REE and Trace Elements of Auriferous Pyrite from the Taishang Gold Deposit, Jiaodong, China: Implication for ore Fluid Evolution

The Jiaodong peninsula is the largest gold province in China, its proven gold reserve occupies 25% of the country's (Deng et al., 2006), the proven gold reserve in north-western Jiaodong peninsula occupies 90% of that of Jiaodong peninsula (Yang et al., 2014a). Zhaoping fault belt is the largest fault belt in north-western Jiaodong peninsula, within which the proven gold reserve is more than 1500t (Yang et al., 2014b). Taishang gold deposit is an important Jiaojia-type gold deposit in the northern part of Zhaoping fault belt, whose proven gold reserve is more than 100t. The Potouqing fault is the main ore-controlling fault, the hanging wall mainly consists of Linglong monzogranite and the footwall mainly consists of Luanjiahe monzogranite. The orebodies are controlled by Potouqing fault and its secondary faults. There are 9 main orebodies abut upon the fracture surface and the secondary orebodies are away from the fracture surface. Alteration type includes potash-feldspathization, sericitization, silication and carbonatation. Mineralization type includes fractured belt-alteration rock type and vein type. Pyrite, chalcopyrite, galena and sphalerite are the most common metallic minerals. The pyrites are euhedralsubhedral granular, mainly occur as mineral aggregation and veinlet type. The chalcopyrites are allotype granular, often coexist with pyrites. Pyrites and chalcopyrites mainly occur in the phyllic alteration rocks, silicified rocks, potash-feldspathization granites, quartz veins and the interface of quartz veins and wallrocks. Galenas coexist with other metallic minerals and occur as granule mineral aggregation. Sphalerites are mostly observed microscopically. According to the characteristics of alteration and mineralization in the field, hand specimen, petrography and ore microscopy observation, the mineralization stages are divided into the pyrite-quartz-sericite stage (I), the quartz-pyrite stage (II), the quartz-polysulfide stage (III) and the quartz-carbonate stage (IV). Stage I is the early mineralization stage. Quartz, sericite and pyrite are the common minerals. In this stage, pyrites are small in quantity, often shattered into pieces and disseminated in the milky white quartz and scaly sericites. Stage II is the main mineralization stage. Pyrites are subhedral cubic and become larger in quantity, often occur as vein-type aggregation. Stage III is the main mineralization stage. Pyrites, chalcopyrites, galenas and sphalerites coexist with each other and occur as the quartz sulphide vein. Stage IV is the late mineralization stage. The quartz is ash grey and irregular shape. Calcite is the main carbonate mineral and cuts through the earlier stage quartz. Pyrites are small in quantity and often occur in the calcite vein.