云南元江岔河铜矿床地质地球化学特征及成因探讨

发布时间：2018-06-07 23:03

  本文选题：岔河铜矿床 + 成矿物质来源　； 参考：《成都理工大学》2015年硕士论文

【摘要】：扬子地块西南缘是我国重要的铜、铁多金属矿集区,产有大红山、拉拉等大型、特大型铜铁多金属矿床,受到国内外学者的关注。岔河铜矿床为该区域内一个典型的铜多金属矿床,前人对该矿床的研究较少,研究程度不高,制约了对该矿床成矿规律的认识,进而影响了找矿。为探讨岔河铜矿床的地球化学特征和矿床成因,在中国地质调查局工作项目(编号:12120113095500)、中国核工业地质局重点科研项目(编号:201148)的支持下,在收集大量资料、系统的总结和分析前人研究成果的基础上,论文结合野外工作和室内分析测试等工作,以矿床内围岩、矿石以及热液石英脉、方解石脉等特征矿物为研究对象,通过微量元素地球化学、同位素地球化学、流体地球化学、岩石学、矿床学等方法对岔河铜矿床进行了深入研究,探索了矿床物质来源、流体性质及来源、矿床成因等问题。具体取得的成果如下:(1)根据围岩的常量元素和稀土元素特征,对变质围岩进行了原岩恢复,结果表明,岔河铜矿床片岩类和石英岩的原岩为沉积岩,围岩属于大陆边缘杂砂岩,形成环境可能为被动大陆边缘。(2)岔河铜矿床黄铜矿与黄铁矿硫同位素组成呈较大负值与沉积硫同位素组成相似,说明矿石硫源与含矿地层有关。黄铜矿铅同位素组成变化较大,具有放射性异常铅(铀型铅和钍型铅)的特征,在构造环境演化图解上显示上地壳来源。微量元素及稀土元素研究表明,成矿物质来源于围岩,成矿流体具有不同来源。(3)岔河铜矿床中两期方解石碳同位素平均值处于岩浆碳(-5‰~-8‰)与海相沉积碳(-1‰~+2‰)之间,说明碳的来源可能是岩浆碳和海相碳酸盐共同提供的结果,暗示成矿流体可能由岩浆水和浅部流体组成,流体中的氧同位素受到大气降水影响而呈负漂移。(4)岔河铜矿床成矿期石英流体包裹体研究显示,成矿流体属中-低温、中等盐度、低密度的流体。结合碳氧同位素、石英流体包裹体成分及拉曼光谱分析认为,成矿流体为岩浆水、变质水和大气降水的混合流体。(5)岔河铜矿床成因:早元古代期间,本区域存在一系列的边缘裂谷型优地槽,并沉积了一套中-浅变质程度的赋钠质和金属矿质的火山沉积岩系,中元古代末格林威尔运动,使区域地层发生大规模变质、变形,并存在岩体侵入事件,从而提供了大规模的热动力,地层中以不同形式存在的水活化,汇聚成赋有较高溶解能力的变质热液,与岩浆水和大气降水混合。混合流体在运移过程中,不断的萃取地层中的成矿元素,使成矿元素活化、运移,当流体运移到适宜的环境时,由于压力的降低、物理化学条件的改变,流体中的成矿元素沉淀并富集成矿。
[Abstract]:The southwestern margin of the Yangtze block is an important copper and iron polymetallic ore concentration area in China, with large and super large copper and iron polymetallic deposits such as Dahongshan, Lala and so on, which have attracted the attention of scholars at home and abroad. The Chahe copper deposit is a typical copper polymetallic deposit in the region. The previous researches on the deposit are less and the degree of study is not high, which restricts the understanding of the metallogenic law of the deposit and further affects the prospecting. In order to study the geochemical characteristics and genesis of the Chahe copper deposit, with the support of the project of China Geological Survey (No. 12120113095500) and the key scientific research project of China Bureau of Nuclear Industry and Geology (No.: 201148), a large amount of data were collected. On the basis of summarizing and analyzing the previous research results systematically, this paper combines the field work and laboratory analysis and test work, taking the characteristic minerals such as the surrounding rock, ore, hydrothermal quartz vein, calcite vein and so on in the deposit as the research object. By means of trace element geochemistry, isotope geochemistry, fluid geochemistry, petrology and mineralogy, the Chahe copper deposit is deeply studied, and the source of material, fluid property and origin of deposit are explored. The results obtained are as follows: (1) according to the characteristics of major elements and rare earth elements of surrounding rock, the original rock of metamorphic rock is restored. The results show that the original rock of schist and quartzite of Chahe copper deposit is sedimentary rock, and the surrounding rock belongs to continental margin complex sandstone. The formation environment may be passive continental margin.) the sulfur isotopic compositions of chalcopyrite and pyrite are negative and similar to those of sedimentary sulfur isotopes, indicating that the ore sulfur source is related to ore-bearing strata. The lead isotopic composition of chalcopyrite varies greatly and has the characteristics of radioactive anomalous lead (uranium-type lead and thorium type lead), showing the origin of the upper crust in the diagram of tectonic environment evolution. The study of trace elements and rare earth elements shows that the ore-forming materials come from surrounding rock. The average carbon isotopic values of calcite in the two periods are between magmatic carbon (5 鈥，

本文编号：1993181