T130 Integrated Tectono-Sedimentary Records in the Tibetan Plateau and Adjacent Areas (Posters)

Monday, 23 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

DETRITAL ZIRCON AGE OF TURBIDITES FROM THE BEISHAN OROGEN, NW CHINA

Paper number: T130-3
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

  • Qianqian Guo Presenting Author
    Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Beijing
  • Quanlin Hou
    Chinese Academy of Sciences, Beijing
  • Quanlin Hou
    University of Chinese Academy of Sciences, Beijing
  • Wenjiao Xiao
    Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing

Abstract

The Altaids, as one of the biggest accretionary orogens in the world, is situated between the Siberia and Baltica cratons to the north and the Tarim and North China cratons to the south. Beishan orogenic belt, encompassed the final attachment of the Tarim and North China Cratons to the southern accretionary orogenic collages of the Southern Altaids as far as the Siberian Craton, linked the Tianshan and Xingmeng orogeny. The duration and architecture of the Beishan orogen is controversial and has led to different reconstructions of the Altaids. Proposals of the latest suture in Beishan orogen varies from Devonian to End-Permian.

Turbidites are the most common and archetypal deposits forming deep-marine clastic systems, and those emplaced in an accretionary orogenic belt exhibit younging in the accretionary direction. The Paleozoic turbidites in Beishan are mainly distributed in the Yingmaotuo, Dundunshan, Liuyuan, and Heishankou area from north to south. The εNd(t) values of Yinmaotuo turbidites range from -12.9 to -14.0 Ga, with model ages (TDM) of 2.24-2.28 Ga, indicating they were derived from Proterozoic crust. The εNd(t) values of Dundunshan turbidites range from -5.0 to -9.1, with model ages (TDM) of 1.47-1.82 Ga that are lower than average value (1.9 Ga) of globe sedments. Calculated initial εNd(t) values of the Liuyuan turbidites range from -0.5 to 1.1, and the TDM model ages from 1.06 to 1.22 Ga (Figure 5). The Heishankou turbidites have lower 147Sm/144Nd and 143Nd/144Nd ratios, and result in lower εNd(t) values (-4.2 to -2.4) and similar TDM model ages (1.09 to 1.36 Ga). Contrasting isotopic characteristics, together with the sedimentary age, may provide new constrains on the latest suture zone and the architecture of the Beishan orogen.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-340635

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