Trace Elements in Olivines from the Giant Jinchuan Ni-Cu-(PGE) Deposit,NW China,and Its Geological Implication
Kang Jian;Chen Liemeng;Song Xieyan;Dai Zhihui;Zheng Wenqin;State Key Laboratory of Ore Deposit Geochemistry,Institude of Geochemistry,Chinese Academy of Sciences;University of Chinese Academy of Sciences;
The giant Jinchuan magmatic sulfide deposit in China is the third largest mining deposits in the world. Although many research have been done,there still exist some debates in the genesis of deposit. This study using the LA-IC-MS to obtain the trace elements concentrations of the olivine in order to discuss the mechanism of influence the element variability and illustrate the process of magmatism and ore-forming. The analytical results show that Ni,Co correlate negatively with Fo in the olivine,Mn/Fe is positively correlate with Fo,while Mn/Zn and Zn/Fe show no obvious correlation with Fo. The primitive mantle olivine-normalized trace element patterns of the Jinchuan olivine show that Jinchuan Ⅰ,Ⅱ intrusions have the same trace elements characteristics,which display negative Cr,V,Ni,Co and Ti anomalies and enrichment of Zr,Y,Ti,Sc and Ca. The multi-element patterns of the Jinchuan olivine imply same parental magma in the intrusion Ⅰ and Ⅱ. The spinel which cocrystallization with the olivine make it display negative Cr,V and Ti anomalies. The contents of Ni and Co in olivine are influenced by the process of sulfide segregation and the reaction between sulfide and olivine. The lower content of Cr and V in olivine of the intrusion Ⅱ compared with the intrusion Ⅰ imply that the parental magma of the intrusion Ⅱ was more evolved. Higher Mn/Zn(13)ratios and lower Zn/Fe(11)ratios indicate that the magma of Jinchuan intrusion likely originate from partial melting of peridotite mantle possibly,instead of pyroxene mantle sources.