云南墨江含金脆—韧剪切构造带中显微构造的矿物地球化学研究

墨江－元江镍金矿床是哀牢山构造－成矿带上一个十分典型和重要的矿床，在野外实测构造岩石地层层序、矿物学详细填图的基础上，采用X射线粉晶衍射分析、扫描电镜、电子探针微区分析及矿物－构造－地球化学等方法，对墨江镍金矿床中含金脆－韧性剪切构造带的物质组成进行详细研究。显微构造的矿物地球化学研究是一种构造筛分新方法。脆性构造主要表现为含镍金石英脉－硅质岩－黄铁矿硅质岩中普遍发育碎裂岩化及裂隙，碎裂岩化－裂隙构造是深源热流体叠加成矿的储矿构造和运移上升通道，脆性剪切变形过程中伴有粘土化蚀变，粘土矿物主要有铬水云母、铬高岭石、多水铬高岭石、绿铬高岭石、铬蒙脱石、铬迪开石、铬埃洛石和绿鳞石等。在含金脆－韧剪切构造带中，铬绢云母－铬水云母－铬伊利石系列和铬绿泥石的矿物具（脆）韧剪切变形特征，在韧剪切变形过程中伴有强烈的热流体以及H2O为主要组分的矿化剂作用。

MINERAL GEOCHEMISTRY ON MCRIO STRUCTURES IN THE MOJIANG Au-BEARING BRITTLE-DUCTILE SHEAR ZONE IN YUNNAN

The Mojiang Yuanjian Ni Au deposit is one of the most important and the most typical mineral deposits along the Ailaoshan tectono metallogenic belt. Based on research and analysis of the tectono lithostratigaphic unit and mapping of mineral geochemistry, as well as X ray powder diffractogram, scanning electron microscopic spectrum detection, electron microprobe analysis and tectonics mineral geochemistry, the characteristics and mineral composition of the brittle ductile shear zone in the Mojiang Yuanjian Ni Au deposit have been discussed in detail. The brittle ductile shear zone, the mainly ore hosted structure, includes proximate horizontal tension cracks, sinistral shear fractures and close off brittle ductile shear zones. Firstly, in the thrust nappe type shear belt in the Indo Chinese orogen perhaps is formed the Au bearing brittle ductile shear zone. Secondly, the strike slip type shear zone with a high angle was probably formed in the Early Yanshanian orogen, and then changed into brittle deformations in the late Yanshanian orogen. Finally, the Au orebodies of high grades were superimposed by deep source hydrothermal fluids in the Himalayan orogen. The brittle tension cleavages are the best ore hosted structures for Au orebodies of high grades. Brittle deformation tectonics in the brittle ductile shear zones is accordant to alterations of Cr clay minerals, which include Cr hydrmiscovite, Cr kaolinite, Cr hydrokaolinite, blue Cr kaolinite, hydrokaolinite and Cr smectite. The typical brittle tension deformation includes cataclasitization of quartz vien chert pyritic chert and cleavages in the shear zone, where they are attached to the ore host tectonics and the passway of thermal fluids derived from deep source. In the Au bearing brittle ductile shear zone, research on microstructure and mineral geochemistry of the Cr sericite Cr hydromuscovite Cr illite series and chlorite series revealed that they would be formed in the (brittle) ductile shear deformational zone involving extensive fluids and H2O type mineralizers.