Geochemical variation of volcanic rocks from the South China Sea and neighboring land：Implication for magmatic process and mantle structure

摘要

Geochemical study of Kon Tum (KT) plateau, Sanshui (SS) basin and Daimao (DM) seamount volcanic rocks provides new insight into magmatic processes and characteristics of the mantle source beneath the South China Sea (SCS) basin and its surroundings. Geological signature of basaltic lavas from KT, SS and DM indicate rather than a deep-rooted plume derived from the core-mantle boundary, a shallower mantle domain, such as sub-continental lithosphere mantle or asthenospheric mantle, is more likely to be the mantle source region beneath the SCS basin and its adjacent areas. The mantle source beneath the SCS basin has been shown to be more depleted relative to the source regions of the SS basin and the KT plateau, indicating that the magmatism in the SS basin has been interrupted due to the SCS spreading and then recovered in the KT plateau area. The mantle heterogeneity has been sampled and an enriched component that is geochemically comparable to EM2 endmember has been identified in the mantle source region of the SCS basin and its surroundings. This EM2 component was formed by the recycling of Mesozoic subducted proto-SCS slab along with terrigenous sediments.