赣中地区大王山钨多金属矿床流体包裹体特征及其地质意义

发布时间：2018-03-26 10:29

  本文选题：大王山钨钼多金属矿床　切入点：山心岩体　出处：《东华理工大学》2017年硕士论文

【摘要】：大王山钼钨多金属矿床位于中国东南部江西省的中部,地处抚州市宜黄、乐安、崇仁三县交界处,位于大王山-于山多金属成矿带北端。矿石类型主要为脉状型黑钨矿,矿脉主要产于围岩花岗岩内的接触带中。本文在分析大王山矿区地质背景和成矿地质特征基础上,结合前人对研究区赋矿山心单元的细粒二云母二长花岗岩岩石地球化学特征、锆石U-Pb年代学特征的研究,系统开展了石英-辉钼矿脉中的石英矿物和硫化矿的流体包裹体、稳定同位素地球化学等方面的研究工作。通过系统总结赋矿岩体形成时代、成因类型及其形成构造环境,并结合大王山钨钼多金属矿床的成矿流体特征、成矿物质来源,初步建立了该矿床的成矿模型,进而对研究区成矿理论的确定及矿产勘探工作起到重要的指示作用。以下是本次研究获得的主要成果:(1)根据前人(项目组)对赋矿山心单元花岗岩体的研究资料,可以看出研究区花岗岩体具有高钾钙碱性、准铝质-过铝质、富硅碱,贫镁钙,高铁镁指数等化学成分特征,具有壳源花岗岩的特征,属于高热花岗岩。其源岩可能为变沉积岩,推断属于高分异S型花岗质岩石。(2)大王山矿区石英脉的石英流体包裹体均一温度为180~280℃(峰值为190~210°C),盐度为7.86%~20.22%NaCleqv(峰值11~17%NaCleqv)。利用硫同位素温度计计算成矿温度为315~339℃。由此看出,硫化矿要早于石英脉形成,其形成温度亦高于石英脉,结合前人对其它石英脉型黑钨矿床中的黑钨矿和石英脉的均一温度特征,可以判断该矿床应属于中高温、中高盐度的矿床。(3)研究区的氢氧同位素数据研究表明:石英包裹体中的δDV-SMOW值介于-72.5‰~-93.1‰,δ18OH_2O值介于-2‰~1.8‰,从石英包裹体的温度-盐度关系图中,推断矿区成矿流体在演化的过程中经历了流体的混合作用和自然冷却,进一步指示了黑钨矿要早于石英结晶,该时期成矿流体成分相对单一,以岩浆水为主,而石英结晶时成矿流体则体现了岩浆水和大气降水的混和作用。在岩浆液态不混溶作用过程中,W、Mo等多金属成矿元素以及挥发份不断富集,进而形成石英脉型钨多金属分异富集成矿。(4)硫化物硫同位素组成δ34S介于-1.3‰~+1.9‰之间,其中以-1‰~0.6‰之间者居多,平均值为-0.22‰,δ34S值主要集中在零值附近,说明硫源与深部岩浆有关。(5)通过对大王山钨多金属矿区的地质特征、成矿物质来源、成矿流体性质、大地构造背景、成矿机制等进行综合性研究,建立了该矿床的成矿模式。
[Abstract]:The Dawangshan molybdenum and tungsten polymetallic deposit is located in the middle of Jiangxi Province in southeastern China. It is located at the junction of the three counties of Yihuang, Le'an and Chongren in Fuzhou, and is located at the northern end of the Dawangshan-Yushan polymetallic metallogenic belt. The ore type is mainly vein type wolframite. The ore vein mainly occurs in the contact zone of surrounding rock granite. Based on the analysis of geological background and ore-forming geological characteristics of Dawangshan mine area, combined with the petrogeochemical characteristics of fine-grained dimica monzogranite bearing mine core units in the study area, The U-Pb chronological characteristics of zircon have been studied systematically in the aspects of fluid inclusions and stable isotope geochemistry of quartz minerals and sulphide ores in quartz-molybdenum veins. The metallogenic model of the deposit is preliminarily established by the genetic type and its forming tectonic environment, combined with the ore-forming fluid characteristics of the Dawangshan tungsten and molybdenum polymetallic deposit and the source of the ore-forming material. Thus, it plays an important role in the determination of metallogenic theory and mineral exploration work in the study area. The following is the main achievement of this study: 1) according to the research data of granitic bodies in mine core units by predecessors (project teams), It can be seen that the granite body in the study area has the characteristics of high potassium calc-alkalinity, quasi-aluminum-peraluminous, silicon-rich alkali, poor magnesia-calcium, ferric-magnesium index, etc., and has the characteristics of crust-derived granites. The source rocks may be metamorphic rocks. It is inferred that the homogeneous temperature of quartz fluid inclusions in quartz veins of Dawangshan mining area is 180 ~ 280 鈩，

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