造山型金矿成矿浅析——以青海省都兰县诺木洪郭勒地区为例

基于野外详细的地质调查及室内数据分析,研究认为哈拉郭勒与杏树沟金矿床均受东西、北西向压扭性断裂构造控制。成矿作用主要与印支晚期岩体有关。硅化、褐铁矿化、绢云母化、碳酸盐化、绿泥石化、高岭土化蚀变与金矿化密切相关。锆石U-Pb ICP-MS测年显示哈拉郭勒与杏树沟矿床成矿时间基本一致,为同源岩浆演化的结果;成矿期可分为:热液成矿作用和表生风化淋滤富集作用两个成矿期,其中热液期中石英-多金属硫化物阶段为最重要的成矿阶段。流体包裹体显示均一温度集中在160~240℃区间内,盐度集中在3.5%~7%NaCleq区间内,密度较低,成矿流体压力为128~240 MPa,成矿深度范围2.4~5.2 km之间;H、O同位素结果显示金矿床的成矿流体为岩浆热液和大气降水,属于浅成低温低盐低密度流体,认为该两矿床属造山型金矿床。

Metallogenesis of Orogenic Gold Deposit——Case Study of Nuomuhongguole Area of Dulan County in Qinghai Province

Based on a detailed analysis of field geological survey and interior data,the research suggests that both Halaguole and Xingshugou gold deposits are controlled by the east-west and north-west compression and torsion fault structures.The mineralization is mainly related to the late Indosinian rock mass.Silicification,limonite mineralization,sericitization,carbonation,chloriteization,kaolinization and alteration are closely related to gold mineralization.Zircon U-Pb ICP-MS dating shows that the mineralization time of Halaguole and Xingshugou deposits is basically the same which is the result of the cognate magma evolution.The mineralization period can be divided into two metallogenic periods:hydrothermal mineralization and superficial weathering and leaching enrichment in which the hydrothermal quartz-polymetallic sulfide stage is the most important mineralization stage.The uniform temperature of fluid inclusions is concentrated in the range of 160~240℃,the salinity is concentrated in 3.5%-7%NaCleq interval,and the density is low,the pressure of ore-forming fluid is 128~240 MPa,the mineralization depth range is 2.4~5.2 km.H and O isotopic results show that the ore-forming fluids of the gold deposit are magmatic hydrothermal fluid and atmospheric precipitation,which belong to shallow,low temperature,low salt and low density fluid.The two deposits are considered to be orogenic gold deposits.