鄂东丰山矿田卡林型金矿地质地球化学特征

鄂东丰山矿田主要由丰山 (封山洞 )铜矿床、鸡笼山金铜矿床和李家湾铜矿床组成。经野外调查和室内研究 ,确认矿田内存在卡林型金矿 ,金平均品位约 5× 1 0 -6,远景储量在大型以上。该卡林型金矿的主要特征是 :(1 )分布于丰山斑岩体周围的中酸性岩脉发育区 ;(2 )容矿岩石为下三叠统大冶组薄层状 -纹层状和角砾状碳酸盐岩 ;(3)矿体主要受高角度断层控制 ,通常产于岩脉的一侧或附近 ;(4 )矿石普遍具白色细网脉状方解石化和碳泥化 ,裂面上常见黑色碳质被膜 ;(5 )金主要为次显微金 ;(6 )成矿物质主要来自矿源层 ,部分来自岩浆 ,成矿热液水主要来自大气降水

GEOLOGIC AND GEOCHEMICAL FEATURES OF THE CARLIN-TYPE GOLD ORE IN FENGSHAN OREFIELD OF EASTERN HUBEI

The Fengshan orefield consists of the Fengshan Cu deposit, the Jilongshan Au-Cu deposit and the Lijiawan Cu deposit, which are skarn-porphyry-type deposits. Based on the field on-site survey and the laboratory study, it is confirmed that the Carlin-type gold deposit exists in the orefield, its Au average grade is about 5×10~(-6), and its prospective reserves are above the large-scale size. The deposit is of the following characteristics: (1) Gold mineralization is distributed within the developed area of the intermediate-acidic dike in the periphery of the Fengshan porphyry body; (2) Ore-host is weakly marbleized veneer and brecciated carbonate rocks of Daye Formation of Triassic system; (3) Orebody is mostly controlled by high-angled faults and is generally located within a side of the dike rock or near it; (4) Ore-host rock is generally white stockwork veinlet calcitization with pelletal, strawberry-like and disseminated veinlet pyrite and with black carbonaceous coating film on its cataclastic surface; (5) Gold occurs chiefly as the submicro gold grade. Most metallogenic materials were derived from source beds and some from magma; the metallogenic hydrothermal water was derived from meteoric water.