陕西太白南部西坝复式岩体的成因及其与双王金矿床的关系

THE GENESIS OF XIBA COMPLEX INTRUSION AND ITS RELATIONSHIP WITH SHUANGWANG GOLD DEPOSIT IN SOUTHERN TAIBAI, SHAANXI PROVINCE

本文认为西坝复式岩体由第一期的石英二长闪长岩(Rb-Sr同位素年龄213.5Ma)和第二期的二长花岗岩(K-Ar同位索年龄198.3～202Ma)组成。两期岩浆岩的岩石化学、稀土元素组成和同位素特征等表明,它们同属一个系列,由来源于上部地幔的岩浆经过演化而形成。从岩体的Au含量、岩体和矿床的Pb同位素组成推测,岩体和双王金矿床之间无物质成分方面的联系。借助于传热学方法分析岩体的热影响,亦未发现有控制金矿床形成的迹象。总之,岩体与双王金矿床无关。

This paper suggests that Xiba intrusion can be divided into two stages, the first is quartz monozonitic diorite and its Rb-Sr age is 213.5 Ma, the second is monozonitic granite and its K-Ar age is 198.3~202 Ma. The characters of petrochemical, REE and isotope of the intrusion show that two stages are a continuous series which were evolved from magma derived from the upper mantle. It is deduced from the Au content of the intrusion, characters of Pb isotope and REE between the intrusion and gold deposit that there does not exist any relationship in material and composition between the two bodies. It is also analysed by means of heat transfer method that the thermal effect of the intrusion could not control the formation of the gold deposit. In conclusion, there is no relationship between Xiba intrusion and Shuangwang gold deposit.