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Geoscience ›› 2017, Vol. 31 ›› Issue (04): 716-733.

• Petrology • Previous Articles     Next Articles

The Sedimentary Geochemical Records about the Tectonic Evolution of the East Kunlun Orogenic Belt from Early Paleozoic to Early Mesozoic

WU Ruochen1(), GU Xuexiang1,2(), ZHANG Yongmei1,2, HE Ge1, KANG Jizu3, YU Fucheng3, FENG Liqiang1, XU Jingchi1   

  1. 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
    3. Qinghai Geological Survey Institute, Xining, Qinghai 810012, China
  • Received:2017-03-23 Revised:2017-05-25 Online:2017-08-10 Published:2017-09-15

Abstract:

There are six Phanerozoic clastic rock strata distributed in the East Kunlun orogenic belt, including the Lower Cambrian Shasongwula Formation, the Middle-Upper Ordovician Nachitai Group and the Upper Carboniferous-Lower Permian Haoteluowa, the Lower Triassic Hongshuichuan, the Middle Triassic Xilikete and the Upper Triassic Babaoshan formations. Chemical index of alteration (CIA) values of the sandstones indicate the source rocks of the sandstones from the Shasongwula Formation underwent significant chemical weathering, while the other formations were opposite. Major and trace element characteristics suggest that the sandstones in the study area were primarily sourced by felsic rocks with minor intermediate igneous rocks. Moreover, through systematic comparison of the La, Ce, Th, U, ∑REE contents and the La/Sc, Th/Sc, Sc/Cr, La/Y ratios, it is suggested that the sandstones from the Shasongwula Formation and the Nachitai Group were deposited in an active continental margin setting produced by the subduction of the Proto-Tethyan oceanic crust, whereas the sandstones from the Haoteluowa Formation were deposited in a passive continental margin setting related to the rifting between the East Kunlun and Bayanhar terranes. The detritus of sandstones from the Hongshuichuan Formation were mainly derived from continental margin arc volcanic rocks that were produced by the subduction of the Paleo-Tethyan oceanic crust. Due to the both active and passive continental margin-related geochemical affinity, the sandstones from the Xilikete Formation are considered to be deposited during the initiation of the continental collision. The sandstones from the Babaoshan Formation were deposited in an active continental margin setting caused by the complete continental collision and post-collision.

Key words: East Kunlun orogenic belt, geochemistry of sandstone, provenance analysis, regional tectonic evolution, Proto-Tethys, Paleo-Tethys

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