Provenance and weathering control on river bed sediments of the eastern Tibetan Plateau and the Russian Far East

We investigated the petrography and major, trace and rare earth element compositions of the bed sediments from the large rivers draining the eastern Tibetan Plateau (ETP) - the Huang He (Yellow), Chang Jiang (Yangtze), Hong He (Red), Mekong and Salween. The combined drainage spans tropical, temperate and and climate zones. In addition, samples from the Lena River, draining the Verkhoyansk and Sette-Daban ranges in an arctic to sub-arctic climate zone in Siberia, were also studied for their major and trace element composition. The sub-angular texture, the quartz: feldspar: rock fragment classification in the lithic arenite field, and the relatively low chemical index of alteration (CIA: 42-79), indicate that these sediments are texturally, petrographically and chemically immature, and immobile trace elements can be used to obtain some information about the lithologic provenance. The ETP river sediments are felsic and similar to the Upper Continental Crust with the Salween most felsic and the Lena most mafic. The sediments show a gradation in maturity that is not clearly related to present climatic or physiographic regime. This suggests that maturity itself is a relict feature inherited from previous sedimentary cycles. The high physical erosion in such high energy and relief systems seems to inhibit intense weathering and manifests a provenance control from local rocks on the sediment compositions. (C) 2008 Elsevier B.V. All rights reserved.