柿竹园钨、锡多金属矿田成矿流体地球化学研究

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	柿竹园钨、锡多金属矿田成矿流体地球化学研究
其他题名	The Geochemistry of Ore-forming Fluid of Shizhuyuan W-Sn Polymetallic Orefield in Hunan Province,P.R.China
	武丽艳
	2009-05-25
学位授予单位	中国科学院地球化学研究所
学位授予地点	地球化学研究所
学位名称	博士
关键词	柿竹园矿田流体包裹体稀有气体同位素稳定同位素成矿流体
摘要	南岭地区是我国最重要的有色、稀有金属矿产资源产地，尤以钨、锡等金属的大规模爆发式成矿而闻名于世，已发现了一大批大型、超大型稀有和有色金属矿床。近年来的研究发现，这些矿床的形成很可能与华南地区中生代发生的大规模地壳拉张、岩石圈伸展减薄以及壳―幔相互作用的独特地质背景有关。本论文以与千里山花岗岩体密切相关的柿竹园钨锡钼铋铅锌矿田（以下简称柿竹园矿田）为研究对象，运用流体包裹体、稳定同位素和稀有气体同位素地球化学等方法，对其成矿流体的物理化学特征、来源及演化进行了研究，并在此基础上探讨了千里山花岗岩体与柿竹园矿田间的成因联系和矿田的成矿作用机制，获得以下主要研究成果： 1. 利用流体包裹体岩相学、显微测温学以及包裹体成分的激光拉曼分析技术，揭示了矿田中柿竹园钨锡钼铋矿床成矿流体的性质和演化特征。研究表明柿竹园钨锡钼铋矿床成矿流体为中高温、中高盐度H2O-NaCl-CaCl2-CO2-CH4-H2S-F体系。成矿流体的均一温度、盐度、密度和压力变化范围均较大，成矿早期夕卡岩阶段和云英岩阶段的流体具有较高的均一温度（239～477℃）和盐度（0～39.08 wt% NaCl eq.），云英岩网脉夕卡岩阶段和后期石英萤石脉阶段均一温度和盐度逐渐降低（分别为160～450℃，1.23～16.53 wt% NaCl eq.和156～340℃，1.23～4.49 wt% NaCl eq.）。夕卡岩阶段发生了流体沸腾作用。流体密度为0.37～1.12 g/cm3，主要集中在0.7～0.9 g/cm3；压力为10～820 bar，一般小于800 bar。野鸡尾锡铜矿床的成矿流体属于中高温度、中等盐度的H2O-NaCl-CaCl2-CO2-CH4-H2S-F型体系，柴山铅锌矿床属中温中等盐度H2O-NaCl-CaCl2-CO2-F体系，其均一温度和压力变化范围也较大。 2. 通过分析主要矿化类型矿石矿物及脉石矿物的C、H、O、S等稳定同位素特征，揭示了柿竹园矿田成矿流体的来源，并对C、O同位素的组成进行了CO2去气、流体混合和水―岩反应的理论模拟。研究表明矿田成矿流体主要来自千里山花岗岩浆，并有大气降水加入。水―岩反应在成矿过程中起着重要作用。 3. 对矿田不同矿化类型矿石矿物黄铁矿、黄铜矿、毒砂、方铅矿等进行了He、Ar同位素研究，其中3He/4He值为0.059～1.662 Ra（Ra为空气的3He/4He值，1 Ra＝1.39×10-6），40Ar/36Ar值为289.8～1071.8，表明矿田成矿流体具有壳-幔两端员混合的特征。壳源组分为获得了大量地壳放射成因4He，但获得放射成因40Ar*较少的经过地下循环的低温饱和大气水。而幔源组分来自千里山花岗岩浆流体，表明千里山花岗岩并非传统的S型花岗岩。 4. 在总结前人研究成果的基础上，结合本次研究，建立了柿竹园矿田成矿作用模式：中生代华南岩石圈发生拉张、伸展作用，地幔物质上涌，发生壳幔相互作用，形成千里山花岗岩浆。花岗岩浆充分分异演化形成富含挥发分和成矿元素的成矿流体，与泥盆系碳酸盐岩发生反应而沉淀成矿。成矿过程有大气降水的加入，并发生了流体沸腾作用。
其他摘要	The Nanling region is the most important rare metal and nonferrous metal ore source producing area, especially famous for large-scale metallogeny of W and Sn, and lots of large and superlarge deposits have been discovered in this region. Recent studies indicated that the formation of these deposits is probably related with large-scale crustal extension, lithosphere thinning and crust-mantle interaction in South China during Mesozoic. This study is focused on the fluid inclusion, stable isotope geochemistry and noble gas isotope geochemistry of the Shizhuyuan W, Sn, Mo, Bi, Pb, Zn polymetallic orefield. The geochemical characteristics and evolution mechanism of the ore-forming fluid are further discussed. In addition, the relationship between Qianlishan granites and Shizhuyuan polymetallic orefield, and the mineralization mechanism of the orefield are discussed as well. The main conclusions are listed as follows: 1. The results of the petrography, microthermometry and Laser Raman technique account for the nature and evolution characteristics of the ore-forming fluid of the Shizhuyuan polymetallic orefield. The ore-forming fluids are H2O-NaCl-CaCl2-CO2-CH4-H2S-F system in Shizhuyuan W-Sn-Mo-Bi deposit, with large range of homogenization temperature, salinity, density and pressure. Homogenization temperature and salinity