A Turbidity-Current Model to Simulate Impact of Basin-Scale Forcing Parameters
Published:January 01, 2009
T. Salles, S. Lopez, R. Eschard, T. Mulder, T. Euzen, M.-C. Cacas, 2009. "A Turbidity-Current Model to Simulate Impact of Basin-Scale Forcing Parameters", External Controls on Deep-Water Depositional Systems, Ben Kneller, Ole J. Martinsen, Bill McCaffrey
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A numerical model was developed to simulate sedimentary architectures created by turbidity currents over geological time. The model is based on the cellular automata paradigm. The automata exchange matter and energy and are built to reproduce the physical processes which govern turbidity-current behavior. The simulated architecture is the result of a given set of geological events. For each of these events a steady state is computed. This steady state is assumed to be representative of the average effect of a turbidity current on the construction of the sedimentary architecture. Using the model, we studied the impact of external controls on deep-water depositional systems. Topographic control on geological deposits is studied using various slopes. Several architectures are also reproduced thanks to spatial and temporal variations in the frequency and magnitude of the turbidity-current events. The role of suspended-sediment concentration and grain-size distribution on the transport efficiency are presented. The model results show that small variations of flow inputs may have strong controls on deposit evolution. This numerical approach allows a better identification and understanding of key physical parameters and may provide a better prediction of reservoir architecture in deep-sea clastic systems.
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External Controls on Deep-Water Depositional Systems
The principal objective of the meeting from which this set of papers arose was to gain an overview of the current state of knowledge of the roles and interplays of external controls on deposition in deep marine environments. By external controls we mean allocyclic or allogenic factors, i.e., those that are unrelated to the self-organization of the depositional system (autocyclic or autogenic); principal among these are climate, sea level, sediment supply, and tectonics. One of the big questions that the meeting sought to address concerned the comparability of the recent high-frequency, high-resolution record with the older, generally lower-frequency stratigraphic record of “deep time”; to what extent are the apparent differences a function of resolution, or of comparisons between a glacial and a nonglacial Earth? In fact, as the papers in this volume illustrate, the variability between individual systems, even in Late Glacial time, and the paucity of constraints on older systems makes these questions difficult to answer, but some useful conclusions can be drawn. The papers presented at the meeting were organized into themes that included: overviews of glacial sea-level change, and of climate modeling; external controls on large river-fed submarine fans, including the effects of climate and sea level on the fluvial system itself; influences of climate, sea level, and tectonics on a range of smaller modern systems; deep marine processes; the outcrop record of the pre-Pleistocene Earth; the subsurface record of the pre-Pleistocene Earth; and syntheses. The organization of the volume largely reflects this structure.