LIU Anlin, ZHU Dicheng, WANG Qing, ZHANG Lixue, LI Shimin, ZHANG Liangliang, ZHAO Zhidan. LA-ICP-MS zircon U-Pb age and origin of the Linzizong volcanic rocks from Milashan, southern Tibet[J]. Geological Bulletin of China, 2015, 34(5): 826-833.
    Citation: LIU Anlin, ZHU Dicheng, WANG Qing, ZHANG Lixue, LI Shimin, ZHANG Liangliang, ZHAO Zhidan. LA-ICP-MS zircon U-Pb age and origin of the Linzizong volcanic rocks from Milashan, southern Tibet[J]. Geological Bulletin of China, 2015, 34(5): 826-833.

    LA-ICP-MS zircon U-Pb age and origin of the Linzizong volcanic rocks from Milashan, southern Tibet

    • Much attention has been paid to the Linzizong volcanic rocks which are extensively developed along the strike of southern and central Lhasa Terrane because these rocks are generally considered to document the history of late subduction of the Neo-Tethyan ocean lithosphere and subsequent India-Asia collision. However, reliable age data for the Linzizong volcanic in a regional scale rocks remain very insufficient. In this paper, the authors performed zircon U-Pb dating, zircon Hf isotope determination, and whole-rock element geochemical study of a volcanic breccia-bearing rhyolite sample collected from the Linzizong volcanic rocks in Milashan, eastern segment of the southern Lhasa Terrane. Eighteen analyses of zircons from this sample yielded a zircon 206Pb/238U age of 60.1±0.9Ma, coeval with the andesitic volcanism documented in the lowerest Dianzhong Formation in Linzhou Basin. This sample is characterized by significant depletion of middle rare earth element (MREE) and low abundances of heavy REE, with positive zircon εHf(t) values ranging from +8.5 to +18.8. Such geochemical characteristics indicate that this sample probably originated from partial melting of thick and juvenile lower crust materials under a transitional condition from amphibolite to eclogite facies. At present, it is still difficult to explore the tectonic implications of the differences in REE abundances observed from the ca.60Ma Linzizong volcanic rocks along the strike of the Lhasa Terrane.
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