Zircon SHRIMP U-Pb ages of the Gangdese Batholith and implications for Neotethyan subduction in southern Tibet

Da Ren Wen, Dunyi Liu, Sun Lin Chung, Mei Fei Chu, Jianqing Ji, Qi Zhang, Biao Song, Tung Yi Lee, Meng Wang Yeh, Ching Hua Lo

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    424 Citations (Scopus)

    Abstract

    The Trans-Himalayan magmatism, which occurred extensively in the Lhasa terrane of southern Tibet, has long been related to the Neotethyan subduction before the India-Asia collision. To better delineate the magmatic duration, we report a geochronological study with 25 SHRIMP zircon U-Pb ages from the Gangdese Batholith that represents the largest Trans-Himalayan plutonic complex. The results suggest two distinct stages of plutonism in the Late Cretaceous (ca. 103-80 Ma) and early Paleogene (ca. 65-46 Ma), respectively. Our new data confirm if not refine the notion that a Gangdese magmatic gap or quiescent period existed between ca. 80 and 70 Ma. It is furthermore identified that the early stage ended with adakitic intrusion and the latter stage is marked by a peak activity at ca. 50 Ma. We attribute the cessation of the early stage, and following magmatic gap, to a flattening of the northward Neotethyan subduction, and the initiation of the latter stage to rollback of the subducted slab. The proposed scenarios can also account for the southward migration and intensification of Cretaceous to Paleogene volcanism in the Lhasa terrane that demonstrates a coeval, eruptive "flare-up" event around 50 Ma, interpreted as the result of detaching the Neotethyan oceanic slab from the adherent, more buoyant Indian continental lithosphere owing to the India-Asia collision. Our model is, moreover, in general accord with sedimentary and structural geologic records from southern Tibet where subduction-related orogenesis appears to have evolved through time before India started colliding Asia.

    Original languageEnglish
    Pages (from-to)191-201
    Number of pages11
    JournalChemical Geology
    Volume252
    Issue number3-4
    DOIs
    Publication statusPublished - 2008 Jul 15

    Keywords

    • Gangdese Batholith
    • Neotethyan subduction
    • Tibet
    • Zircon U-Pb dating

    ASJC Scopus subject areas

    • Geology
    • Geochemistry and Petrology

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