新疆阿尔泰山西段冲乎尔地区侵入岩岩浆序列确立及构造意义

发布时间：2018-04-12 11:33

本文选题：锆石U-Pb + LA-ICP-MS　；参考：《新疆大学》2016年硕士论文

【摘要】：研究区位于额尔齐斯大断裂北侧,西北为国界。研究区内岩浆活动较强,岩石类型复杂,前人对其作过较多的地质工作,但对阿尔泰造山带西段侵入岩研究较少。本文通过同位素年代学、岩石学、地球化学及野外地质观察等手段,对新疆阿尔泰造山带西段冲乎尔地区侵入岩的岩浆序列进行了研究,对研究区侵入岩岩浆序列、岩石成因及构造环境研究提供重要依据。取得了以下认识:本文对研究区内1:5万区调成果的基础上,选择了4个岩体,并根据路线信息、剖面信息及锆石U-Pb年代学数据,最后确定了其侵入序列、岩石成因类型及构造环境。通过U-Pb测年数据分析,研究区内侵入岩岩浆序列划分为奥陶纪侵入序列和晚志留-早泥盆纪侵入序列等两个序列;其LA-ICP-MS年龄为:喀拉斯片麻状黑云母二长花岗岩473.3±2.9Ma,比列乌提溪黑云母花岗岩469.8±2.9Ma,阿尤特山东南破片麻状黑云母二长花岗岩455.3±3.1Ma。铁列里克片麻状英云闪长岩420.6±3.0Ma及414.8±2.6Ma。奥陶纪序列侵入岩体具有一致的地球化学特征,高硅、高碱、高钾,过铝饱和型,属于钙碱性系列;具有轻稀土富集,重稀土分馏明显,其成因应该是部分陆壳熔融物质。晚志留-早泥盆纪序列侵入岩体具有轻稀土富集,重稀土亏损,轻重稀土分馏明显等特征,其成因是部分陆壳熔融。经岩石化学特征、微量、稀土元素地球化学特征研究以及岩体成因类型图解判别,得知奥陶纪侵入序列岩体均为S型花岗岩,晚志留-早泥盆纪侵入序列岩体为I-S型花岗岩;研究区震旦纪构造运动(拉张)使蒙古-阿尔泰洋褶皱、回返,最后关闭奥陶纪古亚洲洋向西伯利亚板块俯冲形成喀纳斯一带东锡勒克组中酸性火山岩;泥盆纪是板块俯冲-碰撞造山的主要时期,最后使阿尔泰陆缘活动带固结成新陆壳,进入陆内发展阶段。
[Abstract]:The study area is located on the north side of Erzis fault, northwest for the national boundaries.The magmatic activity in the study area is stronger and the rock types are complex. More geological work has been done on it, but less on the intrusive rocks in the western part of the Altai orogenic belt.By means of isotopic geochronology, petrology, geochemistry and field geological observation, the magmatic sequence of intrusive rocks in Chonghur area, western section of Altai orogenic belt, Xinjiang, has been studied in this paper.The study of petrogenesis and tectonic environment provides important basis.The following conclusions have been obtained: based on the results of the 1: 50 000 regional survey in the study area, four rock masses were selected, and the intrusive sequence was determined according to the route information, profile information and zircon U-Pb chronology data.Petrogenetic types and tectonic setting.The magma sequences of intrusive rocks in the study area are divided into Ordovician intrusion sequence and late Silurian early Devonian intrusion sequence by U-Pb dating analysis.Its LA-ICP-MS age is 473.3 卤2.9Mafor granitic granites, 469.8 卤2.9Mafor biotite granites and 455.3 卤3.1Ma.The granitic diorite is 420.6 卤3.0Ma and 414.8 卤2.6 Ma.The Ordovician series intrusive rock body has the same geochemical characteristics, high silicon, high alkali, high potassium, supersaluminous saturation type, belong to calc-alkaline series, it has light rare earth enrichment, heavy rare earth fractionation is obvious, its origin should be part of continental crust melt material.The late Silurian and early Devonian intrusive rocks are characterized by the enrichment of LREE, the depletion of heavy REE and the obvious fractionation of LREE, which is caused by partial continental crust melting.Based on the petrochemical characteristics, trace and rare earth element geochemical characteristics and diagrammatic discrimination of the genetic types of the intrusive rocks, it is concluded that the Ordovician intrusive sequence is S-type granite, and the late Silurian early Devonian intrusive sequence is I-S type granite.The Sinian tectonic movement (extension) made the Mongolian-Altai ocean fold return and finally closed the Ordovician Paleo-Asian Ocean subducting toward the Siberian plate to form intermediate-acid volcanic rocks of the East Sirake formation in Kanas area.Devonian was the main period of plate subduction-collision orogeny and finally consolidated the active belt of Altai continental margin into a new continental crust and entered the stage of intracontinental development.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P542;P588.12

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