Spilling into confinement: Submarine canyon-confined overbank processes and architecture

Submarine canyon-confined overbanks comprise substantial volumes of thin-bedded sediment gravity flow deposits that were either stripped or overspilled from adjacent channels and offer more complete records of canyon evolution than axial deposits. The Punta Baja Formation, Mexico, comprises a rare exhumed canyon fill with kilometer-scale dip and strike exposures that permit detailed documentation by high-resolution sedimentary logging and photogrammetric models. The lower overbank is characterized by laterally variable sandstone bed thicknesses and grain sizes, indicating that turbulent flows of varying magnitudes overspilled from channels. Thick sandstone beds contain paleocurrent indicator reversals and hummock-like bedforms, representing high-energy combined flows that deflected and reflected against the canyon margin. In the upper overbank, as the canyon fill aggraded and widened …