云南文山小平坝钨多金属矿区花岗岩及矽卡岩研究

发布时间：2018-05-04 14:46

本文选题：成矿花岗岩 + 矽卡岩　；参考：《昆明理工大学》2015年硕士论文

【摘要】：本文在详细的矿区地质调查及样品分析测试的基础上,应用现代矿床学、岩石学及地球化学等理论方法,对文山小平坝矿区矿床地质、成矿岩体及矽卡岩进行了综合分析研究,取得如下成果认识：矿区的成矿地质条件较好：在地层岩性组成方面,古生代浅海陆棚-滨海相碎屑岩-碳酸盐岩地层中W等成矿元素的初始富集可为成矿提供一定物质基础,寒武系地层中碳酸盐岩可为小平坝矽卡岩型W、Fe、Pb、Zn多金属矿床的形成提供有利岩性条件；在构造方面,矿区内NE和NW向断层、接触带裂隙等构造较发育,为含矿流体的运移、聚集和矿质沉淀提供了有利空间；在岩浆岩类型方面,矿区位于薄竹山燕山期复式中酸性岩体东缘,具备矽卡岩型W、Sn成矿的有利岩浆活动条件。矿区成矿岩体为薄竹山复式岩体第一期中-粗粒黑云二长花岗岩,其A/CNK大于1,属过铝质,富K2O、SiO2,σ平均为2.54,具高钾钙碱性。岩石中La、Zr、Pb、Rb、U、Th等LILE富集,Sr、Ba、Ti、Nb、Ta等不相容元素、HFSE相对亏损；稀土总量较高,轻重稀土分异较强,Eu显中等负异常。LA-ICP-MS锆石U-Pb同位素年龄集中在84-93Ma之间,与晚白垩世华南西部岩浆成矿带主成矿时代相当。构造环境判别研究显示,其为燕山晚期早阶段同碰撞构造环境下上地壳砂泥质沉积物局部熔融经结晶分异形成,属S型花岗岩。岩体中成矿元素含量较高,是矿区主要物质来源。区内矽卡岩主要在接触带、围岩裂隙、层间破碎带中发育。按位置及含矿性的不同,可分为含白钨矿矽卡岩或矿石、条带状矽卡岩和铅锌矿化矽卡岩三类。不同矽卡岩在矿物组成、结构构造及主量元素含量等方面均存在明显区别,但微量、稀土元素地球化学特征与矿区花岗岩有相似之处。岩石地球化学特征表明,成矿花岗岩侵入过程中,岩浆热液与碳酸盐岩(围岩)之间发生明显的物质交换,岩浆热液带来的Si、Fe、Al、REE和Co、V、Zn、Ni、W、Sn等亲铁-亲铜元素进入围岩,围岩中的Ca、Mg被活化进入热液体系。经双交代作用,形成含白钨矿矽卡岩或矿石、条带状矽卡岩和铅锌矿化矽卡岩。矽卡岩化过程中,还出现大离子亲石元素K、Sr、Rb、Pb、Ba、Cs和高场强元素Nb、Ta、Hf、Zr等随流体迁出。矽卡岩化强度主要受岩体控制,并与大气降水的入渗作用有关,远离岩体的围岩矽卡岩化程度较低,且受大气降水入渗作用较强。因此,本文认为,小平坝矿区为燕山晚期早阶段岩浆热液混合大气降水形成的典型矽卡岩型矿床。
[Abstract]:On the basis of detailed geological investigation and sample analysis and test of mining area, this paper makes a comprehensive analysis and study on the geology, ore-forming rock mass and skarn of Xiaopingba mine area in Wenshan by using modern ore deposit theory, petrology and geochemistry. The results are as follows: the ore-forming geological conditions of the mining area are good: in terms of stratigraphic lithologic composition, the initial enrichment of W and other metallogenic elements in the Paleozoic shallow-littoral clastic rock-carbonate strata can provide a certain material basis for mineralization. The carbonate rocks in Cambrian strata can provide favorable lithologic conditions for the formation of the small Pingba skarn type WnFeFePbPb-Zn polymetallic deposit, in terms of structure, NE and NW trending faults in the mining area, fractures in the contact zone and other structures are relatively developed, which are the migration of ore-bearing fluids. In terms of magmatic rock types, the ore area is located at the eastern edge of the complex intermediate-acid rock mass in the Bozhushan Yanshanian period, and has favorable magmatic activity conditions for skarn type WPS-Sn mineralization. The ore-forming body of the ore-forming area is a medium-coarse black cloud monzomorphic granite in the first phase of the Bozhushan complex rock mass. Its A/CNK is greater than 1, which is peraluminous, rich in K _ 2O _ 2O _ 2O _ 2O _ 2, 蟽 is 2.54, and has high potassium calc-alkaline. In the rocks, LILE is enriched with LILE, such as LILE, for example, LILE enrichment, the relative depletion of the incompatible elements, such as Srsr-BaBaTiTiNbTh, is relatively low, the total amount of rare earths is relatively high, and the EU shows moderate negative anomalies. The isotopic ages of LA-ICP-MS zircon U-Pb isotopes are concentrated in the range of 84-93Ma, and the isotopic ages of the zircon are mainly in the range of 84-93Ma. It is equivalent to the main metallogenic age of the magmatic metallogenic belt in the western part of South China in the late Cretaceous. The tectonic environment discriminant study shows that it belongs to S-type granite in the early stage of the late Yanshanian stage and the local melting of the sandy mud sediments in the upper crust is formed by crystallization differentiation under the same collision tectonic environment in the late Yanshanian period. The content of ore-forming elements in rock mass is high, which is the main material source in mining area. Skarn is mainly developed in contact zone, rock fissure and interlayer fracture zone. According to the location and ore-bearing property, there are three types of skarn, zonal skarn and lead-zinc mineralized skarn. There are obvious differences in mineral composition, structural structure and principal element content among different skarn rocks, but the geochemical characteristics of trace rare earth elements are similar to those of granites in the mining area. The petrogeochemical characteristics indicate that during the intrusive process of ore-forming granites, there is obvious material exchange between magmatic hydrothermal solution and carbonate rock (surrounding rock), and the iron-friendly and copper-friendly elements such as Si-FeFeAlREE and Co-VVZZZZZZNI-WWSn, which are brought by magmatic hydrothermal solution, enter into the surrounding rock. Caomg in surrounding rock is activated into hydrothermal system. Through double metasomatism, skarn or ore containing scheelite, zonal skarn and lead-zinc mineralized skarn are formed. In the process of skarn lithology, the large ion lithophile elements, such as K ~ (+) S _ (Sr) _ (Rb) ~ (B) ~ (B) ~ (B) ~ (B) ~ (B) ~ (1) ~ (3) ~ (-) ~ (2 +) ~ (3) ~ (2 +) The strength of skarn is mainly controlled by rock mass and is related to the infiltration of atmospheric precipitation. The skarn degree of surrounding rock is low and strongly influenced by atmospheric precipitation. Therefore, it is considered that Xiaopingba ore area is a typical skarn type deposit formed by magmatic hydrothermal mixed atmospheric precipitation in the late Yanshanian period.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.2

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