东天山觉罗塔格带东段早志留世中酸性侵入岩的年代学、地球化学及构造意义  

Geochronology,Geochemistry and Tectonic Implications of Early Silurian Intermediate-Acid Intrusive Rocks in East of Jueluotage Belt,Eastern Tianshan

作　　者：于介禄 于介江[1] 杨万志 张元厚[1] 郭秀玮 Yu Jielu;Yu Jiejiang;Yang Wanzhi;Zhang Yuanhou;Guo Xiuwei(College of Earth Sciences ,Jilin University , Changchun 130061,China;Xinjiang Institute of Geological Survey ,Urumqi 830000, China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]新疆维吾尔自治区地质调查院,乌鲁木齐830000

出　　处：《吉林大学学报（地球科学版）》2019年第3期690-708,共19页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41672050);新疆维吾尔自治区地质勘查基金管理中心项目(Y14-5-LQ05)~~

摘　　要：为了确定东天山觉罗塔格带东段玉海地区中酸性侵入岩的形成时代、源区性质及其构造属性,本文对该区中酸性侵入岩进行了系统的LA-ICP-MS锆石U-Pb定年、全岩地球化学以及Sr-Nd同位素分析。2个样品中的锆石在CL图像上具明显振荡环带,Th/U值为0.28～0.59,指示其岩浆成因。对岩浆锆石定年结果表明,它们主要形成于早志留世(433.2～431.2Ma),代表了寄主岩石的形成时代。样品w(SiO_2)=57.88%～69.01%,w(Na_2O)=3.46%～5.07%,w(K_2O)=0.50%～1.65%,Na_2O/K_2O=4.26～6.79,Mg#=45.1～52.3,A/CNK=0.89～1.00;稀土配分模式呈右倾型,LREE/HREE=5.55～11.47,(La/Yb)N=4.18～13.54,δEu=0.82～1.25;在微量元素蛛网图上表现为大离子亲石元素(Ba、U、K、Sr等)相对富集和高场强元素(Th、Ti、Nb、Ta)相对亏损;全岩εNd(t)值介于6.1～7.0之间。研究表明,早志留世中酸性侵入岩的岩浆源区主要为年轻地壳物质,结合火成岩的组合特征、岩浆作用性质以及区域构造演化历史,认为早志留世中酸性侵入岩形成于康古尔洋板片向北(吐—哈地块)俯冲的活动大陆边缘环境,从而将康古尔大洋板片北向俯冲的时限追溯至早志留世。In order to ascertain the formation age,source and tectonic properties of the intermediateacid intrusive rocks in the Yuhai area of the eastern Jueluotage belt in the eastern Tianshan,this paper systematically presents LA-ICP-MS zircon U-Pb geochronology,whole rock geochemistry and Sr-Nd isotopes data of the rocks in this area.The selected zircons of two samples show obvious oscillation zoning in cathodoluminescence(CL)images,and have Th/U value of 0.28-0.59,indicating a magmatic origin.The zircon U-Pb dates indicate that they formed in the Early Silurian of(433.2-431.2)Ma,representing the emplacement age of these host rocks.These samples have w(SiO2)=57.88%-69.01%,w(Na2O)=3.46%-5.07%,w(K2O)=0.50%-1.65%,Na2O/K2O=4.26-6.79,Mg#=45.1-52.3,and A/CNK=0.89-1.00;the rare earth element distribution patterns are right-slipped,LREE/HREE=5.55-11.47,(La/Yb)N=4.18-13.54,andδEu=0.82-1.25;the trace element spider diagrams show that they are enriched in LILE(Ba,U,K and Sr),moderately depleted of HFSE(Th,Ti,Nb and Ta);the value ofεNd(t)of the whole rock is between 6.1 and 7.0.The study shows that the magma source of the intermediate-acid intrusive rocks in the Early Silurian is mainly young crustal material.Combining with the characteristics of igneous rock association,magmatism and regional tectonic evolution history,it is considered that the intermediate-acid intrusive rocks of the Early Silurian were formed in the active continental margin environment under the northward subduction of the Kanggur Ocean plate(Turpan-Hami block).Thus,the time of the Kanggur plate subduction can be traced back to the Early Silurian.

关 键 词：东天山觉罗塔格带东段 早志留世 中酸性侵入岩 年代学 地球化学 构造意义 

分 类 号：P588.12[天文地球—岩石学] P59[天文地球—地质学]