广东河台右旋韧性剪切带及其对金矿的控制  

Hetai Dextral Ductile Shear Zone,Western Guangdong, and Its Controlling on Formation of Gold Deposit

作　　者：蔡建新[1] 

机构地区：[1]中国科学院南海海洋研究所,边缘海地质重点实验室,广州510301

出　　处：《地质论评》2012年第6期1069-1080,共12页Geological Review

基　　金：中国科学院边缘海地质重点实验室开放基金(编号MSGL12-06)项目的成果

摘　　要：广东河台金矿位于广东西部的广宁杂岩体之中,为典型的韧性剪切类型矿床。几何学、运动学分析表明,河台韧性剪切带具有右旋性质,陡倾(>60°),走向N60°～80°E,与含金矿脉产状近于一致,与区域性N45°E走向韧性剪切带明显不同,为两个N45°E走向的右旋走滑断裂带间派生的右旋伸展走滑构造带。糜棱岩中石英包裹体和多硅白云母温度压力分析表明,韧性变形发生于中等温度压力(300～500℃、0.3～0.6GPa)的绿片岩相条件下,适宜金矿成矿。糜棱岩中提取的多硅白云母获得了187～192Ma的40Ar/39Ar坪年龄,表明韧性剪切导致的糜棱岩化及金矿化可能发生于早侏罗世。区域构造对比分析显示,河台金矿右旋韧性剪切带可能是太平洋构造域早侏罗世开始阶段诱导的远程斜向应力场的产物。The Hetai gold deposit is located in western Guangdong,China,belonging to a ductile shear type of gold deposit formed in an orogenic setting.Field investigation shows that the Hetai ductile shear zone has a similar attitude with the Au-bearing ore veins,both steeply dipping and striking N60°~80°E,which is distinctly different from the generally N45°E striking regional shear zones.Kinematic analysis indicates that dextral shear has prevailed in both trends of shear zones. Accordingly, the Hetai shear zone is better interpreted as an extensional relay structure between two regional dextral shear zones.The inclusion temperature and phengite molecular composition from mylonites reveal shear deformation under conditions of intermediate temperature—pressure（300~500 ℃,0.4~0.6 GPa）and greenschist facies,typically suitable for Au deposition.40Ar/39Ar dating on phengite from the mylonites obtained 187~192 Ma ages,thus confining the timing of the Au deposition to the Early Jurassic,a transition period from the Indosinian to Yanshanian orogenies at the initial stages of the Pacific tectonic realm.

关 键 词：广东河台金矿 韧性剪切带 早侏罗世 糜棱岩化 右旋走滑 

分 类 号：P618.51[天文地球—矿床学]