张鹏, 姚胜, 李泳龙, 魏铭, 滕霏. 西藏谢通门县查布地区中新世火山岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2019, 38(5): 767-776.
    引用本文: 张鹏, 姚胜, 李泳龙, 魏铭, 滕霏. 西藏谢通门县查布地区中新世火山岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2019, 38(5): 767-776.
    ZHANG Peng, YAO Sheng, LI Yonglong, WEI Ming, TENG Fei. LA-ICP-MS zircon U-Pb age of the volcanic rocks in Chubb area, Xietongmen County, Tibet, and its geological implications[J]. Geological Bulletin of China, 2019, 38(5): 767-776.
    Citation: ZHANG Peng, YAO Sheng, LI Yonglong, WEI Ming, TENG Fei. LA-ICP-MS zircon U-Pb age of the volcanic rocks in Chubb area, Xietongmen County, Tibet, and its geological implications[J]. Geological Bulletin of China, 2019, 38(5): 767-776.

    西藏谢通门县查布地区中新世火山岩LA-ICP-MS锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb age of the volcanic rocks in Chubb area, Xietongmen County, Tibet, and its geological implications

    • 摘要: 西藏地勘局地质二队在谢通门县查布地区1:5万区域地质调查中新解体出一套火山岩地层,其岩性以安山岩、流纹岩、火山角砾岩及凝灰岩为主,岩层总厚度在研究区由东向西减小。用LA-ICP-MS技术对流纹岩、安山岩2件样品中的锆石进行U-Pb同位素测定,其206Pb/238U年龄加权平均值分别为:流纹岩中有2组年龄15.12±0.29Ma(MSWD=1.8,n=8)、45.39±0.56Ma(MSWD=0.93,n=14),安山岩中有4组年龄15.29±0.16Ma(MSWD=1.4,n=59)、51.9±2.3Ma(MSWD=3.5,n=7)、45.2±1.4Ma(MSWD=3.8,n=10)、38.5±0.93Ma(MSWD=1.08,n=5)。据此将该套火山岩喷发时限确定为15Ma左右,划归于布嘎寺组。

       

      Abstract: The No.2 Geobrigade of Tibet Geological Prospecting Bureau has disintegrated a set of volcanic rocks in the 1:50 thousand regional geological survey of the chubb area of Xietongmen county. It composed dominantly of andesite, rhyolite, volcanic breccia and tuff. The total thickness of the rock strata decreases from east to west in the study area. The U-Pb isotopes of zircons from rhyolite and andesite samples were determined by LA-ICP-MS. The weighted average ages of 206Pb/238U were 15.12±0.29Ma (MSWD=1.8, n=8), 45.39 ±0.56Ma (MSWD=0.93, n=14) in rhyolite and 15.29 ±0.16Ma (MSWD=1.4, n=59), 51.9 ±2.3Ma (MSWD=3.5, n=7), 45.2±1.4Ma (MSWD=3.8, n=10), 38.5±0.93Ma (MSWD=1.08, n=5) in andesite. Based on this, the eruption time limit of this suite of volcanic rocks is determined to be 15Ma or so, and it belongs to the Bugasi Group.

       

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