陕西周至马鞍桥金矿床地质特征及成因分析

THE GEOLOGICAL CHARACTERISTIC AND FORMATION IN MA AN QIAO GOLD DEPOSITE, ZHOU ZHI, SHAANXI

阐述了马鞍桥金矿区的地层、构造、岩浆岩特征，总结了金矿床矿体、矿石及化学成分的基本特点，分析了围岩、剪切构造带、中酸性岩体与金矿化的关系，认为马鞍桥金矿的成矿物质来源于围岩泥盆系罗汉寺岩群，成矿作用严格受脆性剪切变形变质带控制，剪切同期中酸性岩浆活动为含矿热液上升迁移和富集成主矿体提供了必要的热能。含矿热液与韧性剪切变质岩之间交代作用的强度是导致金的沉淀和富集形成金矿体的关键。矿床为韧性剪切带蚀变岩型金矿。

Ma An Qiao’s metallogenic materials might be from the wall rock of Luo Han Si group,Devonian system, which is due to not only studying the charactenistic of strata, structureand magma in this gold deposite area, but also summarizing ore bodies, ore and chemicalcompositions, the relationship between wall rocks, shear belts and intermediate-acid magmawith gold mineralization. The mineralizing process is controlled strictly by the metamorphism belt with ductile-brittle shear-deformation. The intermediate-acid magma activity during the shear movement may provide the necessary thermal energy for the upward migrationand accumulation of ore-bearing liquid. The metasomatism between ore-bearing liquids andthe metamorphic rocks undergone ductile-shearing deformation may play a key role in theprecipitation and accumulation of gold deposits. It is concluded that Ma An Qiao gold depositis altered one in ductile-shearing belt.