| Popis: |
The scale of submarine channels can rival or exceed those formed on land and they form many of the largest sedimentary deposits on Earth. Turbidity currents that carve submarine channels pose a major hazard to offshore cables and pipelines, and transport globally significant amounts of organic carbon. Alongside the primary channels, many systems also exhibit a range of headless channels, which often abruptly terminate at steep headscarps. These enigmatic features are widespread in lakes and ocean floors, either as branches off the main submarine channel thalweg or as isolated secondary channels. Prior research has proposed that headless channels may be associated with early and incipient stages of channel development, but their formation and evolution remain poorly understood. Here, we investigate the morphology, origin and development of headless channels by examining repeat bathymetric surveys spanning a period from 1986 to 2018, in Bute Inlet, Canada. We show how channel switching processes, the extension of turbidity currents across distal fans, along with overbanking turbidity currents, are able to initiate headless channels in submarine settings. We discuss how the evolution of headless channels plays an important role in shaping submarine channels, promoting channel extension and modifying the overall longitudinal profile, as well as impacting the character of sedimentary records in channel-lobe transition zones. |
