Mantle Heterogeneity and Melting Processes in the South China Sea: Thermal and Melting Models Constrained by Oceanic Crustal Thickness and Basalt Geochemistry

We simulate mantle flow, thermal structure, and melting processes beneath the ridge axis of South China Sea (SCS), combining nominally anhydrous fractional crystallization model, to study heterogeneity basin evolution. The model results are constrained by seismically determined crustal thickness major element composition fossil basalts. effects half-spreading rate, potential temperature, source composition, pattern melt migration on magma chemical systematically investigated. For SCS, east southwest (SW) subbasins have comparable thickness, but subbasin has higher FeO Na2O contents compared SW subbasin. estimated best fitting temperatures in 1,360 ± 15 °C 1,350 25 °C, respectively. (site U1431) prior cessation seafloor spreading is composed primarily depleted mid-ocean basalt (DMM), slightly contaminated eclogite/pyroxenite-rich component. However, (sites U1433 U1434) contains a small percentage (2–5%) lower continental crust. Basalt samples at northern margin U1500) shows similar characteristics with that suggest basin-scale variability SCS can be explained single which contamination crust gradually diluted DMM as moves away from rifted margin.