西秦岭大桥金矿地质特征及构造控矿研究

发布时间：2018-06-23 15:41

本文选题：西秦岭 + 大桥金矿　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：大桥金矿床位于西秦岭中部裂陷槽,岷县~宕昌~两当和舟曲~成县~徽县大断裂之间,三叠系下部建造层的下岩性段(Ta-1)为主要的金矿体赋存部位,其主要岩性为硅化角砾岩。矿体以层状、似层状、透镜状、鞍状产出。矿石矿物以黄铁矿、白铁矿和毒砂为主,脉石矿物以石英为主。围岩蚀变主要为黄铁矿化、硅化、褐铁矿化。在对区域地质及矿区地质特征研究的基础上,本文对大桥金矿岩(矿)石的主微量元素、矿区宏观构造及显微构造进行了系统的研究,取得以下5点认识:(1)结合硅化角砾岩地质特征和其主微量元素特征分析认为:硅化角砾岩分布受矿区NE向断层控制,断裂为成矿热液运移通道;硅化角砾岩具有比较明显的硅质胶结特征,岩浆热液提供了SiO_2,硅化角砾岩为破碎角砾经过硅化胶结作用形成。(2)岩(矿)石的主微量元素特征可表明:地层为金的主要来源,具有金的富集特征;岩浆与围岩存在着物质交换,提供SiO_2等物质。(3)大桥金矿区金矿体严格受构造控制,断裂为导矿构造,褶皱滑脱部位为容矿构造。褶皱可以分为两期:第一期为区域上形成的以石炭系为核部的背斜,以及其同期形成的轴向NE向展布的次级褶皱;第二期为横弯褶皱作用造成的平卧褶皱。其中第二期褶皱为主要的容矿构造。(4)大桥金矿区主应力为NE~SW向压应力;区内构造经历了韧性到韧-脆性再到脆性的构造变形。(5)大桥金矿矿床属于沉积~改造型金矿床。矿体主要的成矿物质来源为地层金,二叠系以前因风化剥蚀作用而形成的陆源碎屑物对金起到了早期的富集作用。晚三叠世的陆内造山构造运动及岩浆活动造成地层金活化、运移,并且在构造的有利部位沉淀,形成金矿床。
[Abstract]:The bridge gold deposit is located in the rift trough in the central part of the West Qinling Mountains, between Minxian ~ Dangchang ~ Liangdang and Zhouqu ~ Chengxian ~ Huixian big faults. The lower lithologic segment (Ta-1) of the lower Triassic formation is the main place of occurrence of the gold orebody, the main lithology of which is silicified breccia. The orebodies are stratiform, layered, lenticular, and saddle-shaped. Ore minerals are mainly pyrite, albite and arsenopyrite, and gangue minerals are quartz. The main alteration of surrounding rock is pyrite, silicification and limonite. On the basis of the study of regional geology and geological characteristics of mining area, this paper systematically studies the main and trace elements, macroscopic structure and microstructure of the rock (ore) stone of the Daqiao gold mine. It is concluded that the distribution of silicated breccia is controlled by NE fault and the fault is the channel of hydrothermal migration of ore-forming; (1) according to the geological characteristics of silicified breccia and its main trace element characteristics, the distribution of silicated breccia is controlled by NE fault; Silicated breccia has obvious siliceous cementation characteristics, magmatic hydrothermal solution provides SiOS-2, silicified breccia is formed by silicification and cementation of broken breccia. (2) the main trace element characteristics of rock (ore) stone indicate that the formation is the main source of gold. It is characterized by gold enrichment and material exchange between magma and surrounding rock to provide SiOShi 2 and other materials. (3) the gold ore body in the Daqiao gold deposit area is strictly controlled by the structure, the fault is a ore-conducting structure, and the fold and slip part is a ore-bearing structure. The fold can be divided into two stages: the first stage is the anticline with Carboniferous as the core, and the secondary fold formed at the same time in the axial NE direction, and the second stage is the horizontal fold caused by the transverse bend fold. The second stage fold is the main ore-bearing structure. (4) the main stress of the Daqiao gold deposit is NE-SW compressive stress, and the structure in the area has experienced structural deformation from ductile to brittleness. (5) the Daqiao gold deposit belongs to sedimentary ~ reformed type gold deposit. The main source of ore-forming material is the formation gold, and the continental clastic materials formed by weathering and denudation in the Permian have an early enrichment effect on the gold. The late Triassic intracontinental orogenic tectonic movement and magmatic activity resulted in the activation and migration of gold in the strata and the deposition of gold deposits in favorable parts of the structure.
【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】：2017
【分类号】：P618.51

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