Ore mineral characteristics of the Xiangshan copper-nickel sulfide deposits in East Tianshan Mountains and their metallogenic significance

Abstract： The well-known Huangshan-Jing'erquan Cu-Ni metallogenic belt in East Tianshan Mountains has lots of genetically similar copper-nickel deposits. Based on field investigation, the authors made electron microprobe analysis of the components and carried out a detailed study of the mineral composition of the copper-nickel ore deposits. The ore minerals can be classified into Fe-S series, Fe-Cu-S series, Fe-Co-Ni-S series, Fe-Co-Ni-As series, Fe-Co-Ni-As-S series and telluride. According to characteristics of mineral associations, the ore-forming process is divided into the magmatic liquation ore-forming period, the magmatic hydrothermal ore-forming period and the epigenetic weathering period. Based on calculating the crystal-chemical formula of these mineral compositions, this paper describes the modes of occurrence and geneses of these minerals. Zircon U-Pb age of (285 ± 1.2) Ma for Xiangshan rocks and and Re-Os isochron age of (298 ± 7.1)Ma for pentlandite suggest the consistency between the rock-forming and the ore-forming ages.