青海省沱沱河地区楚多曲铅锌矿床流体包裹体特征及矿床成因探讨

青海省沱沱河地区楚多曲铅锌矿为近年来发现的一处大型铅锌矿床。铅锌矿体主要呈脉状产出,主要受控于切割碳酸盐岩地层的陡倾断裂。通过对系统流体包裹体研究,结果表明,石英中流体包裹体较为发育,主要为气液两相包裹体。成矿流体均一温度为160~220℃,盐度w(NaCl)为8%~10%,密度为0.90~0.95g/cm3,具有低温、低盐度、低密度的特征。估算成矿压力为11~13MPa,深度为1.1~1.3km,属浅成深度。成矿流体δD为-96.4‰~122.1‰,δ18 OH2O值为2.1‰~9.5‰。综合区域构造背景、铅锌矿体形成特点、流体包裹体特征及矿石组构等相关信息,认为楚多曲铅锌矿矿床成因类型为受断裂控制的中低温热液脉型铅锌矿床。该认识可极大拓展青海省沱沱河地区铅锌矿的找矿潜力,具有重要的研究意义和实用价值。

Characteristics of Fluid Inclusions and Ore Genesis of Chuduoqu Pb-Zn Ore Deposit in Tuotuohe Area,Qinghai Province

The Chuduoqu Pb-Zn deposit is a large newly found mineral deposit in Tuotuohe of Qinghai Province. Its ore-bodies occur as veins, controlled by the steep fracture that cut the car- bonatite strata. The research of fluid inclusion shows that fluid inclusions are well developed in quartz, mainly in gas-liquid phase. The ore-forming fluid is characterized by medium-low temper- ature （160-220℃）, low salinity （8%-10%NAC1） and low density （0.90-0.95 g/cm3）, with pres- sure of 11 to 13 MPa and depth of 1.1 to 1.3 km. The 3D value of the ore-forming fluid is - 122. 1%0 to -96.4%0 and the 318OH20 value is 2.1%0 to 9.5%0. Combined with the regional tecton- ic background, ore-forming characteristics of lead and zinc, fluid inclusions and ore fabrics, this paper summarized that Chuduoqu Pb-Zn deposit is a medium-low temperature hydrothermal vein Pb-Zn deposit controlled by fractures. This conclusion is of great academic and applied signifi- cance to improve lead-zinc ore potential in Tuotuohe area.