ZHANG Xiao-jing^1,2, XIAO Jia-fei¹
1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. University of Chinese Academy of Sciences, Beijing 100039, China

Abstract: To reveal whether or not Emeishan mantle plume had effects on Yufeng and Bama diabases, which locate at the southwest margin of the Yangtze block, this article tested major element contents, trace element abundances and ages of the diabases. The result showed that the diabases are calc-alkali or high potassium calc-alkali, characterized by high Al content and low Mg content, LREE-enriched, Ti/Y>500, Nb/La=0.75~0.85, Th/Ta=1.75~2.38, Ta/Hf>0.1. The LA-ICP-MS zircon U-Pb age results indicated that Yufeng and Bama diabases were erupted at 255.3±3.9 Ma and 257.6±2.9 Ma, respectively. We believe that they probably derived from depleted mantle with minor crust material contamination and belonged to continental intraplate basalts, and therefore, should be products of the Emeishan basaltic magma.

Keywords: geochemical Zircon U-Pb age zircon Hf isotope northwest Guangxi autonomous region Yangtze platform