Intermingled fates of the South China Sea and Philippine Sea plate

Recent studies have shown the extent and nature of the South China Sea (SCS) at the end of spreading by unfolding (i.e. structurally restoring) the Manila slab, which is the subducted part of the SCS, and by identifying the nature of the crust-lithosphere (oceanic or thinned continental) from mid-slab P-wave velocity perturbations (dVp) [1,2]. The objective of this paper is to propose a reconstruction of the SCS at the end of seafloor spreading and to discuss its geodynamic consequences in the context of the SCS and Philippine Sea plate (PSP) evolution. Reasonably accurate PSP paleo-latitudes and poorly defined paleo-declinations were primarily used to establish the kinematic evolution of the PSP through time (e.g. [3,4]) until 2016, when Wu et al. [1] introduced new kinematic constraints based on the unfolding and restoration of Southeast Asian slabs. Here, we propose to better constrain the relationship between the SCS, the Huatung basin (HB) and the PSP. Our main target is to bring new light on the challenging problem of SCS subduction initiation along a major shear-plate boundary. For that, we build on the new kinematic constraints provided by Wu et al. [1] and consider that the HB was not formed during Tertiary (e.g. [5,6]), but during the early Cretaceous (e.g. [7])