西藏冈底斯带中部南木林地区林子宗群火山岩锆石U-Pb年龄和地球化学特征  

Zircon U-Pb age and geochemistry of volcanic rock of Linzizong Group in Nanmulin area of Middle Gangdise belt, Tibet

作　　者：张运昌 陈彦[1] 杨青 王廷栋 毛双喜 ZHANG Yunchang;CHEN Yan;YANG Qing;WANG Tingdong;MAO Shuangxi(Sichuan Institute of Nuclear Geology,Chengdu 610041,Sichuan,China;Chengdu University of Technology,Chengdu 610059,Sichuan,China)

机构地区：[1]四川省核工业地质调查院,四川成都610041 [2]成都理工大学,四川成都610059

出　　处：《地质通报》2019年第5期719-732,共14页Geological Bulletin of China

基　　金：中国地质调查局项目《西藏卡孜地区1:5万区域地质调查(H45E015019 H45E015020 H45E015021 H45E015022)》(编号:121201010000150014-39)

摘　　要：林子宗群火山岩广泛分布在冈底斯带上,其岩石学特征及所代表的区域不整合事件被认为与特提斯洋俯冲消减到印度-亚洲大陆碰撞转变有关。对冈底斯带南木林地区的林子宗群火山岩进行了LA-ICP-MS锆石U-Pb测年及地球化学研究,获得林子宗群火山岩帕那组LA-ICP-MS锆石U-Pb年龄为46.08±0.47Ma、49.00±1.30Ma,对比冈底斯带其他地区已发表的年龄数据,认为印度-亚洲大陆碰撞(在西藏南部)的时间,东部可能依次早于中部和西部。地球化学特征表明,冈底斯带南木林地区林子宗群火山岩具有碰撞后地壳加厚背景下产生的弧火山岩特征,应为新特提斯洋俯冲消减到印度-亚洲大陆碰撞构造背景下形成的。The volcanic rocks of Linzizong Group are widely distributed in the Gangdise belt. Their petrological characteristics together with regional unconformity events are considered to be related to the transform from Tethys Ocean subduction to the collision of Indian- Asian continent. In this paper, LA- ICP- MS zircon U- Pb age and geochemistry were investigated for the volcanic rocks in Linzizong Group, and the result indicates that the LA-ICP-MS zircon U-Pb ages of Pana Formation volcanic rocks of Linzizong Group are 46.08 ± 0.47Ma and 49.00 ± 1.30Ma. Compared with the related age data of other regions of the Gangdese belt, the authors hold that the time of the India-Asia continent collision (in southern Tibet) in the eastern part may be earlier than that of the central and western regions. Additionally, the geochemical characteristics show that the Linzizong volcanic rocks were generated under the background of the crustal thickening after collision in the Nanmulin area of Gangdese belt, and were formed in the background from the transform from the new Tethys Ocean subduction to the collisional structure of the Indian-Asian continent.

关 键 词：锆石U-PB 年龄 林子宗群火山岩 地球化学特征 南木林 

分 类 号：P597.3[天文地球—地球化学] P588.14[天文地球—地质学]