Detrital zircon U-Pb geochronology of the Xining loess in the northeastern Tibetan Plateau

Abstract

Based on age distributions of detrital zircon in different sedimentary layers of the Xining loess, we analyzed temporal provenance variations of the Xining loess and possible spatial variations between loess records in northeastern Tibetan Plateau and in the hinterland of the Chinese Loess Plateau (CLP). The results show that there are no obvious long-term temporal variations in provenance of the Xining loess since ∼1.3 Ma, although the relative contribution of detritus from the Central Asia Organic Belt (CAOB) and the Northern Tibetan Plateau may slightly vary through time. Comparison of the zircon U-Pb age spectra between the Xining loess and loess in the western-central CLP demonstrates that their sediment provenances are almost consistent except for the absence of <190 Ma zircon group in Xining, probably implying that the hinterland of the CLP may have received more eolian dust from the CAOB compared with the Xining areas. Our results corroborate the view that the northeastern Tibetan Plateau is one of the dominant suppliers of detrital materials to the CLP besides the CAOB.