湖北大冶铜山口斑岩-矽卡岩型铜钼矿床包裹体特征及流体演化意义

Significance of inclusions and fluid evolution of the porphyry-skarn copper-molybdenum deposit in Tongshankou,Daye,Hubei

为了提供矽卡岩岩浆成因证据,丰富多成因矽卡岩理论,并研究湖北大冶铜山口铜钼矿床成矿流体性质,以包裹体的岩相学观察为基础,结合高温流体包裹体显微测温和激光拉曼光谱分析,对铜山口矿床矽卡岩矿化进行了研究。结果表明:在早期矽卡岩矿物石榴石中发现了丰富的晶质和非晶质熔融包裹体、熔体-流体包裹体,表明天然岩浆珠滴被矽卡岩矿物晶格缺陷捕获,其中含有石榴石、黄铜矿等子矿物,且早期流体包裹体均一温度超过500℃,为早期矽卡岩岩浆熔体成因提供了重要证据。矽卡岩成矿早期以岩浆作用为主,晚期以热液作用为主,且熔-流转换的过程主要发生在干矽卡岩阶段,早期岩浆熔体中富含成矿物质,为矿区深部成矿提供了物质基础。

Magma-skarn is an important genetic type among the multi-genesis of skarns.Based on petrographic observation and thermal microscopy temperature measurement of inclusions,combined with laser Raman spectroscopy,characteristics of ore-forming fluids at the Tongshankou porphyry-skarn copper-molybdenum deposit has been studied.This study aims to provide evidence for the formation of the magma-genetic skarn and further to unveil the melt-flow conversion processes and metal enrichment mechanism of ore-forming fluids.A vast amount of crystalline and amorphous melt inclusions and melt-fluid inclusions the melt inclusions have been found in the skarn minerals,e.g.garnet in the early stage,indicating that the magma droplets could have been trapped by the early skarn minerals.These inclusions could provide essential evidence for the magmatic genesis of the early skarns.With the comparison of different types of inclusions in the skarn minerals at each stage,it is believed that the skarn is dominated by magmatic genesis in the early stage,and the hydrothermal genesis in the late stage.Moreover,the processes of melt-flow conversion mainly occur in the prograde skarn stage.Ore minerals,e.g.chalcopyrite,found in the melt inclusions through the laser Raman analysis indicate that the skarn magma is rich in ore-forming materials at the Tongshankou deposit,which could aid in the deep prospecting and exploration in this area.