Cellular Automata Modeling of Turbidity Currents Deposits

Salles, Tristan¹, Simon Lopez¹, Marie-Christine Cacas¹, Rémi Eschard¹, Euzen Tristan¹, Vanessa Teles¹, Thierry Mulder² (1) IFP, Rueil Malmaison, France (2) University Bordeaux I, Talence,

Using the cellular automata paradigm, we implemented a process-based model of multi-lithology submarine turbidity currents. It takes into account both gravitational and inertial effects when computing the flow over a given topography. It includes ambient fluid entrainment and lithology dependent erosion/deposition rules to progressively build a full three dimensional geological architecture. It produces sedimentary objects such as erosive channels, overflow levees, inner levees and depositional lobes with features such as facies partitioning and sediment sorting. This model was successfully validated against the deposits of a recent storm related turbiditic surge in the Bay of Biscay (France).

Moreover, in order to achieve an operational model over geological timescales, turbiditic deposits were considered to be the results of a succession of quasi steady-state events for which sediment transport had permanent values. In such a framework different spatial or temporal distributions of events may be seen as the consequence of varying climatic contexts and triggering processes. We observed that different sedimentary facies distributions and various 3D architectures resulted both from varying external controls (source location, flow energy, source sediment composition) and autocyclic phenomenon (topographic control through confinement and compensation effects).

Our work specially focused on sediment distribution in deep-water channels and possible reservoir implications as the predicted locations for sand, the net to gross ratios, the occurrence of permeability barriers... The model produces very realistic simulations that proved to be helpful tools to develop and to improve conceptual models.