藏南洛扎断裂构造特征及其对矿产资源的控制

发布时间：2018-06-30 03:54

本文选题：洛扎断裂 + 藏南拆离系　；参考：《成都理工大学》2017年硕士论文

【摘要】：喜马拉雅造山带是世界上最年轻、最典型的造山带,是由70~50 Ma印度板块与亚洲大陆碰撞—汇聚作用产生的。自碰撞以来,喜马拉雅造山带地壳大幅度缩短,进入中新世,在地壳缩短增厚的同时,喜马拉雅造山带还发生了大幅度的伸展拆离运动,两者构成了复杂的演化过程,在藏南地区形成了复杂的地质构造。碰撞造山还引发了藏南地区锑、锑金、锑铅锌多金属矿床的成矿作用,该成矿带已被广泛认为是寻找锑金矿的有利地带。洛扎断裂位于冈底斯—喜马拉雅造山系中的喜马拉雅地块,在区域上与定日—岗巴断裂为同一断裂,是藏南拆离系的重要活动断裂,藏南地区主要的锑金矿床就分布在洛扎断裂附近。本文通过对数条横穿洛扎断裂的线路进行野外地质观测,看到了丰富的构造现象,将洛扎断裂带分为了主脆性断层、韧性断层及分支脆性断层,结合室内分析及前人研究成果,将洛扎断裂的应力演化划分为六期,分别为(1)古近纪NE-SW向挤压,表现为主脆性断层中的逆冲遗迹以及分布在断裂上盘的褶皱冲断带;(2)中新世近南北向拉张,引发淡色花岗岩侵入,韧性断层发生向北流动,并可见变质矿物定向排列;(3)中新世后NE-SW向挤压,中新世花岗岩中发育大量近直立劈理带,侏罗系日当组、陆热组的砂岩、板岩中发育X节理,并充填方解石脉;(4)中新世后NW-SE向挤压,中新世花岗岩体内发育节理及较缓劈理带;(5)中新世后NNW-SSE向挤压,中新世花岗岩体内发育剪节理、逆断层,侏罗系日当组、陆热组的砂岩、板岩中X节理中石英脉替换方解石脉;(6)第四纪近南北向拉张,主脆性断层正断活动,中新世花岗岩体内发育正断系统。通过对洛扎断裂应力演化的研究,再结合区域内矿床的成矿规律,推测洛扎断裂可能为成矿作用提供了容矿空间,并对成矿物质来源有一定影响,为驱动成矿流体循环提供了热能。
[Abstract]:The Himalayan orogenic belt is the youngest and most typical orogenic belt in the world. Since the collision, the crust of the Himalayan orogenic belt has been shortened by a large margin and entered the Miocene. At the same time the crustal shortening and thickening, the Himalayan orogenic belt has also undergone a large extensional detachment movement, which constitutes a complex evolution process. Complex geological structures were formed in southern Tibet. The collisional orogeny has also triggered the mineralization of antimony, gold and antimony lead zinc polymetallic deposits in southern Tibet, which has been widely regarded as a favorable zone for prospecting for antimony gold deposits. The Luoza fault is located in the Himalayan block in the Gangdis Himalayan orogenic system. It is the same fault as the Dingri-Gangba fault in the region and is an important active fault of the south Tibet detachment system. The main antimony and gold deposits in southern Tibet are located near the Luoza fault. In this paper, through the field geological observation of several lines crossing the Luoza fault, we can see rich structural phenomena. The Luoza fault zone is divided into main brittle fault, ductile fault and branched brittle fault, combined with laboratory analysis and previous research results. The stress evolution of the Luoza fault is divided into six stages, namely (1) Ne-SW compression in Paleogene, showing thrust traces in the main brittle faults and fold thrust belts distributed in the upper face of the fault, (2) extensional movement in the north and south direction of the Miocene, The pinkish granite intrusions, the ductile faults flow northward, and the metamorphic minerals are arranged in a directional manner. (3) after Miocene, Ne-SW compression, a large number of nearly vertical cleavage belts, Jurassic Ridang formation, continental heat formation sandstone are found in the Miocene granites. X joints developed in slate and filled with calcite veins; (4) NW-SE compression after Miocene, joints and gentle cleavage zones developed in Miocene granite; (5) compression in post-Miocene NNW-SSE direction, shear joints and reverse faults in Miocene granite. The sandstone of the Jurassic Ridang formation and the Luge formation in which the X joint quartz vein replaces the calcite vein in the slate; (6) the Quaternary near S N trending extensional, the main brittle fault is normal fault, and the Miocene granite body develops normal fault system. Based on the study of the stress evolution of the Luoza fault and the metallogenic regularity of the deposits in the region, it is inferred that the Luoza fault may provide the ore-bearing space for the mineralization, and have certain influence on the source of the ore-forming material. It provides heat energy for driving the circulation of ore-forming fluid.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P542;P613

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