西藏中冈底斯扎布耶茶卡北部晚侏罗世则弄群火山岩的锆石U-Pb年代学及其成因意义  

Zircon U-Pb Ages of the Late Jurassic Volcanic Rocks from the Zenong Group in the North of Zabuyechaka Area, Tibet and Its Geological Significances

作　　者：叶春林[1] 黄柏鑫[1] 王燚 侯云岭 贾小川[1] 杨学俊[1] 王国光[2] 吕志伟 YE Chunlin;HUANG Baixin;WANG Yi;HOU Yunling;JIA Xiaochuan;YANG Xuejun;WANG Guoguang;LYU Zhiwei(Geological Survey of Sichuan Province,Chengdu 610081,China;State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]四川省地质调查院,成都610081 [2]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210023

出　　处：《高校地质学报》2018年第4期525-535,共11页Geological Journal of China Universities

基　　金：中国地质调查局《冈底斯-喜马拉雅铜矿资源基地调查》项目(121201010000150014-13)资助。

摘　　要：冈底斯带晚中生代构造演化模式一直存在争议。此次研究了中冈底斯带扎布耶茶卡北部区域则弄群火山岩的野外特征和锆石U-Pb年龄。锆石U-Pb定年结果表明,扎布耶茶卡北部则弄群火山岩主要喷发于154.2~142.1 Ma。研究首次获得晚侏罗世的则弄群火山岩年龄为154 Ma,比前人提出的则弄群火山岩浆活动起始时间(130 Ma)提前了24 Ma,据此将则弄群的时代定为晚侏罗世至早白垩世。根据研究获得的最新年代学数据,结合冈底斯带火山岩的前人研究资料,显示冈底斯带中生代弧火山岩具有从南向北逐渐年轻的趋势。因此,最早期南冈底斯弧中生代火山岩可能与新特提斯洋板片北向俯冲有关,晚侏罗世至早白垩世的中冈底斯带弧火山岩受到了新特提斯洋板片北向俯冲和班公湖-怒江洋板片南向俯冲的双重影响,早白垩世中期的北冈底斯带弧火山岩则与班公湖-怒江洋板片的南向俯冲密切相关。研究成果为冈底斯带晚中生代构造演化模式提供了火山岩方面的新证据。The Late Mesozoic tectonic evolution models of the Gangdese belt in Tibet remain controversial.We present here the field observations and zircon U-Pb ages of the volcanic rocks from the Zabuyechaka in the Mid-Gangdese belt.Zircon U-Pb dating results suggest that the volcanic rocks of the Zenong Group were formed during 154.2-142.1 Ma.This study first obtain the Late Jurassic ages of the Zenong Group(154 Ma),which is approximately 24 m.y.older than previously published data.The data from this study,and combined with previously published data on Mesozoic volcanic rocks in the whole Gangdese belt show obviously northward younger trends.It suggests that the Early Jurassic arc volcanic rocks in the south Gangdese belt were associated with the subduction of the Neo-Tethys oceanic plate,and the Middle-Early Cretaceous arc volcanic rocks in the north Gangdese belt were related to the subduction of the Bangonghu-Nujiang oceanic plate,and the Late Jurassic to Early Cretaceous arc volcanic rocks in the middle Gangdese belt were jointly affected by the northward subduction of the Neo-Tethys and the southward subduction of the Bangonghu-Nujiang oceanic plates.This study provides new evidence for the Late Mesozoic tectonic evolution of the Gangdese belt.

关 键 词：LA-ICP-MS 锆石U-Pb年龄 则弄群火山岩 中冈底斯带 构造演化 

分 类 号：P597[天文地球—地球化学]