Late Miocene-Quaternary seismic stratigraphic responses to tectonic and climatic changes at the northeastern margin of the South China Sea

Tectonic and climate evolution could be well archived in deep-water stratigraphy. Based on newly acquired high-resolution two-dimensional (2-D) multichannel seismic profiles and multibeam bathymetry, together with Ocean Drilling Program/International Ocean Discovery Program (ODP/IODP) data, this study investigated the late Miocene-Qua-ternary deep-water seismic stratigraphy, sedimentary evolution, and responses to re-gional tectonic and climatic variations at the northeastern margin of the South China Sea. The late Miocene-Quaternary stratigraphy consists of three units (i.e., SU-1, SU-2, and SU-3 from bottom to top) that are dated to 10.5-6.5 Ma (stage 1), 6.5-0.9 Ma (stage 2), and 0.9 Ma-present (stage 3), respectively. SU-1 is dominated by sheeted drifts with slight thickness variation, but SU-2 and SU-3 mainly consist of mounded, lenticular con-tourite drifts and channel-like moats. This suggests that the bottom currents intensified from stage 1 to stage 2, which was probably caused by the sill uplifting at the Luzon Strait under the influence of tectonic collision be-tween the Luzon arc and Eurasia since ca. 6.5 Ma. SU-2 and SU-3 are separated by a basinwide high-amplitude seismic reflection, across which the average sedimentation rate shows a dramatic increase from -28 m/m.y. in SU-2 to -144 m/m.y. in SU-3. The high sediment supply since 0.9 Ma could be linked to the mid-Pleistocene climate transition, which resulted in abundant rainfall that promoted the Taiwan orogen to contribute more sediments to the South China Sea. This study indicates that the deep-water stratigraphy recorded the tectonic collision around the sole deep-water gateway (i.e., Luzon Strait) and mid-Pleistocene climate transition event at the northeastern South China Sea margin, which has important implications for under-standing the relationships among the tectonic, paleoclimatic, paleoceanographic, and deep -water sedimentary processes in the largest marginal basin of the western Pacific Ocean.