Evolution of Intraplate Alkaline to Tholeiitic Basalts via Interaction Between Carbonated Melt and Lithospheric Mantle

Abstract Intraplate basaltic volcanism commonly exhibits wide compositional ranges from silica-undersaturated alkaline basalts to silica-saturated tholeiitic basalts. Possible mechanisms for the transition involve variable degrees of partial melting a same source, decompression at different mantle depths (so-called ‘lid effect’), and melt-peridotite interaction. To discriminate between these mechanisms, here we investigated major-trace elemental Sr–Nd–Mg–Zn isotopic compositions suite intraplate Datong volcanic field in eastern China. Specifically, employed Mg Zn isotope systematics assess whether melts originated carbonated source. The have young HIMU-like Sr Nd compositions, lower δ26Mg (-0·42‰ -0·38‰) higher δ66Zn (0·40‰ 0·46‰) values relative mantle. These characteristics were attributable an asthenospheric source hybridized by derived stagnant Pacific slab zone. From basalts, gradually increases -0·42‰ -0·28‰ decreases 0·46‰ 0·28‰ with decreasing alkalinity incompatible trace element abundances (e.g. Rb, Nb, Th Zr). variations are significantly beyond magnitude (<0·1‰) induced fractional crystallization excluding magmatic differentiation, effect’ as possible accounting There strong, near-linear correlations 87Sr/86Sr (R2=0·75 − 0·81) 143Nd/144Nd (R2=0·83 0·90), suggesting additional This is characterized pristine mantle-like well EM1-like Sr–Nd ratios, pointing towards metasomatized subcontinental lithospheric (SCLM). Isotope mixing models show that mingling SCLM imparts all above correlations, which means must been partially melted during melt-SCLM reaction. Our results underline interaction acts one major processes leading diversity intracontinental volcanism.