金坝金矿床成矿作用探讨及找矿条件、标志分析

MINERALIZING PROCESS AND PROSPECTING GUIDE OF JINBA GOLD DEPOSIT, SOUTHEAST YUNNAN

滇东南上二叠统、下三叠统及其基性岩浆活动为金坝金矿提供成矿物质 ,成矿流体主要来自印支期基性岩浆期后热液及部分大气降水 .桂西拗陷内隆起边缘基底断裂构造的多期次继承性活动是成矿热液循环迁移的动力 .地壳深部成矿热液 ,沿基底断裂及与其具成生联系的断裂构造系统上涌、运移 ,在高渗透性、易溶性岩石及富含有机质等还原介质环境中 ,通过渗透、扩散交代作用使金在褶皱断裂构造的合适部位沉淀 ,形成原生金矿床 .原生金矿抬升暴露地表 ,遭受风化淋失 ,而形成氧化矿 .

The Upper Permian and Lower Triassic strata and basic magmatism have provided ore-forming material for Jinba gold deposit in southeast Yunnan Province. The metallogenic fluids are derived mainly from Indosinian postmagmatic basic hydrothermal solution and partly meteoric water. The multistage inherited movement of the basement faults on the upwelling margin in Guixi depression supplied dynamics for the circulation and migration of ore-forming solution.The ore-forming solution from the deep crust upwelled and transported along the basement faults and associated fractures. The permeation and diffusion metasomatism resulted in the precipitation of gold in favorable positions of fold and fault structures in an enironment of high-permeable and readily soluble rocks and organic material riched reduced media.The primary gold deposit was then uplifted to the surface, and weathered to oxydized ore.