were high in early skarn-stage and greisen-stage (homogenization temperature ranged from 239 to 477℃, and salinity ranged from 0 to 39.08 wt% NaCl eq.), and gradually decreased in stockwork stage (homogenization temperature ranged from 160 to 450℃, and salinity ranged from 1.23 to 16.53 wt% NaCl eq.) and quartz-fluorite vein stage (homogenization temperature ranged from 156 to 340℃, and salinity ranged from 1.23to 4.49 wt% NaCl eq.). The density ranged from 0.37 to 1.12 g/cm3, generally between 0.70 and 0.90 g/cm3, and the homogeneous instantaneous pressure of inclusions varied from 10 to 820 bar, generally less than 800 bar. The ore-forming fluids are H2O-NaCl-CaCl2-CO2-F system in Yejiwei Sn-Cu deposit and H2O-NaCl-CaCl2-CO2-F system in Chaishan deposit, with large range of homogenization temperature, salinity, density and pressure too. 2. The origin of ore-forming fluid was revealed by analyzing of C, H, O, S isotopes. Moreover, C and O isotopic compositions of degassing, mixing of two fluids and fluid-rock interaction processes were theoretically simulated. It indicated that the ore-forming fluid originated from the Qianlishan granitic magma with involvement of crustal circulated meteoric water. Meanwhile, fluid-rock interaction played an important role during mineralization process. 3. He and Ar isotope compositions of fluid inclusions in sulfides from the orefield are first determined by our study. 3He/4He ratios range from 0.059 to 1.662 Ra (Ra represents the 3He/4He ratio of air, 1.39×10-6), 40Ar/36Ar ratios range from 289.8 to 1071.8, which indicate that the ore-forming fluid was a mixture of two end-member components―mantle-source and crust-source. The crustal-source fluid was mainly consisted of the low temperature air saturated water, which subjected to crustal circulation and extracts a great deal of radiogenic 4He, but less radiogenic 40Ar from crustal rocks. The mantle-source fluid was derived from the Qianlishan granitic magma, which suggested that the Qianlishan granite was not typical S type granite. 4. Our study proposed an ore-forming mechanism of Shizhuyuan ore-field combined with considerations of literatures. In Mesozoic, lithosphere in south China suffered crustal extension and lithosphere thinning. Afterwards, crust-mantle interaction occurred and generated the granitic magma in Qianlishan. Subsequently, the granitic magma experienced a high differentiation and formed an ore-forming fluid which enriched in volatile and mineralized elements. Then the ore-forming fluid ascended and was metasomatic with carbonate of Devonian and therefore led to precipitation of ore-forming elements. The meteoric water was involved during the ore-forming process and fluid boiling occurred.
页数	118
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/3460
专题	研究生_研究生_学位论文矿床地球化学国家重点实验室
推荐引用方式 GB/T 7714	武丽艳. 柿竹园钨、锡多金属矿田成矿流体地球化学研究[D]. 地球化学研究所. 中国科学院地球化学研究所,2009.

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