藏南金锑多金属成矿带载金矿物特征及其指示意义

发布时间：2019-04-02 03:29

【摘要】：藏南金锑多金属成矿带是近十几年来国内外广大学者研究与关注的热点地区。本论文以该成矿带代表性矿床查拉普金矿、马扎拉金锑矿和邦布金矿为研究对象,在野外地质调查的基础上,通过对载金矿物手标本和电子显微镜下的详细观察,结合电子探针分析(EMPA),对三个矿床的载金矿物类型和金的赋存状态进行了研究,并进一步对成矿作用演化和矿床类型进行了探讨。查拉普金矿床的金主要以不可见金的形式赋存于黄铁矿和毒砂中。黄铁矿可以分为沉积成岩期黄铁矿Py1,热液期早阶段黄铁矿Py2和热液期主阶段黄铁矿Py3。Py1多呈草莓状、胶状结构,其中w(Au)最高,显示了金在沉积成岩期的大量富集。Py2与Py1元素组成相似,显示了一定的继承演化关系。Py3是含砷黄铁矿,与毒砂共生,是最重要的载金矿物。Au在Py1和大部分Py2中主要以纳米级自然金(Au0)的形式存在。而在Py3中,Au主要以固溶体(Au+)的形式存在。其上述特点符合大多数卡林型金矿的特征。马扎拉金锑矿床的金主要以可见的自然金和不可见金两种形式存在,自然金主要以裂隙金、包裹金和粒间金三种形式赋存于辉锑矿和石英中。不可见金主要赋存于黄铁矿中。黄铁矿可以分为沉积成岩期黄铁矿Py1,热液期含砷黄铁矿Py2和Py3。Py1呈草莓状结构,w(Au)较高,显示了金在沉积成岩期的初步富集。Py2与Py1相比w(As)明显提高,是不可见金最主要的载金矿物,显示了热液早期的流体富含Au、As。部分Py2由于造山作用挤压而形成破裂状Py3,这个过程释放了部分的Au、As进入到变质流体。不可见金在Py1中主要以纳米级自然金(Au0)的形式存在,在Py2和Py3中主要以固溶体金(Au+)和纳米级自然金(Au0)两种形式存在。其上述特点符合大多数造山型金矿的特征。邦布金矿床金的主要赋存形式为可见的自然金,其主要以裂隙金、包裹金和粒间金三种形式赋存于石英和黄铁矿中。不可见金含量相对较低,主要赋存于黄铁矿和毒砂中。黄铁矿可以分为自形粗粒黄铁矿Py1、半自形细粒黄铁矿Py2和自形细粒黄铁矿集合体Py3,其中以Py1的碎裂状核部和Py2含金性最好。不可见金在Py1的碎裂状核部和Py2中主要以纳米级自然金(Au0)的形式存在。其上述特点符合大多数造山型金矿的特征。
[Abstract]:The gold-antimony polymetallic metallogenic belt in southern Tibet is a hot area studied and paid attention to by scholars at home and abroad in recent ten years. In this paper, the Charap gold deposit, Mazara gold antimony deposit and Bangbu gold deposit in this metallogenic belt are studied. On the basis of the geological investigation in the field, the hand specimens of the gold-carrying mineral and the electron microscope are observed in detail. The types of gold-bearing minerals and the occurrence of gold in the three deposits were studied by means of electron probe analysis (EMPA), and the evolution of mineralization and the types of deposits were further discussed. The gold in the Charap gold deposit is mainly in the form of invisible gold in pyrite and arsenopyrite. Pyrite can be divided into Py1, pyrite in sedimentary diagenetic period, pyrite Py2 in early hydrothermal period and pyrite Py3.Py1 in main hydrothermal stage in strawberry and gelatinous structure, among which w (Au) is the highest. Py2 is similar to Py1. Py3 is arsenic-bearing pyrite, which is symbiotic with arsenopyrite, which is similar to pyrite in sedimentary diagenetic period, and the composition of Py2 is similar to that of Py2 in sedimentary diagenetic period, indicating that Py3 is arsenopyrite. Au is the most important gold-carrying mineral. Au mainly exists in the form of nano-scale natural gold (Au0) in Py1 and most of Py2. In Py3, Au mainly exists in the form of solid solution (Au). The above-mentioned characteristics accord with the characteristics of most Carlin type gold deposits. The gold in Mazara gold-antimony deposit is mainly in the form of visible natural gold and invisible gold, and the natural gold mainly occurs in antimonite and quartz in the form of fissured gold, encapsulated gold and intergranular gold. Invisible gold occurs mainly in pyrite. Pyrite can be divided into sedimentary diagenetic period, pyrite, Py1, hydrothermal period, arsenic-bearing pyrite Py2 and Py3.Py1 have higher strawberry structure, w (Au), indicating the initial enrichment of gold in sedimentary diagenetic period. Py2 is obviously higher than Py1 in w (As). It is the main gold-carrying mineral of invisible gold, which shows that the early hydrothermal fluids are rich in Au,As.. The process of forming ruptured Py3, due to orogenic extrusion of part of Py2 releases part of Au,As into metamorphic fluid. Invisible gold mainly exists in the form of nanometer natural gold (Au0) in Py1, while in Py2 and Py3 it is mainly in the form of solid solution gold (Au) and nanometer natural gold (Au0). The above-mentioned characteristics accord with the characteristics of most orogenic gold deposits. The main occurrence form of gold in Bangbu gold deposit is visible natural gold, which mainly occurs in quartz and pyrite in the form of fissured gold, encapsulated gold and intergranular gold. The content of invisible gold is relatively low and occurs mainly in pyrite and arsenopyrite. Pyrite can be divided into self-shaped coarse-grained pyrite Py1, semi-autogenous fine-grained pyrite Py2 and autogenous fine-grained pyrite aggregate Py3, among which the fragmentation of Py1 and the gold content of Py2 are the best. Invisible gold exists mainly in the form of nano-scale natural gold (Au0) in the fragmentation nucleus of Py1 and in Py2. The above-mentioned characteristics accord with the characteristics of most orogenic gold deposits.
【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】：P618.2

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