新疆冰达坂含金剪切带内组分分异及对金矿化的影响

Compositional Variation of the Bingdaban Gold-bearing Shear Zone and Its Significance to the Gold Mineralization in Xinjiang

新疆冰达坂含金剪切带内高品位金矿体更倾向定位于低应变带。选取典型剖面,对比蚀变围岩、矿石、未蚀变花岗质初糜棱岩及花岗质原岩组分特征,结果表明花岗质岩石容矿的金矿床剪切变形过程中组分发生分异,动力分异与流体分异对金矿化所起作用及相对程度不同,研究区金成矿主要与流体分异作用有关。流体分异作用过程中,相对于高应变带,低应变带内强分异形成的高Fe环境及扩容空间为金矿化、沉淀提供更有利条件,且碱(Na)交代排出的Si为浅层次硅化蚀变糜棱岩型及石英脉型矿化提供物源基础,K、Ca、Mg形成绢云母化、碳酸盐化、绿泥石化等蚀变,从而为区内金矿化定位及共生蚀变提供了合理解释。结合已有研究成果,认为钠长石化带下部应发育钾长石化带,且作为矿根相存在,矿带东、西段深部均有较好金矿化前景。

Bingdaban gold orebodies with high grade in Xinjiang is mainly located in the lower strain zone. By choosing typical cross section to compare the alteration countryrock, ore and granitoid protomylonite with their original rock Neoproterozoic granitoids, mineralization features and commensal alteration can be rationaly explained. Compositional variation plays an important part in gold mineralization. Findings show that composition differentiates with different effect from original rock to tectonite in the process of shearing, including dynamic variation and hydrothermal variation, the interaction between dynamic variation and hydrothermal variation resuits in gold mineralization. Dynamic variation mainly generates power and passage to hydrothermal fluxion and deposition space to gold mineralization, which to some degree also provides chemiphysical conditons to the decoupling of Aucomplex compound such as Fe enrichment and alkali metasomatism, however, dynamic variation could not singly result in gold mineralization with high grade. In the process of hydrothermal variation, comparing with the higher strain zone like alteration country rock, the lower strain zone like ore offers better chemiphysical conditons to gold mineralization, such as higher Fe enrichment and expanding space like D, Ptype shearing fractures, where gold ore can locate. Meanwhile, due to the effect between alkali （especially Na） metasomatism and Si,K,Ca, compositions differentiate from the deeper layer to the lighter layer, which supplies stuff base for silication and quartzvein gold mineralization in the lighter layer with country rock alteration such as sericitization, carbonation, chloritization and so on. According to these findings, potash （especially Kf） alteration which may show as ore foot facies can be inferred under albitization alteration, which means there are some blind gold orebodies under both the deeper layer like Saridala tion belt. and the lighter layer like Wangfeng along the gold mineraliza