陕西八卦庙金矿床硅同位素组成及地质意义

八卦庙金矿床是秦岭泥盆系地层中发现的特大型金矿床。矿床分布于佛坪隆起西缘增生体向西侵入的前锋区。赋矿岩层为上泥盆统底部铁白云质粉砂千枚岩。矿床受区域ＮＷ向剪切断裂、ＮＥ向断裂与解理密集带交汇部控制。硅同位素组成有两组，分别与本地区泥盆系地层热水沉积物和印支—燕山期中酸性岩浆岩硅同位素相近，表明成矿流体早期以地层源为主，晚期以岩浆源为主。成矿作用与动力变质作用和岩浆活动的关系，显示了金矿与铅锌矿同属海西运动以来的一个大的岩浆－地下热水系统不同岩浆演化阶段的产物。

THE SILICON ISOTOPE GEOCHEMISTRY AND ITS GEOLOGICAL MEANING OF THE BAGUAMIAO GOLD DEPOSIT, SHAANXI

As one super large gold deposit hosted in the Devonian of Qinling, the Baguamiao gold deposit is located on the frontier of the west invasion of the Fuping rising accretion torrain. The ore-hosting rocks are iron-bearing dolomitic silt and phyllite of lower part of Upper Devonian. The deposit is controlled by the convergence of regional NW-trending shear fault and NE-trending fault and dense cleavage. The two clusters of silicon isotopes of ores are consistent with silicon isotopes of Devonian thermal sediments and Yanshannian magmatic rocks respectively, which indicates that the ore-forming fluid is derived mainly from strata early and from magmatism lately. The mineralization is related to dynamic metamorphism and magmatism. It is convinced that the gold deposit and Pb-Zn deposit represent products of the same large magma- underground water circulating system at different stages.