海南省东方市踏王山金矿床流体包裹体特征及矿床成因

Characteristics of fluid inclusions and genesis of Tawangshan gold deposit in Dongfang County,Hainan Province,China

踏王山金矿位于海南省戈枕金矿带东南部,矿体主要产于东西向构造蚀变带中,矿石类型为蚀变岩型和石英脉型。在详细的野外地质调查基础上,对踏王山金矿床流体包裹体特征进行研究,并结合矿体产出形态特征,对流体来源以及矿床成因进行探讨。结果表明:矿区流体包裹体主要为气液两相包裹体和纯CO_2包裹体,成矿流体具有中低温(均一温度为192~362℃)、中盐度(平均值为7.52%)及低密度(0.46~0.87g/cm^3)的特征,成矿深度为中深环境。从包裹体成分上看,流体包裹体既有岩浆水特征(高H_2O、H_2含量,w(F-)/w(Cl-)≥1),又具有地下热卤水的特征(w(Na^+)/w(K^+)>1),明显富集Ca^(2+)或者Ca^(2+)含量较高的成分,显示可能为混合流体。矿床成因为岩浆热液与地下热卤水叠加的复合型中低温热液矿床。

The Tawangshan gold deposit is located in the southeast of Gezhen gold ore belt in Hainan Province. The orebody is hosted by east-west tectonic alteration zone. The main mineralized types are altered rock type and quartz vein type. Based on the detailed field geological survey, the characteristics of fluid inclusions were studied, and the origin of ore-forming fluid and deposit genesis were discussed. The results indicate that, in Tawangshan mine area, the fluid inclusions are gas-liquid two-phase type and pure CO_2 type, and the characteristics of moderate or low temperature（in homogeneous temperature range of 192-362 ℃）, moderate salinities（average of 7.52%）, low density（0.46-0.87 g/cm^3） and moderate-deep metallogenic depth environment. The composition of fluid inclusions of Tawangshan gold deposit shows that the fluid inclusions have characteristics of both magmatic water（high H_2 O, H_2 content, w（F-）/w（Cl-）≥1） and geothermal brine water（w（Na＋）/w（K＋）1）, which represents mixing of magmatic water and geothermal brine water, obviously rich in Ca^2＋ or component with high Ca^（2＋） content. The genesis of Tawangshan gold deposit belongs to the moderate to low temperature hydrothermal deposit complexing with magmatic water and geothermal brine water.