Constraints of Precambrian basement in Ren Co area,Tibet on the origin of the North Lhasa terrane
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P597;P542

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    Abstract:

    The North Lhasa terrane is one of the most widely exposed areas of Precambrian rocks in the Tibetan Plateau, but the Neoproterozoic tectonic evolution of the terrane and its role in the supercontinent evolution have been controversial. Focusing on this scientific problem, this paper collects and arranges the isotopic chronology, geochemistry and isotopic geochemistry data of the Precambrian Nyainqentanglha Group in Ren Co area of the North Lhasa terrane, and finds three periods of Neoproterozoic magmatic-sedimentary-metamorphic records: ① 925 ~ 886 Ma, the rock association is MORB-type metamorphic basic rocks and metamorphic sedimentary rocks, representing the embryonic oceanic crust and associated sediments in the latest stage of continental rift; ② 822 ~ 671 Ma, mainly plagioclase amphibolites and granitic gneisses, whose protoliths are tholeiites, calc-alkaline basalts and A2-type granite, which were formed in the process of oceanic subduction together with the coeval amphibolite-facies metamorphism; ③ 658 ~ 646 Ma, including intermediate-basic intrusive and volcanic rocks and eclogite-amphibolite-facies metamorphic rocks, which jointly record the process of slab break-off in a collision zone. The above three magmatic-sedimentary-metamorphic records are consistent with the evolution of the Mozambique Ocean, corresponding to the embryonic stage, decline stage and end stage of the Wilson cycle respectively. In addition, the temporal-spatial distribution of Andean-type magmatism in the northern margin of Gondwana supercontinent are further constrained by the Ediacaran magmatic rocks in the Nyainqentanglha Group. Based on this study and previous results, we suggest that the North Lhasa terrane drifted away from Africa in the Tonian, experienced the subduction-collision processes of the Mozambique Ocean in the Cryogenian, and then located in the northern East African orogen in the Ediacaran, and influenced by the Andean-type magmatism along the Gondwanan Proto-Tethyan margin in the Ediacaran-Cambrian.

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胡培远,翟庆国,赵国春,唐跃,杨宁,李金勇,2022,西藏仁错地区前寒武纪基底对北拉萨地块起源的约束[J].岩石矿物学杂志,41(2):281~302. HU Pei-yuan, ZHAI Qing-guo, ZHAO Guo-chun, TANG Yue, YANG Ning, LI Jin-yong,2022,Constraints of Precambrian basement in Ren Co area, Tibet on the origin of the North Lhasa terrane[J]. Acta Petrologica et Mineralogica,41(2):281~302.

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History
  • Received:September 22,2021
  • Revised:December 05,2021
  • Adopted:
  • Online: March 21,2022
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