WU Jie¹, LIU Jia-jun¹, WANG Jian-ping¹, YANG Long-bo¹, LIU Chong-hao¹, WANG Wei-yu², WANG Li-xin², YU Kang-wei², LI Zhi-guo³

1. State Key Laboratory of Geological Processes and Mineral Resources School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China;
2. Huachanggou Gold Mine of Lueyang County in Shaanxi Province, Lueyang 724312, China;
3. China Gold Group Corporation, Beijing 100011, China

Abstract: The spilite is one of the main host rocks in the Huachanggou gold deposit. On the basis of detailed field geological survey and systematic laboratory study including microscope observation, electron probe scanning, major and trace element analysis, this article studied petrological and element geochemical characteristics of spilites. The result showed that two typical altered mineral assemblages of spilite are albite+chlorite+epidote±actinolite and albite+Fe-dolomite+sericite, and that the spilite samples fall into tholeiitic basalt series and basaltic trachyandesite areas in the TAS diagram of effusive rocks, having low REE content (27.53×10-6-58.46×10-6), low enrichment in LREE[the average value of(La/YbNis 1.24)] , and a flat REE pattern. The analysis of stable high field-strength elements (HFSE) suggested the splite was formed in an extentional setting, and possibly originated from a primitive spinel-lherzolite stability field above asthenosphere mantle. Crustal contamination also contributed significantly to the formation of the spilite. It can be inferred that the spilite was formed in the early stage of the development of the Mianlue ocean in the Middle Devonian.

Keywords: petrology elemental geochemistry genesis of spilite Huachanggou gold deposit