青海省纳赤台金矿床成矿流体特征及成因探讨

Ore-forming fluid and metallogenic genesis of Nachitai gold deposit,Qinghai province

纳赤台金矿床位于东昆仑造山带东段中部。矿体受地层和构造共同控制,一般产在断裂破碎带、构造裂隙及节理中。矿床成矿流体盐度为0.82%-13.29%,密度为0.61-0.97 g/cm^3;流体包裹体均一温度为195.9-443.1℃;成矿压力80.01 MPa,成矿深度为8.03 km。研究表明,该区中—晚元古代万保沟群碳酸盐地层提供了主要的成矿物质,晚华力西—印支期受构造造山作用影响,岩浆携带成矿流体、成矿物质沿断裂上升侵位,萃取围岩中大量的成矿物质,迁移至断裂破碎带或节理等部位沉淀成矿。总体上,该矿床为受地层和构造共同控制的中低温热液脉型矿床,相当于造山型金矿床系列的中成矿床。

Nachitai gold deposit locates in the middle of east section of Eastern Kunlun orogenic belt.Controlled by both strata and structures,the orebodies generally occurred in fractured belts,structure fractures and joints.The salinity of ore-froming fluid ranges from 0.82 % to 13.29 % and the density is in range of 0.61-0.97 g/cm3.The homogenization temperature ranges from 195.9 ℃ to 443.1 ℃.And the metallogenic pressure is about 80.01 MPa,correspondent to a depth of 8.03 km.Research shows that,the middle-late Proterozoic Wanbaogou group carbonate strata provided the main ore-forming materials,influenced by the late Variscan-Indosinian period structural orogenic effect;and the magma carried ore-forming fluids and materials to rise along the faults,extracting a lot of ore-forming materials from surrounding rock,and moved to the fractured zones or joints to sediment and form orebodies.Overall,Nachitai gold deposit is a middle-low temperature Hydrothermal type pulse deposit controlled by both strata and structure,correspond to middle forming type of orogenic gold deposits series.