胶西北大尹格庄金矿区青磐岩化与金成矿关系

Relationship between propylitization and gold mineralization in the Dayingezhuang Gold District,northwest Jiaodong

大尹格庄金矿区位于招平断裂带中段,矿区围岩蚀变分带现象明显,其中青磐岩化蚀变带呈面状分布于胶东群变质岩中。岩矿鉴定、X射线微区衍射分析及电子探针分析显示,该矿区青磐岩化蚀变岩的典型蚀变矿物组合为钠长石-赤铁矿(磁铁矿)-绿泥石-斜黝帘石-金红石-方解石,显示矿区青磐岩化蚀变形成于高氧逸度、偏碱性物理化学条件。大尹格庄金矿区水岩反应与成矿作用可以表述为电解-电离机制,即金离子在阴极获得电子而聚集成矿。青磐岩化蚀变带则为阳极,也是金成矿的主要物源区和活化区之一。水的电离作用是水岩反应与成矿的关键制约因素之一。

The Dayingezhuang Gold District is located in the middle section of the Zhaoping fault zone.Alteration zonation of surrounding rocks in the district is distinct.The propylitization alteration is in planar distribution in the metamorphic rocks of Jiaodong Group. According to rock-mineral identification,micro-area X-ray diffraction analysis and electron probe analysis,the typical mineral assemblage of propylitization is albite-magnetite (hematite)-chlorite- clinozoisite -rutile-calcite,and the propylitization alteration is formed in high oxygen fugacity and alkaline physicochemical conditions.The water-rock interaction and mineralization in the Dayingezhuang Gold District could be expressed as an electrolysis-ionization mechanism,in which gold acquires electrons at the cathode and aggregates into ore,whereas propylitization alteration zone,as the anode,provides the main material of gold mineralization in activation zones.The ionization of water is a key constraint to hydrothermal reaction and mineralization.