Numerical Models of Turbidite Distribution in Submarine Diapirically Controlled Settings

Complex seafloor topography, such as salt-induced topographies on passive continental margins, plays a significant role in controlling turbidity current behavior and sediment dispersal patterns. One method to investigate the interaction of sediment gravity currents and topography is the use of process-based numerical simulations. Potential topographical templates can be generated from laboratory analogue experiments or can be directly obtained from 3D bathymetry data.

In the present study we adopt the above two sets of topographical seafloor data, experimental topographies and high-resolution surfaces from areas of the present-day seabed, where there is evidence of near-bed salt or mud diapirism and withdrawal. These inputs not only provide both experimental and 'real-world' templates to investigate the extent these topographies affect flow character, routing and the resulting deposit geometry, but also offer a perspective on the validation of the experimental method by comparison among a variety of results.

The input parameters for flow simulation consist of those defining the initial topography as well as parameters related to the composition of the flows (grain size range, concentrations, magnitude and frequency). To simulate natural subaqueous density flows, a range of parameter combinations (flow volume, height, input velocity, frequency) has been chosen within the appropriate ranges expected to occur in nature.

A particular focus is placed on the degree of effective confinement of obstacles and the deposit filling patterns in sub-basins bounded by salt walls and ridges. The present results suggest that for the continuous flow passing over the obstacle as well as the deflected flow to the sides of the obstacle, significant deposition occurs on the counterslopes after topographic lows. This shifts the topographic lows upstream and tends to favor backfilling in that direction with a trend of fining- and thinning-upward successions. The results provide basic and conceptual insights into flow/deposit/topography interactions, which continue to be a major interest for the exploration and production of oil and gas reservoirs in such settings. In the future, they will be validated with high-resolution field data.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California