Mass Transport Deposits and Slope Accommodation

Ben Kneller¹ and Mason Dykstra^2
1 University of Aberdeen, Aberdeen, United Kingdom
² University of California, Santa Barbara, CA

Mass-transport deposits (MTDs) comprise a large proportion of the sediments on the slopes and floors of deep water basins. These deposits range from a few m3 to greater than 5,500 km3 in volume, and thus include the largest sedimentation events on Earth. Depositional systems on the shelf, slope, and basin floor are affected by mass-flows by the destruction and creation of accommodation space, which alters sediment pathways and zones of deposition, bypass, and erosion. Accommodation space is created and destroyed by mass-transport processes in a variety of ways. Firstly, accommodation space is created in the slide scar area by removal of the sediment involved in the mass flow. Secondly, fully or partially ponded accommodation space is created updip of, and lateral to MTDs, due to the topographic relief they create on the seafloor. Thirdly, accommodation space is created by topographic relief on the surface of MTDs. The amount of relief present in each of these cases depends on the cohesion and rheology of the mass-flow, and can vary greatly within a single flow. Lastly, very large volumes of space can be created and destroyed by isostatic readjustment of the lithosphere due to the removal or emplacement of material on the surface of the Earth.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005