Interaction of Turbidity Currents Traversing a Pockmark Field: Insights for Submarine Channel Inception

Abstract Pockmarks are widespread along continental margins and are commonly aligned in chains that may interact with turbidity currents. Although their potential role in initiating submarine channels has been proposed, the governing processes remain unclear. We use numerical simulations to examine how an initially gentle, subcritical turbidity currents interact with pockmarks and promote channel inception. As currents enter a pockmark, erosion localizes on the upper steep reaches of the upstream sidewall, driving sidewall retreat. Along the downstream wall, the gradually steep downstream sidewall make the flow generate reverse currents that propagate upstream and interact with the incoming current, producing deceleration, separation, and recirculating eddies. These reverse flows enhance sediment trapping on the pockmark floor. The coupled effects of upstream erosion and central infilling progressively reshape individual depressions and encourage partial coalescence of adjacent pockmarks, which organizes the emergence of incipient channels. With sustained input, erosion and deposition rates decline as the evolving morphology approaches a quasi‐steady state characterized by multiple recirculating eddies that separate intermittent near‐bed reverse flow from the steadier downstream current above. Our results show that relative moderate turbidity currents can opportunistically exploit pre‐existing pockmarks to nucleate channels, refining the mechanics of channel initiation and offering new insights into sediment routing and organic‐carbon burial in pockmark‐dominated deep‐water environments.