| 湘南瑶岗仙钨矿床成矿流体地球化学 | |
| Alternative Title | Geochemistry of the ore-forming fluids of the Yaogangxian tungsten deposit in southern Hunan, China |
| 王巧云 | |
| 2007-03-20 | |
| Degree Grantor | 中国科学院地球化学研究所 |
| Place of Conferral | 地球化学研究所 |
| Degree Name | 博士 |
| Keyword | 瑶岗仙 石英脉型黑钨矿矿床 流体包裹体 激光拉曼测试 成矿物质来源 |
| Abstract | 瑶岗仙钨矿区地处南岭中段，位于加里东隆起带与印支-燕山凹陷带的交汇地带。为了更深入地研究瑶岗仙钨矿成矿流体的性质和演化，在前人工作的基础上，本文结合流体包裹体的岩相学特征及其产出的构造特征，对瑶岗仙钨矿流体包裹体进行了显微测温和激光拉曼探针分析，从而确定了瑶岗仙钨矿成矿流体的性质，并进一步探讨了其成矿物质来源及成矿机制。 对瑶岗仙石英脉型钨矿床的石英、萤石和矽卡岩型钨矿床中石榴子石流体包裹体的岩相学特征研究表明，与成矿有关的包裹体主要有三类：富液相、富气相和含子晶多相包裹体。脉型钨矿床中石英的包裹体均一温度范围 180℃～300℃，盐度为 0.88～6.45 wt% NaCl；矽卡岩钨矿床中石榴子石包裹体均一温度范围为 190～300 ℃，盐度为 0.1～8.95 wt% NaCl，成矿溶液的密度为 0.70～1.05 g/cm3，说明形成两种类型矿床的流体均属中温、低密度、低盐度流体；两类矿床形成的压力为 32～38 MPa，成矿深度为 1～2 km，因此该矿床是在浅成、低压条件下形成的。激光拉曼探针测试表明，石榴石包裹体的气相成分以 H2O 为主，石英中包裹体的气相成分及其相对含量为 H2O＞CO2＞CH4＞N2＞H2S。由此说明，从矽卡岩型白钨矿阶段到石英脉型黑钨矿阶段，成矿流体中不断有 CH4、CO2和H2O 等挥发份的加入，此时的流体是一种介于岩浆与热液之间的过渡性流体，具有上部偏液、下部偏浆的特点。 根据前人的研究结果以及矿脉中花岗岩角砾的发现，泥盆系、寒武系岩层在花岗岩浆侵入过程中发生了混合岩化，成为成矿物质来源的基础，而真正的成矿母岩应该是深部的花岗岩体，由此推测“赋矿花岗岩并非成矿源岩”，很可能来自深部母岩浆中熔离出的流体。而 CH4 等还原组分的含量增多，推测也有可能来自相对是还原环境的地幔过渡带或软流圈中。 |
| Other Abstract | The Yaogangxian tungsten deposit is located in the central part of the Nanling fold belt of South China, at the boundary between the Caledonian uplift and the Yinzhi-Yanshan depression belt. On the basis of prior researches of other people, nature and evolution of the fluid in the Yaogangxian tungsten deposit were defined by means of the lithology and texture feature, homogenized temperature, and composition of the fluid inclusions. The formation process of the Yaogangxian tungsten deposit and the source of the fluids have been discussed as well. There are three types of dominant metallogensis related fluid inclusion in Yaogangxian quartz-vein wolframite deposit and skarn scheelite deposit. They are liquid-rich inclusion, gas-rich two-phase inclusion and daughter-minerals bearing polyphase inclusion. The homogenized temperatures and salinity of fluid inclusions in quartz range from 180℃ to 300℃ and from 0.88 to 6.45 wt% NaCl, of the inclusions in garnet vary from 190℃ to 300℃ and from 0.1 to 8.95 wt% NaCl respectively. Density of the fluids are 0.70～1.05 g/cm3. These features represented that the fluids are medium temperature, low density and low salinity in these two types of fluids in this tungsten deposits. Pressure of the fluid was 32～38×106 Pa, indicating that the two types of tungsten deposits were formed at depth of 1～2 km. The compositions of the fluids analyzed by Laser Spectroscopy indicate that the fluid conclusions in garnet mainly consist of H2O, whereas, other volatile components, such as CH4 and CO2, also exist in the fluid conclusions of quartz. The sequence of the contents is H2O＞CO2＞CH4＞N2＞H2S. Therefore, from the formation of the skarn scheelite to the quartz-vein, the contents of these volatile components in the fluid were increased, and the fluid is the transitional fluid between the magma and hot liquid. The previous studies on gravels of granite in the deposit discovered that mixed-magma lithification occurred in the Devonian and Cambrian strata when granitic magma intruded these strata and made them the sources for the mineralization. However the real source was the granite in the deeper location. Therefore, the origin of the minerals substance was not the granite which endued with minerals, but most likely the melt fluid which came from the magma in the deep chamber. The increase of the deoxidize component, CH4, indicated that the origin was probably the mantle transition zone or asthenosphere which was deoxidized. |
| Pages | 61 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.gyig.ac.cn/handle/352002/3330 |
| Collection | 研究生_研究生_学位论文 |
| Recommended Citation GB/T 7714 | 王巧云. 湘南瑶岗仙钨矿床成矿流体地球化学[D]. 地球化学研究所. 中国科学院地球化学研究所,2007. |
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