Although eolian facies models have been developed since the 1970s, only recently have they become sufficiently sophisticated to enable the effects of external climatic and tectonic controls to be expressed in terms of resultant facies architecture. By using a joint conceptual and process-based approach, the response of eolian systems to changes in controlling parameters such as sediment supply, sediment availability, water table, and wind regime is now well understood. Dynamic facies models are able to account for spatial and temporal variations in these controlling parameters and predict likely stratigraphic responses. Large-scale, quantitative stratigraphic data sets from outcrop are being applied to unequivocally demonstrate relationships between preserved eolian architecture and original bedform morphology and migratory behavior.
In dry eolian systems, the key to developing predictive facies models has been an appreciation of the paleoenvironmental significance of the 3D geometry and hierarchical nature of bounding surfaces, which has enabled the products of external (allocyclic) controls such as climate change be discerned from the complex mechanics of intrinsic (autocyclic) bedform migratory behavior. In wet eolian systems, subtle variations in interdune architecture provide the basis for a spectrum of predictive facies models that explain preserved eolian architecture in terms of interactions between water-table level, sediment availability, dune size, and dune migration rate, parameters which in turn are a function of sediment distribution pathways, climate, and basin setting.
The development of eolian facies models is important for understanding the likely response of desert systems to climatic and environmental change. Additionally, predictive models remain important for hydrocarbon exploration, particularly in mature provinces, where good well control allows the employment of sophisticated models in the search for small plays based on subtle stratigraphic traps.
Figures & Tables
Facies Models Revisited
Conference of the Canadian Society of Petroleum Geologists) and in Dallas in 2004 (Annual Conference of the American Association of Petroleum Geologists). These sessions, entitled Facies Models Revisited, were intended to capture the state of the art with respect to facies modeling in several key depositional environments. This volume is focused on clastic depositional settings including continental (aeolian and fluvial), estuarine, shoreface, deltaic, shelf, and deep water. The approach that they encouraged with the authors to follow was a first-principles rather than a model-driven approach. Their philosophy was to provide the reader with the tools and rules to create their own models rather than providing them with “canned” models or “templates”. Following this approach, they believe that geoscientists will develop better and more predictive facies of depositional models. The editors believe this volume will find a niche with both academic as well as industry and government geoscientists.