ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    西昆仑大红柳滩黑云母二长花岗岩岩石成因:来自锆石U-Pb年龄及Li-Hf同位素的证据

    Petrogenesis of Dahongliutan Biotite Monzogranite in Western Kunlun Orogen: Evidence from Zircon U-Pb Age and Li-Hf Isotope

    • 摘要: 大红柳滩岩体位于西昆仑造山带东段,主要由黑云母二长花岗岩、二长花岗岩及二云母花岗岩组成。笔者对大红柳滩岩体东南部的黑云母二长花岗岩进行了锆石LA-ICP-MS U-Pb定年,测得黑云母二长花岗岩的侵位年龄分别为(214±1.8)Ma,说明大红柳滩岩体为印支晚期岩浆活动的产物。大红柳滩岩体具有高δ7Li(0.76‰~3.25‰)和低Li(5.04×10-6~52.22×10-6)同位素地球化学特征;黑云母二长花岗岩样品的锆石εHft)值介于-1.86~2.16,二阶段模式年龄为1 113~1 368 Ma;在εHft)-锆石U-Pb年龄图解中,所有数据点均落在球粒陨石演化线附近。综合研究表明,大红柳滩岩体的原始岩浆是由地幔与中元古代地壳2个单元形成的混合岩浆。

       

      Abstract: The Dahongliutan pluton is located in the eastern part of the West Kunlun Orogenic Belt and is mainly consisted of biotite monzonitic granite, monzonitic granite and two mica granite. The Zircon LA-ICP-MS U-Pb dating of biotite monzonitic granite in the southeastern part of Dahongliutan intrusion shows that the emplacement age of biotite monzonitic granite is 214+1.8 Ma, indicating that the Dahongliutan pluton was formed in the Late Indosinian. The Dahongliutan pluton has higher value of δ7Li(0.76‰~3.25‰) and lower content of lithium(5.04~52.22)×10-6. The biotite monzonitic granite has zircon εHf(t) values of -1.86 to 2.16, and the two-stage mode age ranged between 1113 and 1368 Ma. In the εHf(t) vs. age diagram,all the data points lie near the chondrite evolution line. The comprehensive research shows that the Dahongliutan pluton has derived from a mixed magma of mesoproterozoic crust and mantle.

       

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