Abstract:

The Xiangshan mafic-ultramafic complex was located in western part of Jing’erquan-Huangshan ma-fic-ultramafic rock belt, composed of the eastern part (Xiangshandong), the central part (Xiangshanzhong), and the western part (Xiangshanxi). Midium sized Cu-Ni sulfide deposits occur in the central part, and small sized Cu-Ni sulfide deposits and Fe-Ti-V oxide deposit occur in the western part. Electron microprobe analyses of olivine show that almost all the olivine crystals are chrysolite with the forsterite content (Fo) ranging from 81.90 to 85.66 and the Ni content ranging from 638×10^-6 to 2,283×10^-6. The content of MgO is about 10.70%, and the content of FeO is about 10.66% in the parent magma, which suggests that it belongs to high MgO basaltic magma.The Ni content with a maximum of 2,283×10^-6 in olivine indicates that the Ni content of the primitive magma is 326×10^-6; therefore, we can speculated that the primitive magma occured when 14% of the primitive mantle was melted. Sulfide separation and fractional crystallization happened simultaneously. The re-equilibration of olivine from silicate liquid or sulfide liquid should be taken as an important factor for olivine composition.

Key words: Xiangshan complex, olivine, component characteristics, Eastern Tianshan, Xinjiang