Rivers of dust - loess deposition and major rivers

Thomas Stevens1, Anna Bird1, Andrew Carter2, Pieter Vermeesch2, Timothy Watson1, Huayu Lu3, Sergio Andò4, Eduardo Garzanti4, Michael Cottam1, Inga Sevastjanova1, Martin Rittner2
1 Royal Holloway, University of London
2 Birkbeck, University of London
3 Nanjing University
4 Universita di Milano-Bicocca

V 2.2 in Löss und terrestrische Archive

17.09.2012, 16:30-16:50, H8

The origin of loess deposits worldwide is a source of considerable debated. The Chinese Loess Plateau contains one of the most valuable Cenozoic climate archives on land. Here, polarization of the debate over sediment sources is evident from a range of hypotheses that cover sediment sources in deserts, alluvial fans, mountain regions and Tibetan plateau. However, the question of the relationship of dust and sand sediment sources to the major river systems in the region has not previously be substantivey addresed.

This project uses single-grains of zircon for U-Pb and fission-track dating alongside heavy mineral analysis to test the role of proximal deserts and the potential influence of major rivers. Initial results suggest that the samples from the eastern Mu Us desert and the Tengger desert can be explained by local sources and recycling of the underlying Cretaceous rock. However, the western Mu Us desert samples show different zircon U-Pb age spectra and heavy mineral distributions, indicative of a strong influence from Tibet. Further, samples from the Yellow River are close to identical to these western Mu Us samples and, crucially, to samples from the Loess Plateau. This and the differences between samples from the Tengger desert, the Loess Plateau, the western Mu Us and the eastern Mu Us suggests that the Tibetan sediments are unlikely to have been transported directly by wind, but rather have been delivered by the Yellow River. This provides the first evidence of a genetic link between the Yellow River and the Loess Plateau.

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Letzte Änderung 31.07.2012