西藏浪卡子县也金嘎波金矿岩石地球化学特征

也金嘎波金矿位于冈底斯成矿带上,是对区域化探发现的Au、As多元素组合异常进行追踪发现的,属于热液型金矿床。矿区各类岩石Au、As、Sb、W、Hg、Ag、Bi、Pb元素平均值高于中国丰度值数倍以上,表明矿区具有丰富的物质来源基础。岩石地球化学研究证明,矿床地表发育Au、As、Sb等10多个元素组合异常。其中Au是成矿指示元素,As、Sb、W是密切伴生元素,Bi、Ag、Pb、Hg是一般的伴生元素。多元素组合异常浓度带发育,浓集中心互相套合叠置部位指示金矿(化)体位置。矿体指示元素(Au、As、Sb、W、Hg、Bi、Ag、Pb)异常分布在岩体、地层接触带和构造交汇处,显示金矿与岩浆活动、热液作用和断裂构造相关,属多次构造作用、岩浆热液叠加富集而成。该金矿床处在冈底斯成矿带内,此研究对该成矿带金异常的识别和查证,寻找新的金矿具有借鉴意义。

GeoChemiCAl feAtureS of the yeJinGAbo Gold dePoSit in lAnKAzi County,tibet

Located in the Gangdese metallogenic belt, the Yejingabo gold deposit was found out by tracing Au, As multielement assemblage anomalies discovered by regional geochemical survey, and belonged to hydrothermal gold deposit. The abundances of Au, As, Sb, W, Hg, Ag, Bi and Pb in various rocks in the area are times higher than those in China in average, indicating that the area has abundant material sources. Petrogeochemical study showed that there are assemblage anomalies of more than 10 elements such as Au, As and Sb identified around the surface of the deposit. Of the elements, Au is ore-forming indicator, As, Sb and W are closely associated elements, and Bi, Ag, Pb and Hg are commonly associated elements. The multielement assemblage anomaly concentration zones are developed, with the overlaps of concentration centers indicating the place of gold ore (mineralization) body. Ore body element indicators (Au, As, Sb, W, Hg, Bi, Ag, Pb) anomalies occur at the contact of rock mass and stratum, and the meeting place of structures, implying that gold ore is associated with magmatism, hydrothermalism and faulted structure, and is a product of multiple stages of superimposition of tectonism, magmatism and hydrothermalism, and of enrichment. This deposit lies in the Gangdese metallogenic belt and this study is helpful to identification and test of gold anomalies, and prospecting of new gold deposits along the belt.