Supra-regional signal pathways and long-time archives: Quaternary monsoon dynamics at the northern margin of the Tibetan Plateau

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Veit Christian Nottebaum

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Summary

Sand Sea Gaxun Nur G. Stauch Sand sea in the Gaxun Nur basin

The project named „Supra-regional signal pathways and long-time archives: Quaternary monsoon dynamics at the northern margin of the Tibetan Plateau”, (in short: QuaSi) focuses on late quaternary climatic development using longtime and recent sediment archives. The team consists of scientists from RWTH Aachen University, the Alfred-Wegener-Institute (AWI) Potsdam, the Free University of Berlin and Chinese Partners from Nanjing University.

The endorheic Gaxun Nur Basin in northwestern China represents a sediment storage along a supra-regional sediment cascade. The catchment (~180.000 km2) comprises parts of southern Mongolia and reaches up to the northeastern margin of the Tibetan highlands (Qilian Shan Mountain Range). The basin itself is fully arid and provides high sediment amounts to the deflation for N-NW winds. The southeasterly bordering sand deserts (Badain Jaran and Tengger Shamo) as well as the Chinese Loess Plateau represent the direct sinks of the cascade. Furthermore, fine silty particles are transported via northern hemisphere’s westerly circulation downwind tot he North Pacific, North America and even Greenland.
A 230 m sediment core drilling comprises the sedimentologic history of the whole Quaternary in the basin and therefore represent a valuable long-time sediment archive. It was sampled in high resolution and analyzed for their geochemical, granulometric, mineralogical composition and its palaeomagnetic properties. Results allow a landscape reconstruction including conclusions about palaeoclimatic evolution of this climatically very sensitive area. Furthermore, this yields important information about the role of the Gaxun Nur Basin as an important dust source for loess accumulation on the Chinese Loess Plateau, relating these findings to central Asian monsoon variability. Additionally, granulometric, geochemical and mineralogical analyses from surface samples taken in the whole catchment allow extrapolation into the extent of the catchment. This yields important information on sediment provenance and transport mechanisms in relation to the variable geomorphological settings. The point data extracted from the drilling results can thus be expanded by another dimension. Hereafter, the results allow a deciphering of the sediment cascade in a resolution suitable to the vast extent of the catchment along the transition of Tibetan Highlands to northern Chinese deserts. It hence addresses the spatial and temporal variability of the central Asian monsoon system.

 
Duration 06/2011 - 05/2014
Funding BMBF, Prof. Dr. F. Lehmkuhl, Dr. G. Stauch
Project partners

Prof. Dr. Klaus Reicherter – Neotektonik und Georisiken, RWTH Aachen University

Prof. Dr. Bernhard Diekmann – Alfred-Wegener-Institut Potsdam

Dr. Kai Hartmann – Fachbereich Geowissenschaften, Freie Universität Berlin

Prof. Dr. Bernd Wünnemann – Nanjing University