This joint project aims to better understand continental breakup, factors influencing mantle exhumation and processes in the rift to drift transition at the ContinentOcean Transition (COT) through a comparative study of the South China Sea (SCS) and the West Iberian (WI) continental margins. In the SCS, a multichannel seismic reflection survey with deployment of ocean bottom seismometers will be acquired to better image the complex structures of the COT. In WI a set of deep multichannel seismic reflection lines representative of the margin will be prestack migrated and combined with wideangle/refraction and potential field data, followed by numerical lithospheric modeling constrained by ODP/IODP drilling results to better image and constrain the lithospheric structure at the COT. The successful implementation of this project will facilitate postcruise studies of new IODP Expeditions in the SCS and strengthen the collaboration between the two research groups from China and Portugal.