云南播卡金矿成因分析

Genesis of Boka gold deposit,Yunnan province

播卡金矿位于扬子地台西缘康滇地轴中南段的东北侧,容矿地层为中元古界昆阳群的因民组和平顶山组岩石和部分中-基性脉岩,矿床受小江脆-韧性剪切带的直接控制,矿床形态为透镜状、脉状、囊状等;矿体规模小,数量多,矿石以构造角砾岩型及石英脉型为主,矿物组合较为简单;围岩蚀变发育,且与矿化关系密切;流体包裹体测试结果显示,矿床成矿温度为114.5～236.7℃,属弱酸性环境下的中-低温成矿;矿石氧同位素、硫同位素测试结果表明,成矿流体以地下热卤水为主,混合了部分岩浆水和大气降水。矿床的成因类型应属与脆-韧性剪切带有关的含金剪切带型金矿。

Boka gold deposit is located in the middle-south Kangdian axis, west margin of Yangzi platform, hosted by rocks （carbonaceous slate, carbonaceous sandstone） of Yinmin Formation and Pingdingshan Formation of Mesoproterozoic Kunyang group and intermediate-basic dykes and controlled by Xiaoyajiao-Jiangjiawan brittle-ductile shear zone. There are numerous ore bodies in lens, vein and chamber but ore is dominated by breccia and quartz vein types with simple mineralogy. Wallrock alteration is developed and closely related to mineralization. The deposit is a medium-epithermal Au deposit formed at range of 114.5-236.7℃ under weak acidic condition according to fluid inclusion measurement and ore fluid dominated by hot underground brine incorporated with magmatic and meteroic water. Genetically, Boka gold deposit is a shear zone type gold deposit.