Deciphering Equatorial Pacific Deep-Sea Sediment Transport Regimes by Core-Log-Seismic Integration

Understanding deep-sea sediment transportation and deposition regimes is a key to accurately evaluate paleoceanographic implications recorded by pelagic sediments. However, investigating the movement of deep-sea pelagic sediments over time has been a challenging task due to the complexity of sediment redistribution processes, which often requires the combination of multidisciplinary methods. To comprehensively characterize the three dimensionality and temporal evolution of pelagic sediment redistribution, we conduct the first integration of multichannel seismic reflection data in the Pacific Equatorial Age Transect 7 and 8 surveys, with downhole geophysical logging data from two Integrated Ocean Drilling Program Sites, U1337 and U1338 as well as ^230Th flux measurements. Our seismic analysis at Site U1337 (PEAT 7) and Site U1338 (PEAT 8) areas show that distinct degrees of sediment focusing are occurring at the two sites, indicating that each site is experiencing different sediment redistribution processes (i.e., basin fill vs pelagic drape). In these sites, sediment focusing (i.e., infilling of basins due to lateral syndepositional sediment redistribution) is observed to be primarily a result of differences in sediment supply and the interaction between seafloor topography and deep-sea currents. To verify and test the temporal resolution at which seismic data can characterize lateral sediment redistribution, we compared our focusing factor results against ^230Th-derived focusing factors specifically at PEAT 7 area. Our comparison of focusing factors demonstrated that both methods yield accurate sediment flux estimates that are directly supported by the observed pelagic environment, in this part of the equatorial Pacific. The results from our integrative approach further prove that pelagic environments are far from “quiescent”, confirming that we successfully demonstrate the complex and dynamic nature of deep-sea pelagic sedimentation and sediment redistribution that occurs at distinct regional and temporal scales