摘要
近年在西藏东南部特提斯喜马拉雅带东段大规模白垩纪火山岩的发现受到了很多学者的关注,笔者于藏南隆子地区桑秀组地层中发现一套以英安岩和粗玄岩为主的双峰式火山岩组合,英安岩的SHRIMP锆石U-Pb年龄为134.9±2.3Ma,成岩时代为早白垩世,与措美大火成岩省岩浆活动峰期时间一致。地球化学证据表明,粗玄岩富Ti O_2、TFe O和P_2O_5,无明显HFSE亏损,英安岩Th、Nb、Zr、Y含量较高,而相对亏损P和Ti,Eu的负异常明显。粗玄岩可能是Kerguelen地幔柱与岩石圈地幔相互作用的产物,而英安岩的形成与地壳深熔作用有关。本文结果为措美大火成岩省的东延提供了地质年代学和地球化学方面的证据,并对了解与雅鲁藏布江洋盆构造演化有关的一些关键地质问题可能具有重要意义。
Growing attention has been focused on the extensive igneous rocks in eastern Tethyan Himalaya,southeastern Tibet.A suite of bimodal volcanics assemblage composed of dacite and dolerite are distributed in the Sangxiu formation in the Longzi area,south Tibet by the author.SHRIMP U Pb zircon age of 134.9±2.3 Ma has been obtained from dacite.the geological age of the dacite is Early Cretaceous,coeval with the peak age of the Comei—Bunbury LIP.Geochemical analysis indicates that the dolerites are enriched in TiO2,TFeO and P2O5,HFSE loss is not obvious,and the dacite are characterized by Th,Nb,Zr,Y ,enrichment and P,Ti trough,obvious loss of Eu.These dolerites could be the products of interaction between lithosphere and mantle plume,and the dacite originated from the anatexis ensialic continental crust.This proposes that this interaction could play an important role in understangding the key geological problems concerned with tectonic evolution of Yarlung Zangbo Oceanic Basin.
出处
《地质论评》
CAS
CSCD
北大核心
2016年第4期945-954,共10页
Geological Review
基金
区域地质矿产调查项目成果
工作项目名称:西藏古堆地区金锑多金属矿产远景调查
工作项目编码:1212011121236
承担单位:受中国人民武装警察部队黄金指挥部委托
由中国人民武装警察部队黄金第十一支队承担~~