Deposition and Dynamics of Overbank Flow from Submarine Channels

Ian Kane, University of Leeds, Department of Earth Sciences, Leeds, UK, [email protected]

As a response to overbank flow removing both fluid and sediment from a turbidity current, through-channel flow will continuously evolve with increasing distance down-channel. In an aggradational system, levees will build along the outer banks of the channel with each turbidity current passing through the system potentially leaving a record on the levee flanks. In a bypassing system levees may be the only record of the passage of turbidity currents. This study aims to elucidate the key controls on overbank flow and deposition by taking an experimental and field-based approach. In the lab, various parameters of overbank and through-channel flow will be recorded using ultrasonic velocity profilers; sediment concentrations will be assessed using at-a-point siphon sampling; both of these can be done simultaneously within various channel models. Because they commonly form on oceanic or transitional crust, large scale, aggradational channel-levee sequences are poorly preserved in the continental rock record. The project will focus on one such system which is reliably identified, the Upper Cretaceous Rosario Formation in Baja California, Mexico. The principal aim in the field will be to document spatial trends in bed thickness and grainsize distribution within correlated packages along transects away from the channel axis. Analysis of grain size and bed-thickness data may elucidate the character of the flows which deposited these levees.

The project will potentially offer new insights into overbank flow and deposition from submarine channels with important consequences for academia and the hydrocarbon industry alike.