湘西花垣MVT型铅锌矿集区成矿作用研究

发布时间：2018-04-16 17:28

本文选题：MVT + 成矿作用　；参考：《成都理工大学》2017年博士论文

【摘要】：花垣铅锌矿床是湘西-鄂西铅锌成矿带中最具代表性的超大型铅锌矿床,该矿床远景储量超过1000万吨,铅锌品位高,矿床规模大、具有很高的经济价值和研究价值。本文在全面介绍矿床区域地质、矿集区矿床地质特征基础上,系统分析了矿床微量元素、稀土元素地球化学特征,S、Pb、Sr、C、H、O同位素地球化学特征及流体包裹体特征,利用多种定年方法对矿床进行了精确定年,从成矿物质来源、成矿流体来源以及地层、构造、有机质这三种因素与成矿的关系等方面讨论了花垣铅锌矿床的矿床成因,在此理论基础上,进而建立了矿床成因模式,最后讨论了湘西-鄂西成矿域的低温成矿作用。花垣矿田铅锌矿床闪锌矿和方铅矿为与盆地卤水有关的沉积型热液改造成因。硫化物中含分散元素,闪锌矿中镉元素含量最为富集,为MVT型铅锌矿床典型特征。矿石矿物与围岩稀土元素组成具有较大的差异性,前者稀土元素总量明显低于后者,含矿层并不是成矿物质的主要来源。铅锌矿石中硫化物的还原硫主要来自地层中海相硫酸盐的还原。铅同位素可能主要来源于奥陶系—寒武系地层。成矿流体的锶同位素比值高于赋矿地层,成矿流体流经了清虚洞组下伏地层,并与其中具有高锶同位素比值的泥岩地层牛蹄塘组进行了水岩反应及同位素交换。主矿化期的方解石和闪锌矿系统的C、H、O同位素研究结果显示花垣地区团结、李梅、土地坪、蜂塘和大石沟等铅锌矿床中主成矿期脉石矿物方解石的13C、18O同位素依次表现出逐渐降低的特征,铅锌矿床成矿流体中的C主要来源于海相碳酸盐岩的溶解作用,围岩具沉积成因海相碳酸盐岩特征。成矿流体的主要来源是建造水和大气降水。花垣地区铅锌矿床成矿流体是具有低温度、中高盐度、高密度,以钠和钙氯化物为主的热卤水性质的含矿热水溶液。成矿流体均一温度具有由北而南降低的趋势,显示了成矿流体的运移方向。流体包裹体气相中发育CO2、CH4和H2。闪锌矿、方铅矿等矿石矿物与方解石、萤石等脉石矿物应属同一富成矿元素的成矿流体在同一成矿期次相同条件下沉淀的产物。花垣矿集区李梅铅锌矿床成矿地质时代为中奥陶世,狮子山铅锌矿床成矿地质时代为早泥盆世,方解石可能形成于早奥陶世。多期性的成矿作用发生于加里东期,成矿时代晚于赋矿围岩。该地区铅锌矿床的分布明显受岩性、地层、岩相的控制。成矿模式分为成矿流体形成阶段和成矿热液运移富集阶段。第一个阶段发生于盆地埋藏和构造挤压时期,深部流体与地层水、大气降水混合发生广泛的水/岩反应,形成富含铅锌等金属元素的成矿流体;第二个阶段发生于伸展构造环境,发生大规模迁移的成矿流体在台地边缘等有利部位,发生热化学硫酸盐还原反应,沉淀富集成矿。湘西-鄂西地区成矿流体是低温度、中高盐度、高密度,以钠和钙氯化物为主的热卤水,该区铅锌矿床为大范围低温流体成矿作用的结果,可能与华南地区发生的拉张断陷导致的盆地流体大规模流动有关。
[Abstract]:Huayuan Pb Zn deposit is a deposit in Western Hubei Xiangxi superlarge lead-zinc lead-zinc metallogenic belt in the most representative, the deposit reserves of more than 10 million tons of lead and zinc deposits are large in scale, high grade, has very high economic value and research value. This paper introduced in detail the regional geology, ore deposit geological characteristics on the basis of system analysis, trace element deposit, geochemical characteristics of rare earth elements, S, Pb, Sr, C, H, O isotope geochemistry and fluid inclusion characteristics, using a variety of dating methods were accurate dating of deposits, from mineral sources, sources of ore-forming fluids and the formation, structure, organic matter these three factors and the relationship between the uranium mineralization and discussed the genesis of lead-zinc deposits in Huayuan, on the basis of this theory, and then establish the metallogenic model, finally discussed the low temperature in the Xiangxi West Hubei metallogenic domain of mineralization. Huayuan orefield Lead-zinc deposit in sphalerite and galena as sedimentary hydrothermal transformation causes related to basin brine. Sulfide containing dispersed elements, the contents of cadmium in the enrichment of sphalerite, the typical feature of MVT type lead-zinc deposit. The ore minerals and rock composition of rare earth elements has great difference, the total amount of rare earth elements was significantly lower than the latter, the main source of the ore bearing not of ore materials. The reduction of sulfur sulfide in lead-zinc ore mainly from strata marine sulfate. The lead isotope can be mainly attributed to the Ordovician - Cambrian strata. The ore-forming fluid is higher than the ratio of Sr isotopes and ore formation, metallogenic fluid flows through the strata Qingxudong formation, mudstone formation of Niutitang Formation and has high strontium isotope ratios and the reaction and the isotopic water rock exchange. The main mineralization period of calcite and sphalerite system C, H, O isotope Research results show that Huayuan united, Li Mei, land Ping, bee pond and Dashigou lead-zinc deposits in the main mineralization stage of calcite 13C, 18O isotope are characterized by decreased the dissolution of ore-forming fluids in C mainly from marine carbonate rock, with sedimentary genesis of marine carbonate rocks the main feature. The source of the ore-forming fluid is built and meteoric water. The ore-forming fluid lead-zinc deposit in Huayuan area is a low temperature, high salinity, high density, hot brine with sodium and calcium chloride in the ore bearing hydrothermal solution. The ore-forming fluid with uniform temperature decreased from north to south, shows the migration the direction of the ore-forming fluid. The fluid inclusions in the development phase CO2, CH4 and H2. in sphalerite, galena ore minerals and gangue minerals such as calcite, fluorite should belong to the same rich metallogenic element mineralization The product of fluid precipitation in the same metallogenic period under the same conditions. Huayuan ore district Li Mei lead-zinc deposit metallogenic age of Middle Ordovician, the lion mountain lead-zinc deposit metallogenic geological age is early Devonian, calcite may be formed in the early Ordovician period. The mineralization occurred in Caledonian mineralization the times later than the host rock. The distribution of lead-zinc deposits in this area are significantly affected by lithology, stratigraphy, facies control. The metallogenic model is divided into formation stage of ore-forming fluids and ore-forming hydrothermal migration and enrichment stages. The first stage occurred in the burial and tectonic compressional period, deep fluid and formation water, meteoric water mixing occurs widely in water / rock reaction, the formation of ore-forming fluids rich in lead and zinc and other metal elements; the second stage occurred in the extensional tectonic environment, large-scale migration of ore-forming fluids in platform margin, favorable location, occurrence of thermo chemical sulfate Salt reduction reaction, precipitation and enrichment of mineralization. Xiangxi - West Hubei metallogenic fluid is low temperature, high salinity, high density, hot brine with sodium and calcium chloride. The lead-zinc deposit in this area for a wide range of cryogenic fluid mineralization results may be associated with the large-scale flow of basin fluid occurred in Southern China caused tension fault depression.

【学位授予单位】：成都理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P618.4

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