新疆西准噶尔成矿带晚古生代花岗岩类岩石学特征及构造意义

发布时间：2018-04-19 20:58

本文选题：西准噶尔成矿带 + 晚古生代　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：新疆北部萨吾尔山以南、准噶尔盆地西北缘的西准噶尔地区(即“西准”),位于西伯利亚、哈萨克斯坦和塔里木板块的拼合处,属于哈萨克斯坦古板块北部增生边缘;为中亚造山带夹持在天山断裂系统与额尔齐斯断裂之间的一个特殊的北东向地块,发育以达拉布特断裂为代表的NE向左行走滑断裂构造体系,有别于中亚造山带西部NW向右行走滑的艾比湖断裂和西准噶尔以北近东西向左行走滑的额尔齐斯走滑断裂。西准地区地质构造比较复杂,主体构造为NE-NEE构造走向,主要为压性兼扭性结构面,具有NE向的“多字”型走滑断裂构造体系的特点,并明显地控制着区内花岗岩侵入体的分布;同时发育多个方向的褶皱和断裂。大规模的走滑运动可能引起块体的构造旋转。西准噶尔地区是中亚造山带西部重要的构造-岩浆-成矿带。本文对西准地区构造变形、演化与岩浆活动的相互关系做了一些研究工作;采集了西准噶尔成矿带达拉布特断裂西北侧的庙尔沟-别鲁阿嘎希及其附近地区11个岩体共33个花岗岩类样品,进行了岩相学、岩石地球化学与同位素示踪等研究,厘定了该地区晚古生代岩浆活动的特点与大地构造环境。研究表明,西准噶尔构造变形非常强烈,尤其南北向的挤压和北东向的走滑非常明显;区内庙尔沟岩体和阿克巴斯套岩体均发生了逆时针旋转构造;哈图地区晚石炭世花岗岩类主要为后碰撞伸展构造环境A型花岗岩类,别鲁阿嘎希等地区存在洋内俯冲与岛弧环境的埃达克岩,表明晚古生代西准噶尔地区构造环境时空变化的复杂性。该地区花岗岩类具有较高的εNd(t)值(+4.62-+7.53)、εSr(t)值为( 57.61-+18.21),具有中亚造山带花岗岩类的基本特征,为古生代增生的新生陆壳,其源区与亏损地幔组分具有亲缘关系;花岗岩类206Pb/204Pb比值为18.2776-19.1677、207Pb/204Pb比值为15.5260-15.5796、208Pb/204Pb比值为38.2080-39.0821,为造山带花岗岩类,与天山、阿尔泰山和巴尔喀什成矿带花岗岩类近似。根据地质构造的关系,西准噶尔与巴尔喀什可能是中亚造山带西段一个连续的东西向构造-岩浆活动成矿带。
[Abstract]:The West Junggar region, south of Sawuer Mountains in northern Xinjiang and the northwest margin of Junggar Basin, is located in Siberia, where Kazakhstan and Tarim plates join together, and belong to the northern accretive margin of the ancient Kazakstan plate. As a special NE block between Tianshan fault system and Erzis fault, the central Asian orogenic belt developed NE trending strike-slip fault system represented by Dalabut fault. Different from the west of the Central Asian orogenic belt, the Ebinur fault is different from the NW strike slip in the west of Central Asia and the Erzis strike-slip fault north of the west Junggar to the east to the west. The geological structure in Xizhong area is quite complex, the main structure is NE-NEE structural strike, which is mainly compressional and torsional structural plane. It has the characteristics of NE direction "multi-character" type strike-slip fault system, and obviously controls the distribution of granite intrusion in the area. At the same time, multiple directions of folds and faults are developed. Large-scale strike-slip motion may cause tectonic rotation of blocks. The West Junggar area is an important tectonic-magma-metallogenic belt in the western part of the Central Asian orogenic belt. In this paper, the relationship between tectonic deformation, evolution and magmatic activity in Xizhong area is studied. A total of 33 granitic samples were collected from the Miaoergou-Beluagaxi and its adjacent areas in the northwestern side of the Darabut fault in the West Junggar metallogenic belt. Petrographic, petrogeochemical and isotopic tracer studies have been carried out. The characteristics and tectonic environment of late Paleozoic magmatism in this area are determined. The results show that the deformation of the West Junggar structure is very strong, especially the compression in the north-south direction and the strike slip in the north-east direction, the Miaoergou rock body and the Akbasset rock body in the area have been rotated counterclockwise; The late Carboniferous granitoids are mainly A-type granitoids in the post-collisional extensional tectonic environment in the Hattu area, and the adakite in the Beilu Agahi area is characterized by intraoceanic subduction and island arc environment. It indicates the complexity of spatiotemporal variation of tectonic environment in the West Junggar area of late Paleozoic. The granitoids in this area have higher 蔚 Ndndnt values (4.62-7.53) and (57.61-18.21), which have the basic characteristics of granitic type in the Central Asian orogenic belt, and belong to the Cenozoic continental crust of Paleozoic accretion, and the source region is related to the depleted mantle component. The 206Pb/204Pb ratio of granitoids is 18.2776-19.1677207Pb/204Pb and the ratio of 15.5260-15.5796208Pb/204Pb is 38.2080-39.0821, which is the granitic type of orogenic belt, which is similar to the granitoids of Tianshan, Altaishan and Balkash metallogenic belts. According to the relationship of geological structure, West Junggar and Balkesh may be a continuous east-west tectonic-magmatic metallogenic belt in the western segment of the Central Asian orogenic belt.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.121;P612

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