Submarine channel and lobe hidden inside mass-transport deposits in the northern Gulf of Mexico

Despite numerous subsurface studies of mass-transport deposits (MTDs) using seismic data, internal characters of MTDs at the seismic scale are still not well understood, largely because of the limitation of seismic resolution. This study investigates Miocene-Pliocene MTDs in an understudied, hydrocarbon-rich region of the northern Gulf of Mexico. With the help of quantitative seismic geomorphology techniques, we utilized a high-quality 3D seismic dataset. We document sinuous channel and lobe features hidden within individual MTDs. This provides evidence for considering a seismically-defined MTD unit as amalgamated deposits of multiple events with different flow types (e.g., turbidity currents and cohesive flows), rather than an en masse deposit of a singular event. Additionally, we document an unshielded erosional remnant, which is generated by the bifurcation of a megascour marking the base of an MTD unit. Remnant strata are interpreted as sandy sediment waves. Channel, lobe, and erosional remnant features examined in this study demonstrate the presence of reservoir-prone facies encased within MTD units, forming stratigraphic traps. This research enhances our understanding of the intermingling nature of MTDs and other typical deep-water deposits, and the reservoir potential of MTDs and associated strata.