Geochemistry and petrogenesis of the Zaolin basanite in the northeastern Jiangxi Province

Two Cenozoic basanite dykes were newly discovered in the Zhuxi ore-concentration area, northeastern Jiangxi Province, eastern China. They have high SiO₂ (41.08%-42.94%), Na₂O+K₂O (4.95%-6.30%), TiO₂ (2.19%-2.43%) contents, and high Mg^# (0.61 -0.65). Geochemistry characteristics of these basanite dykes show they are enriched in Nb, Ta, Th, Zr, Ni, Cr, Sc, while depleted in Ba, Ti, K, and P. Their ∑REE values are from 299.16×10^-6 to 375.00×10^-6% with LREE/HREE ratios of 5.45-6.71 and δEu values of 0.88 to 0.94. According to the geochemical discrimination diagrams and the ratios of incompatible elements, we suggest that the basanite dykes were derived from partial melting of garnet forsterite (0.2%-0.5%) and herzolite (0.5%-1%), which may be caused by upwelling of carbonate melt in the asthenosphere mantle in response of the subduction of the Paleo-Pacific Ocean.