the pilot study is successful, further drilling is planned with the aim to gain a continuous sequence of lacustrine sediments which is suitable with respect to availability of climate proxies for paleoclimate reconstruction. They should go back as far as possible towards an age range of 15 Ma.

 

Involved institutes and working groups

Eberhard Karls Universität Tübingen, Fachbereich Angewandte Geowissenschaften, AG Geophysik

Senckenberg Forschungsinstitut und Naturmuseum Frankfurt

Universität Frankfurt, Institut für Geowissenschaften, Paleo-environmental Dynamics Group