地质与勘探2018，Vol.54Issue(2)：286-299,14.
塔什库尔干塔吐鲁沟寒武纪岩体的厘定及其地球化学特征与构造意义
Dating and Geochemical Features of the Cambrian Pluton in Tatulugou of the Taxkorgan Landmass and Tectonic Implications
摘要
Abstract
In order to study the tectono-magmatic evolution of the Taxkorgan landmass,we have made U-Pb isotopic dating of zircon by LA-MC-ICP-MS and analysis of petrochemistry to the former Mesozoic granitic pluton in the Tatulugou area. The results show that the Tatulugou pluton is a multi-ple-stage-intruded rock body,composed mainly of the middle-late Cambrian intrusions.The weighted averages of zircon 206Pb/ 238U ages of the first three phases Cambrian pluton are 507.2±2.6Ma,506.9±1.6Ma and 507.7±3.7Ma, respectively. Their Rittmann indexes are 1.16~2.87,belonging to calc-al-kaline and high-K calc-alkaline series,of which most of aluminum saturation indexes are 1.10(0.87~1.14). The total amounts of rare earth elements (ΣREE) are (69.95-264.57)×10-6,and the REE diagram shows rightward incline with weak to moderate negative Eu anomalies(δEu=0.33~0.84). The relatively high concentration of incompatible elements Th,K,Nd and Tb and depleted Nb,Ta,Ti,P and Sr suggest that this rock is weakly peralumi-nous or quasi-aluminous I-type granite associated with subduction of oceanic crust. The material source of the magma may be from partial melting of the upper mantle and thickened basaltic lower crust. During the rising process,the magma was contaminated by the upper crust,and thus had the evolution characteristics of high Si,rich alkali but poor Mg,Fe,and Ti.This Cambrian pluton formed in an oceanic subduction environment and in the transition pe-riod from subduction to syncollisional setting,consistent with the processes of subduction and closure of Proto-Tethys during(456±30)~698.4Ma. These lines of evidence suggest its formation is attributed to the subduction of Proto-Tethys,and the Taxkorgan landmass might be in an environments of ocean crust subduction and volcanic arc in the Middle-Late Cambrian epoch.关键词
LA-MC-ICP-MS/锆石U-Pb年龄/地球化学/构造意义/寒武纪岩体/塔吐鲁沟 塔什库尔干塔吐鲁沟Key words
LA-MC-ICP-MS/zircon U-Pb ages/geochemistry/tectonic significance/Cambrian pluton/Taxkorgan Tatulugou分类
天文与地球科学引用本文复制引用
和志鹏,刘继顺,康亚龙,王天国,孙连宇..塔什库尔干塔吐鲁沟寒武纪岩体的厘定及其地球化学特征与构造意义[J].地质与勘探,2018,54(2):286-299,14.基金项目
新疆维吾尔自治区地质勘查基金(编号:XJDKJJZ2011-2)资助. （编号:XJDKJJZ2011-2）
