冈底斯中段厅宫地区林子宗火山岩锆石U-Pb年龄和地球化学特征  

Zircon U-Pb Ages and Geochemistry of Volcanic Rocks from the Linzizong Group in the Tingong Area in Middle Gangdise Belt

作　　者：周鹏 刘恭喜 李强 余波 ZHOU Peng;LIU Gong-xi;LI Qiang;YU Bo(Geothermal and Geological Party, Tibet Bureau of Mineral Resource Exploration and Development, Lhasa 850000, China)

机构地区：[1]西藏地质勘查局地热地质大队,拉萨850000

出　　处：《矿物岩石地球化学通报》2019年第2期352-360,共9页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国地质调查局项目(DD20160015)

摘　　要：林子宗火山岩事件是印度-亚洲大陆主碰撞过程的火山作用响应,对冈底斯带的构造演化具有重要意义。在冈底斯中段厅宫地区通过系统的LA-ICP-MS锆石U-Pb同位素测年,获得林子宗群典中组底部、年波组上部和帕那组顶部的火山岩锆石U-Pb年龄分别为(66.4±0.35)Ma、(53.6±1.5)Ma和(45±0.6)Ma。对林子宗火山岩的岩石地球化学分析表明,该火山岩具弧火山岩特征,早期表现出陆缘弧火山岩的特点,至中期年波旋回钾玄岩出现,标志着陆内岩浆作用的开始,到晚期帕那旋回则显示出陆壳重熔和地壳加厚的特征,记录了新特提斯洋消减俯冲到陆陆碰撞的地质信息。The Linzizong volcanic rock is the volcanic response of the main collision process in the Indian-Asian continental collision and thus has important geological significance for understanding the tectonic evolution of the Gangdese belt. In this study, LA-ICP-MS zircon U-Pb isotope is used to date the age of volcanic rocks. In the Tinggong area, the ages of the bottom of the Dianzhong Formation, the upper part of the Nianbo Formation and the top of the Pana Formation were(66.4±0.35) Ma,(53.6±1.5) Ma and(45±0.6) Ma, respectively. The geochemical characteristics of the rocks show that the Linzizong volcanic rocks are of arc volcanic affinity. In the early stage, the rocks are continental marginal volcanic rocks. Volcanic rocks of the Nianbo Formation are shoshonitic, indicative of the beginning of the intracontinental magmatism. In the later stage, volcanic rocks from the Pana Formation were derived from the remelting of continental crust during crustal thickening. Therefore, the Linzizong volcanic rocks record the geological evolution history of from the subduction of the new Tethys Ocean to continent-continent collision.

关 键 词：林子宗火山岩 锆石U-PB年龄 地球化学 冈底斯中段 

分 类 号：P597[天文地球—地球化学]