石玉莲, 霍清, 潘鑫, 田滔, 李生虎. 青海龙羊峡地区侵入岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2018, 37(7): 1246-1257.
    引用本文: 石玉莲, 霍清, 潘鑫, 田滔, 李生虎. 青海龙羊峡地区侵入岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J]. 地质通报, 2018, 37(7): 1246-1257.
    SHI Yulian, HUO Qing, PAN Xin, TIAN Tao, LI Shenghu. LA-ICP-MS zircon U-Pb age of the intrusive rocks in Longyangxia area of Qinghai Province and its geological significance[J]. Geological Bulletin of China, 2018, 37(7): 1246-1257.
    Citation: SHI Yulian, HUO Qing, PAN Xin, TIAN Tao, LI Shenghu. LA-ICP-MS zircon U-Pb age of the intrusive rocks in Longyangxia area of Qinghai Province and its geological significance[J]. Geological Bulletin of China, 2018, 37(7): 1246-1257.

    青海龙羊峡地区侵入岩LA-ICP-MS锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb age of the intrusive rocks in Longyangxia area of Qinghai Province and its geological significance

    • 摘要: 青海龙羊峡地区侵入体岩石类型为正长花岗岩、二长花岗岩及花岗闪长岩,岩石中Al2O3=11.78%~15.11%,K2O=3.57%~5.58%,A/NK=1.14~1.63,A/CNK=0.87~0.97,TFeO/(TFeO+MgO)=0.74~0.91,岩石具偏铝质中-高钾钙碱性花岗岩特征。用LA-ICP-MS测得龙羊峡侵入岩体的正长花岗岩和二长花岗岩中的锆石206Pb/238U年龄为243.5±2.9Ma(MSWD=5.2)和247.2±1.7Ma(MSWD=0.97),这2个年龄被解释为岩体侵位年龄。代表了印支运动在西秦岭造山带西段与东昆仑造山带转换衔接部位的共和坳拉谷的构造演化的地质记录。青海龙羊峡地区侵入岩体的形成时代及构造环境的确定,对研究共和坳拉谷的构造演化及动力学机制具有重要意义。

       

      Abstract: The intrusive rock types of Longyangxia area in Qinghai Province include syenogranite, monzonitic granite and granodiorite, The rocks have the data Al2O3=11.78%~15.11%, K2O=3.57%~5.58%, A/NK=1.14~1.63, A/CNK=0.87~0.97, and TFeO/(TFeO + MgO)=0.74~0.91, exhibiting the characteristics of metaluminous intermediately high-K calc-alkaline granite. The LAICP-MS detection shows that the 206Pb/238U ages of zircon in syenogranite and monzonitic granite are respectively 243.5 ±2.9Ma (MSWD=5.20) and 247.2±1.7Ma (MSWD=0.97), which are interpreted as the rock emplacement age and represent the geological record of Indosinian Movement's tectonic evolution in the Gonghe aulacogen located in the conjugating and transferring part between the western section of West Qinling orogenic belt and the east Kunlun orogenic belt. The determination of the formation epoch and tectonic environment of the intrusive rocks in Longyangxia area of Qinghai plays a crucial role in the research on the tectonic evolution and dynamics mechanism of Gonghe aulacogen.

       

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