河南省桐柏县银洞坡金矿成矿作用

银洞坡大型金矿床赋存于上古生界的一套炭硅泥建造中,黄铁矿标型具有沉积成因与热液成因的过渡属性.矿石稀土元素配分曲线右缓倾,不具Eu异常,与中生代梁湾花岗岩有亲源性.硫同位素δ34S为3.1%,均一化程度高.矿石和围岩铅同位素的组成相近,来源于向北陆内俯冲而叠置于北秦岭地体之下的南秦岭陆壳的部分融熔.氢氧同位素组成指示成矿流体来自于大气降水和岩浆水、变质水共同演化而成.矿床成矿作用经历了原始沉积矿源层形成、低级变质-成矿物质初步富集和岩浆-天水混合热液驱动成矿物质定位3个阶段.

MINERALIZATION OF THE YINDONGPO GOLD DEPOSIT IN TONGBAI COUNTY,HENAN PROVINCE

The Yindongpo gold deposit is situated in an upper Palaeozoic carbon-silicon-mud formation. The pyrite typomorphic mineral shows a transitional attribute between the sedimentary origin and the hydrothermal origin. REE patterns assume gentle inclination towards the right without Eu anomalies. REE of ores and Liangwan granite have close relationship in sources. Sulphur isotope δ³⁴S is 3.1%, with high homogenization. Ores and wall rocks have similar lead isotope composition. They were derived from partial melting of South Qinling continent crust which subducted under North Qinling block. Compositions of radon and hydrogen isotopes indicate that ore-forming fluids came from joint evolution of meteoric, magmatic and metamorphic water. Mineralization has experienced three stages, namely, the formation of original sedimentary mineral source bed, the low-grade metamorphism and the preliminary enrichment of ore-forming elements, and the locating of ore-forming elements derived from mixed hydrothermal water.