东天山石炭纪—二叠纪花岗质侵入岩的地球化学及地质意义  

Geochemical and geological implications of granitic intrusive rocks in Carboniferous to Permian in eastern Tianshan of Xinjiang

作　　者：董庆吉[1] 丛源[2] 肖克炎[2] 

机构地区：[1]中国地质调查局,北京100037 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《地质学刊》2014年第4期517-529,共13页Journal of Geology

基　　金：中国地质调查局项目"全国重要矿产总量预测"(1212010733806);国家科技支撑计划项目"西部优势矿产资源潜力评价技术及应用研究"(2006BAB01A01)资助

摘　　要：东天山吐哈盆地南缘至喀拉塔格—星星峡地块,晚古生代花岗质侵入岩岩石类型主要有花岗闪长岩、二长花岗岩、石英闪长岩、石英二长闪长岩。岩石地球化学特征表明：Si O2质量分数为57.3%~77.76%,全碱（K2O＋Na2O）质量分数为4.14%~10.49%,Ca O质量分数为0.49%~6.56%,Al2O3质量分数为11.39%~14.76%,铝饱和指数（A/CNK）为0.77~1.04,属于高钾钙碱性系列—钾玄质系列的准铝质花岗岩。稀土总量较高且轻稀土富集,富集Rb、Th、U、K、Pb,而亏损Nb、Ta、Ti、P,无明显负Eu异常。区域构造背景、岩石学和地球化学特征综合分析显示,东天山石炭纪—二叠纪花岗质侵入岩,是后碰撞构造演化阶段岩浆活动的产物,主要由幔源岩浆底侵引起的地壳物质部分熔融所形成的钙碱性花岗闪长质岩浆经高度演化及分异结晶作用而成。The Carboniferous to Permian granitic rocks in eastern Tianshan were widespread and consisted of granodiorite,monzonitic granite,quartz diorite and quartz monzonitic granite. They were bounded to the southern Turfan-Hami Basin and the northern Kalatarge-Xingxingxia block. The data of rock geochemistry showed that granitic rocks were high-K calc-alkaline series and of I-type granite with peraluminous characteristics. Petrogeochemistry exhibited that SiO 2content was of 57. 3% ~77. 76%,total alkali（ K2 O ＋ Na2O）content 4. 14% ~10. 49%,Al2O3 content 11. 39% ~14. 76%,with A / CNK values of 0. 77 ~1. 04. The granitic rocks were characteristic of total rare earth,enrichment of the LREE,enriched in Rb,Th,U,K,Pb,depleted in Nb,Ta,Ti,P. In addition,granitic rocks were lack of negative anomaly in Eu. Combining with the integration analysis of regional geology and geochemical characteristics,the authors proposed that the Carboniferous to Permian granitic rocks were formed during post-collision period. The granitic magmas were probably originated from crystallization / differentiation of earlier calc-alkaline granodioritic magmas formed by partial melting of crust due to under plated mantle source magmas.

关 键 词：花岗岩 地球化学 构造环境 石炭纪—二叠纪 吐哈盆地 东天山 新疆 

分 类 号：P588.12[天文地球—岩石学] P59[天文地球—地质学]