Mg isotopic compositions of post-spreading lavas in the South China Sea

Abstract

Post-spreading Cenozoic lavas from the South China Sea (SCS) region record some important information about the nature of underlying mantle source and deep mantle processes. In this study we analyzed Mg isotopic compositions of the post-spreading lavas collected in the SCS region. The data, together with bulk-rock major and trace element compositional data, and radiogenic isotopic data were used to indicate the origin of post-spreading volcanism distributed in the SCS region and deep geodynamical setting. We built a conceptual model for the magmatic process of post-spreading intraplate volcanism in the SCS region, and proposed that the thickness of lithosphere, as well as the involvement of recycled carbonate into their sources, are two of controlling factors for the variations of Mg isotopic compositions of lavas from the SCS region. (This study is supported by Taishan scholarship of Shandong province, Laoshan lab and NSFC).