Widespread Fluid Seepage Related to Buried Submarine Landslide Deposits in the Northwestern South China Sea

Abstract Fluid seepage sometimes impacts occurrences of submarine landslides, but the role of landslide deposits in fluid seepage is often neglected. Bathymetric data show that more than 1,000 seabed mounds are scattered over an elongated area at the shelf edge of the northwestern South China Sea. Vertical seismic pipes in the subsurface are spatially correlated with both surface mounds and buried landslide deposits. Detailed analyses within the three‐dimensional (3D) seismic survey show that at least 221 of 231 (∼96%) of the mounds have spatial correlation with the top edges of multiple stages of buried landslide scarps that are stepping seawards from deep to shallow, indicating a causal relationship between buried landslide deposits and fluid seepage. Fluids emitted via differential compaction and hydrofracturing in geological setting characterized by frequent tectonism, flowed upwards along shear surfaces and scarps of landslide deposits and pipes, and eventually provided hard substrates for mound building.