青海五龙沟金矿床地质特征与成因研究

发布时间：2018-05-06 01:35

本文选题：青海 + 五龙沟　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：五龙沟金矿大地构造位置位于东昆仑中带,昆北与昆中断裂之间。矿区地层主要以下元古界金水口群和上元古界青白口系地层为主,矿区内构造十分发育,矿体严格受控于北西向韧性剪切带内及旁侧北西-北北西向脆性断裂。矿石类型主要为蚀变岩型金矿石,有少量石英脉型金矿石,金与毒砂、辉(铁)锑矿、黄铁矿关系密切,围岩蚀变主要以硅化、绢云母化、黄铁矿化、毒砂化为主。对岩(矿)石的微量元素进行R型聚类和因子分析,结果显示Au,Sb和As关系密切。R型聚类分析结果显示Au元素和As元素、Sb元素之间呈显著正相关,其相关系数分别为0.905和0.62。因子分析结果表明,毒砂、辉(铁)锑矿化阶段是主要成矿阶段。所以,含有的As元素和Sb元素的毒砂、辉(铁)锑矿和As元素含量较高的黄铁矿可以作为野外找矿指示标志矿物。矿区内主要出露中酸性岩浆岩,研究后认为闪长质岩浆岩与成矿有直接的关系,花岗质岩浆岩与金矿没有明显关系。闪长质岩浆岩为印支期侵入的结果,具有I型花岗岩特征,形成于火山弧的挤压构造环境,与金矿化关系密切。而花岗质岩浆岩集中于晚加里东时期发生侵入活动,具有A型花岗岩特征,形成于加里东后造山作用的碰撞构造环境,与金矿化没有密切关系。硫、铅同位素研究表明,成矿物质主要来自于幔源,并混入部分壳源物质,说明其主要来自于深源,后在上升过程中萃取了地层矿物质。成矿具体过程:晚加里东时期,洋壳向北俯冲闭合,沿俯冲碰撞带形成一系列大型逆冲型韧性剪切带,使得成矿流体活化。在华力西-印支早期,石炭纪开始出现的特提斯小洋盆向北俯冲,深熔作用发生,熔融岩浆携带流体、成矿物质上升侵位。晚印支期进入造山活动晚期,地壳抬升、加厚,岩石圈发生拆沉、减薄,幔源岩浆底侵、壳-幔混合作用强烈,偏中性的岩浆携带成矿流体及成矿物质发生迁移,萃取围岩中大量成矿物质,在上升侵位过程中沿韧性剪切带脆性断裂带处有物化条件的突变,沉淀成矿,后期在断层泥又有金的次生富集。经过研究对比,综合分析五龙沟金矿床在大地构造环境、成矿地质条件、成矿物质条件方面与Groves(1998)提出的造山型金矿类似,因此认定五龙沟金矿床为造山型构造蚀变岩亚型金矿床。
[Abstract]:The tectonic location of the Wulonggou gold deposit is located in the middle zone of East Kunlun, between the north of Kunlun and the fault of the middle of Kunlun. The strata of the mining area are mainly composed of the Proterozoic Jinshuikou Group and the Upper Proterozoic Qingbakou system. The ore bodies are strictly controlled by the NW ductile shear zone and the NNW trending brittle faults. The ore type is mainly altered rock type gold ore, there are a small amount of quartz vein type gold ore, gold and arsenopyrite, (iron) antimony ore, pyrite is closely related, the main alteration of surrounding rock is silicification, sericite, pyrite and arsenopyrite. The results of R cluster and factor analysis of trace elements in rock (ore) rocks show that there is a significant positive correlation between au element and as element Sb element, and the correlation coefficient is 0.905 and 0.62.The results show that there is a significant positive correlation between au element and as element Sb element. Factor analysis results show that arsenopyrite and iron (iron) antimony mineralization stage is the main metallogenic stage. Therefore, arsenopyrite, pyrite with high content of as and SB and pyrite with high content of as and SB can be used as indicator minerals for prospecting in the field. It is considered that diorite magma is directly related to mineralization, while granitic magmatic rock has no obvious relation with gold deposit. Diorite magmatic rocks are the result of Indosinian intrusions and have the characteristics of I-type granite formed in the compressional tectonic environment of volcanic arc and are closely related to gold mineralization. The granitic magmatic rocks are mainly intrusive during the late Caledonian period and have the characteristics of A-type granites formed in the collisional tectonic environment of post-Caledonian orogeny and have no close relationship with gold mineralization. The sulfur and lead isotopic studies show that the ore-forming materials are mainly derived from mantle source and mixed with some crustal materials, indicating that they are mainly derived from deep sources and then extracted during the rising process. During the late Caledonian period, the oceanic crust subducted northward and closed, forming a series of large thrust-type ductile shear zones along the subduction collision zone, which enabled the ore-forming fluid to be activated. In the early Varissian-Indosinian period, the Tethys small ocean basin began to appear in the Carboniferous and subducted northward. The melting-magma carried fluid and the ore-forming material was emplaced. In the late Indosinian period, the late Indosinian period entered the late orogenic period, the crust uplifted, thickened, the lithosphere desunk, thinned, mantle-derived magma undercut, the crust-mantle mixing was strong, and the neutral magma carried the ore-forming fluid and the ore-forming material for migration. A large number of ore-forming materials are extracted from the surrounding rock. In the process of rising emplacement, there are sudden changes in physicochemical conditions along the brittle fault zone along the ductile shear zone, precipitation and mineralization, and gold enrichment in the fault gouge at the later stage. Through research and comparison, it is analyzed that the gold deposit of Wulonggou is similar to the orogenic gold deposit proposed by Grovess1998in terms of geotectonic environment, ore-forming geological conditions and ore-forming mineral conditions. Therefore, Wulonggou gold deposit is considered as orogenic tectonic alteration rock subtype gold deposit.
【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】：P618.51

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