中天山东段花岗岩类铷-锶年代学及构造演化  

Rb—Sr GEOCHRONOLOGY OF GRANITES IN THE EAST SECTION OF THE MID-TIANSHAN BELT AHD ITS TECTONIC EVOLUTION

作　　者：顾连兴[1] 杨浩[1] 陶仙聪[1] 严正富[1] 李惠民[1] 王金东 刘彦东 

机构地区：[1]南京大学地球科学系 [2]新疆地矿局第六地质大队

出　　处：《桂林冶金地质学院学报》1990年第1期49-55,共7页

基　　金：国家七五计划加速查明新疆矿产资源综合研究项目(305项目)

摘　　要：对中天山东段具有代表性的7个花岗岩体作了Rb-Sr年代学研究,其等时线年龄和^(87)Sr/^(86)Sr初始值分别为:平顶山岩体,913.8±4.5 Ma,0.7189;天湖东岩体,696.9±5.7Ma,0.7124;选矿场后山岩体,724.0±8.1Ma,0.7151;砂垄东岩体,470.0±3.0Ma,0.7058;尾亚岩体内带,379.1±1.4Ma,0.7027;尾亚岩体中带,379.7Ma;白石头泉岩体,209.6±9.6Ma,0.9873。它们分别归属雪峰、期澄江期、加里东期和印支期。元古代花岗岩主要是同造山的原地-半原地片麻状花岗岩;加里东花岗岩为一些弧立分布的等轴-短轴状侵入体,岩性主要为花岗闪长岩-二长花岗岩;印支期花岗岩则以高度演化的二云母-天河石花岗岩为特征。塔里木古陆北缘除了中、晚元古代大陆增生外,还发育一条加里东期优地槽褶皱带,而中天山则是该代地槽带中的一个中、晚元古代中间地块(地层地体)。至上古生代,中天山东段具有被动大陆边缘的性质,因而明显缺乏海西期岩浆活动。Geochronological researches were made on seven representative graniticbodies in the east section of the mid-Tianshan tectonic belt.Rb-Sr isochronages and ^(87)Sr/^(86)Sr initial ratioes obtained for these seven bodies are: Ping-dingshan augen-gneissic monzonitic granite, 913.8±4.5Ma, 0.7189; Tianhu-dong gneissic granodiorite, 696.6±5.7Ma, 0.7124; Back Hill gneissic grano-diorite, 724.0±8.1Ma, 0.7151; Shalongdong monzonitic granite, 470.0±3.0Ma, 0.7058; Weiya monzonitic granite (internal zone) 379.1±1.4Ma, 0.7027;Weiya granodiorite and monzonitic granite intermediate zone), 379.7Ma,Baishitou spring amazonite granite, 209.6±9.6 Ma, 0.9873. They were formedas a result of the Xuefengian, the Chengjiangian, the Caledonian and thelndosinian thermo-tectonic events, respectively. The Proterozoic granitesare mainly autoch-parautochthonous synkinematic ones characterized bygneissic structures, while those of the Caledonian cycle are typical ofseparately distributed equi-brachy axial intrusives with massive structureand granodioritic to monzonitic granite compositions, and the Indosiniangranites are distinctive in their highly evolved two-mica and amazonitecomponents. It is indicated that in addition to a mid-to late Proterozoic accretionaryzone to the northern margin of the Talimu ancient continent, there exists aCaledonian eugeosynclinal folded belt here within which the mid-Tianshanzone can be regarded as a mid-to late Proterozoic intermediate block (a stra-tigraphic terrain). The contrastive lack of Hercynian magmation may beascribed to its upper Paleozoic tectonic setting at a passive continental margin.

关 键 词：花岗岩 铷-锶年龄 构造 演化 

分 类 号：P588.121[天文地球—岩石学]