HR: 1330h
AN: OS22A-1147    [PDF]
TI: Investigation of gravitational mass transport processes using numerical simulations
AU: * Huhn, K
EM: khuhn@uni-bremen.de
AF: Research Center Ocean Margins, PO Box 330440, Bremen, D-28334 Germany
AU: Kock, I
AF: Research Center Ocean Margins, PO Box 330440, Bremen, D-28334 Germany
AB: High-production regions, i.e. the NW African continental margin, are characterized by high sedimentation rates at upper slope. These materials are episodically transported down-slope in form of slides, debris flows, or turbidities. The main aim of our studies is to quantify the influence of different key parameters, i.e. material properties and geometrical settings, for deformation and kinematic behavior of gravitational mass transport processes. We use a numerical particle-based method - the Distinct Element Method (DEM) which has been proved to be an efficient tool to simulate geodynamical processes. This technique provides detailed information about mechanics and kinematics of down-slope processes, their mass transfer patterns, as well as internal and morphological structures. Furthermore, it enables a wide range of material parameters and model configurations to be tested. We develop a 3D DEM model which consists of a plane shelf, continental slope, and abyssal plain. Sediment layer is built up by spherical, elastic frictional particles which settle down under gravity on upper slope. We change iteratively the basal friction of slope surface as well as internal friction of sediments. Further model configurations are fixed. A decrease of basal and internal friction of sediments causes always an increase of run out length of the flow while thickness of depositions and lateral extension decrease. In addition, surface structures of lower slope change remarkable. Thus, we identified basal friction as important key parameter for spatial dimension and morphology of mass flow events. Nevertheless, we have to investigate the influence of model configurations in the face of transferability of model results into a natural system. Therefore, we developed a high-resolution 2D DEM model where (a) all spheres settle down under gravity in a triangular shaped box on upper slope. Removing box boundaries releases a gravitational mass flow. In experiment (b) all particles are settled under gravity on top of a shelf surface and they are transported progressively by a bulldozer to the upper slope. In both experiments, we observe a similar relationship between friction distribution and mass flow behavior. However, experiment settings (b) produce more natural process behavior.
DE: 3022 Marine sediments--processes and transport
DE: 3210 Modeling
DE: 4558 Sediment transport
DE: 8105 Continental margins and sedimentary basins
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting