新疆东天山香山岩体橄榄石特征及其成因意义

摘要

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 oli-vine 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-equilibra-tion of olivine from silicate liquid or sulfide liquid should be taken as an important factor for olivine composition.%新疆东天山香山镁铁-超镁铁杂岩体位于东天山镜儿泉-黄山镁铁-超镁铁质岩带的西段，由香山东、香山中、香山西3个岩体组成。其中香山中产出中型铜镍矿，香山西为小型铜镍-钒钛铁复合型矿床。香山岩体橄榄石为贵橄榄石，Fo值多为81.90～85.66，Ni 含量为638×10-6～2283×10-6。模拟计算得出香山岩体母岩浆 w （MgO）＝10.70％，w（FeO）＝10.66％，属于高镁玄武质岩浆。香山岩体橄榄石中Ni含量的最大值为2283×10-6，母岩浆中Ni含量为326×10-6，是由原始地幔发生14％的部分熔融而成。香山岩体在橄榄石结晶过程中伴随硫化物熔离，隙间硅酸盐和硫化物对橄榄石作用明显，造成早期结晶橄榄石成分改变。