甘肃鹿儿坝金矿床地质特征及找矿标志

Geological Characteristic and Prospecting Indicator of Luerba Gold Mine in Gansu Province

鹿儿坝金矿是产于西秦岭中三叠统浅变质沉积岩建造中的大型金矿床。通过研究矿床地质特征、热液活动及围岩蚀变等特征,分析控矿条件,认为中三叠统碎屑岩夹碳酸盐岩建造是本区金成矿的母岩和围岩;近EW向构造控矿作用明显,近EW和NW向构造交会处是富矿体的赋存部位;矿体与闪长玢岩脉关系密切,在矿区深部为热液活动提供了热动力。矿区矿体赋存状态、矿石矿物组成和结构构造等特征表明,鹿儿坝金矿是浅成中—低温热液作用下形成的微细粒浸染型金矿床。同时,指出中三叠统碎屑岩夹碳酸盐岩建造、近EW与NW向断裂交会处以及闪长玢岩脉发育地段是该区有利的找矿标志,矿区各矿带在平面上具有等间距分布的特征,应作为下一步找矿的重点。

Luerba gold deposit is a large carlin type deposit occurred in the epimetamorphic sedimentary rocks of the Middle Triassic in western Qinling mountain.Through studing geological characteristics,hydrothermal activity and wall-rock alteration,analyzing ore-controlling condition,we consider that clasolite-carbonatite constnJetion of Middle Triassic are parent rocks of gold mineralization.The ore-controlling structure role of EW-trending is obvi- ous, and rich orebody always occurs in the zones where NW and EW-trending fractures intersect.The quartz diorit- ic porphyrite,which likely provides energy to the gold bearing solution transportation,plays a significant role in gold ore-forming process.Further analyzation shows that Luerba gold deposit is a large carlin type deposit,which formed under epithermal to mesothermal environment.Besides,the carbonates bearing clastic rock formation, the in- tersect zone of NW and EW trending fractures, and the quartz diorite porphyrite are beneficial prospecting indica- tors, the ore belt has the characteristics of equidistant parallel distribution, so we regard these factors can be as the focus of next prospecting.