Decoupling of the detrital linkage between proximal dunefields and early and middle Pleistocene accumulation in the Chinese Loess Plateau: evidence from the Badain Jaran and Tengger sandy deserts

Abstract

The dunefields upwind of the Chinese Loess Plateau (CLP) are widely regarded as the major source of the sediments of the CLP. To test this inference, we conducted a source tracing study using U–Pb age spectra of detrital zircons from the central Badain Jaran Desert (BJD). The results reveal that since 1.1 Ma the sediments in the central BJD have originated predominantly from the Gobi-Altay Mountains (GAMs), with a dominant Northern Tibetan Plateau (NTP) provenance at ∼0.7 Ma and at the present. Together with a previous study of the neighboring Tengger Desert (TD), our results support the conclusion that during 2.35–0.62 Ma the central parts of the proximal dunefields of the BJD and TD acted as reservoirs of sediments deflated mainly from strata with a GAMs-origin, with the addition of NTP-derived sediments after 0.36 Ma. Comparison of the original provenance areas of sediments in the central parts of the BJD and TD with the loess deposits in the central and southern CLP indicates that the proximal dunefields of the BJD and TD were not the dominant sources of dust transported to the CLP during early to middle Quaternary. Based on our results, combined with evidence from previous studies, we propose that NTP-derived sediments dominated accumulation in the CLP for most of the Quaternary, while during 2.35–0.62 Ma the proximal dunefields, including the BJD and TD, acted only as reservoirs of sediments deflated and eroded predominantly from the GAMs. Essentially, these sandy deserts functioned as transfer stations, which, after ∼0.36 Ma, received increased amounts of NTP-derived sediments and subsequently supplied silt to downwind areas, including the CLP.