Assessing the provenance of loess and desert sediments in northern China using U-Pb dating and morphology of detrital zircons

Thomas Stevens, Carl Palk, Andrew Carter, Huayu Lu, Peter D. Clift

Research output: Contribution to journalArticlepeer-review

Abstract

Chinese loess is regarded as one of the most detailed and long-term archives of climate on land. However, there is still significant controversy over the deposit's origin, limiting interpretation of the sedimentological and paleoclimatic mechanisms responsible for its emplacement. Here this is addressed through morphology and the first laser ablation–inductively coupled plasma–mass spectrometer (LA-ICP-MS) U-Pb ages of detrital zircons from loess (last glacial age; northern Loess Plateau). These are compared to zircon U-Pb age spectra from desert and sandy lands surrounding the Loess Plateau. Surface samples were taken from the Tengger and Mu Us deserts, as well as the Horqin and Otindag sandy lands. The results demonstrate that zircon U-Pb ages can discriminate between potential source areas and highlight both similarities and differences in age spectra for the desert and sandy land samples. Most significantly, the loess age spectrum shows no single affinity to any of these regions and exhibits zircon ages associated with granitoid rocks representing tectonic events in both west and east northern China. Furthermore, and in contrast to proximal deserts, a significant proportion of zircons from the loess show affinities with rocks cropping out in the Qilian Mountains. The euhedral form of many of these grains further suggests direct transport from these crystalline source rocks, in contrast to previously hypothesized production or storage in deserts. Thus, dust-transporting storms tracked from the west during the last glacial maximum, although this does not explain all the zircon variability and implies multiple sources and storm-track variation over the depositional period.
Original languageEnglish
Pages (from-to)1331-1344
Number of pages14
JournalGeological Society of America Bulletin
Volume122
Issue number7-8
Early online date29 Mar 2010
DOIs
Publication statusPublished - 2010

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