Olivine Compositional Mapping of Mafic-Ultramafic Complexes in Eastern Xinjiang(NW China):Implications for Cu-Ni Mineralization and Tectonic Dynamics  

作　　者：Benxun Su Kezhang Qin He Sun Dongmei Tang Qinghua Xiao Pingping Liu Patrick Asamoah Sakyi 苏本勋;秦克章;孙赫;唐冬梅;肖庆华;刘平平;Patrick Asamoah Sakyi(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Department of Geology,University of Ghana,Legon-Accra,Ghana)

机构地区：[1]Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Department of Geology,University of Ghana,Legon-Accra,Ghana

出　　处：《Journal of Earth Science》2012年第1期41-53,共13页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos. 41030424,41173011);the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-YW-107);the China Postdoctoral Science Foundation to Benxun Su

摘　　要：Early Permian mafic-ultramafic complexes in eastern Xinjiang （新疆） are mainly distributed in the Beishan （北山） area, Mid-Tianshan （天山） massif and Jueluotage （觉罗塔塔） belt. Systematic compositional mapping of olivines from these Early Permian mafic-ultramafic complexes demonstrates that an apparently spatial distribution and heterogeneous partial melting in the mantle source exists from the Beishan area, across the Mid-Tianshan massif, to the Jueluotage belt from the south to the north. This is probably consistent with the spatial evolutional differences and tectonic features of these three belts. The decreasing degree of partial melting, as revealed by decreasing Fo contents of olivines, from south to north and from east to west reflects the southward subduction of the Paleo-Asian Ocean and the south location of the indistinct mantle plume in the Permian. Simultan ously, NiO and Fo-mapping in olivine also indicates that sulfide segregation before olivine crystallization played an important role in Ni-Cu mineralization in the mafic-ultramafic complexes. Olivines with the compositional range of Fo （77-86） and NiO （less than 0.22 wt.%） are more favorable for Ni-Cu sulfide mineralization.Early Permian mafic-ultramafic complexes in eastern Xinjiang （新疆） are mainly distributed in the Beishan （北山） area, Mid-Tianshan （天山） massif and Jueluotage （觉罗塔塔） belt. Systematic compositional mapping of olivines from these Early Permian mafic-ultramafic complexes demonstrates that an apparently spatial distribution and heterogeneous partial melting in the mantle source exists from the Beishan area, across the Mid-Tianshan massif, to the Jueluotage belt from the south to the north. This is probably consistent with the spatial evolutional differences and tectonic features of these three belts. The decreasing degree of partial melting, as revealed by decreasing Fo contents of olivines, from south to north and from east to west reflects the southward subduction of the Paleo-Asian Ocean and the south location of the indistinct mantle plume in the Permian. Simultan ously, NiO and Fo-mapping in olivine also indicates that sulfide segregation before olivine crystallization played an important role in Ni-Cu mineralization in the mafic-ultramafic complexes. Olivines with the compositional range of Fo （77-86） and NiO （less than 0.22 wt.%） are more favorable for Ni-Cu sulfide mineralization.

关 键 词：mafic-ultramafic complex oli-vine compositional mapping Ni-Cu sulfide min-eralization Beishan Mid-Tianshan massif Jue-luotage belt. 

分 类 号：P597.3[天文地球—地球化学]