Taixinan contourite and mixed systems on the Gaoping slope: Influence of intermediate water masses on the Taixinan Canyon group

The Taixinan Basin, located in the northeastern South China Sea along the Taiwan orogenic belt, lies at the intersection between the passive and active margins of the Tainan and Gaoping slopes, where Quaternary deep-water sedimentation is modulated by both gravity-driven and bottom-current processes. This study integrates high-resolution gridded bathymetry, seasonal temperature and salinity fields, and selected multi-channel seismic profiles from the TAIGER and TAICRUST projects to investigate the spatial distribution and evolution of deep-water sedimentary systems. Seismic stratigraphic analysis reveals four Quaternary seismic units bounded by regional discontinuities. SUB represents Early Pleistocene syn-tectonic wedge-top basin fill deposited contemporaneously with thrust deformation and diapiric intrusion under active plate convergence. Above, SU1–SU3 record post-tectonic sedimentation, marking the establishment of the Taixinan contourite system as early as the Early Pleistocene. Contourite development is linked to bottom currents derived from two intermediate water masses—North Pacific Intermediate Water and South China Sea Intermediate Water—which flow eastward along the Tainan Slope before turning southward toward the Gaoping Slope. The Taixinan canyon group—comprising the Penghu, Shoushan, Gaoping, Kaohsiung, Fangliao, and Hongtsai canyons—formed primarily during the Late Pleistocene and constitutes the main sediment conduits along the Gaoping Slope. The interplay between gravity flows and bottom currents generated mixed turbidite–contourite deposits, defining the Taixinan mixed system. Three Quaternary morphosedimentary sectors—erosional, contourite depositional, and mixed depositional—are delineated, demonstrating the topographic control exerted by diapiric ridges on deep-water sedimentary processes. Future improvements require denser seismic survey coverage, integrated with detailed facies analysis and near-bottom oceanographic observations. • Quaternary Taixinan contourite and mixed systems across Tainan and Gaoping slopes . • Multi-channel seismic profiles from TAIGER and TAICRUST projects . • Early Pleistocene contourite system linked to intermediate water masses . • Late Pleistocene canyon-channel system records influence of gravity-flow processes . • Diapiric ridges control erosional and depositional morphosedimentary sectors.