Identification of a late Quaternary alluvial-aeolian sedimentary sequence in the Sichuan Basin, China

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• 作者：Jin-Liang Feng^a ; ^{fengjl@itpcas.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Jian-Ting Ju^a ; Feng Chen^a ; ^b ; Zhao-Guo Hu^a ; ^c ; Xiang Zhao^d ; Shao-Peng Gao^a
• 关键词：Sichuan Basin ; Tibetan Plateau ; Alluvial sediment ; Aeolian deposit ; Compositional maturity ; Isotopic tracing ; Dust provenance ; Pedogenic concretions ; Sedimentary hiatus ; Strata age
• 刊名：Quaternary Research
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：85
• 期：2
• 页码：279-289
• 全文大小：2349 K

文摘

The late Quaternary sedimentary sequence in the northwestern part of the Sichuan Basin consists of five lithological units and with increasing depth include the: Chengdu Clay; Brown Clay; Red Clay; Sandy Silt; and basal Muddy Gravel. The genesis, provenance and age of the sediments, as well as the possible presence of hiatuses within this sequence are debated. Measurements of grain-size, magnetic susceptibility, quartz content, quartz δ¹⁸O values, element composition, and Sr–Nd isotopic concentrations of samples from a typical sedimentary sequence in the area provides new insights into the genesis and history of the sequence. The new data confirm that the sediments in study site are alluvial–aeolian in origin, with basal alluvial deposits overlain by aeolian deposits. Like the uppermost Chengdu Clay, the underlying Brown Clay and Red Clay are aeolian in origin. In contrast, the Silty Sand, like the basal Muddy Gravel, is an alluvial deposit and not an aeolian deposit as previously thought. Moreover, the succession of the aeolian deposits very likely contains two significant sedimentary hiatuses. Sedimentological analysis demonstrates that the source materials for the aeolian deposits in the northwestern part of the Sichuan Basin and those on the eastern Tibetan Plateau are different. Furthermore, the loess deposits on the eastern Tibetan Plateau are derived from heterogeneous local sources.