Linking Dune Dynamics to Facies Heterogeneity in Preserved Aeolian Systems

Aeolian sedimentary systems record past climate changes due to their sensitivity to environmental variables, such as changing rates of sediment supply, climate, wind regime and palaeoflow, the action of physical, chemical and biogenic stabilising agents, and also interactions with other coeval sedimentary systems. Due to the interplay of allogenic and autogenic controls, the preserved sedimentary record of aeolian systems is highly complex and exhibits a variety of sedimentary architectures and spatial heterogeneities in facies distributions. Meanwhile, the accumulated deposits of aeolian sedimentary successions form important potential subsurface geothermal reservoirs and underground repositories for large-scale carbon capture and storage in both depleted and repurposed hydrocarbon reservoirs, and in very large saline aquifer bodies. In this study, a novel rule-based forward stratigraphic model, the Dune Architecture and Sediment Heterogeneity model (DASH), is used to investigate the variations in facies heterogeneity across different types of dunes, taking into account their sizes, migration rates, and aggradation rates over a broad spectrum of temporal scales. The DASH model is a geometric-based model that can reproduce different hierarchies of sedimentary architectures and bounding surfaces of aeolian dune and interdune and fluvial dune, barform and sheet-like deposits. The modelling outputs will enable more accurate predictions and systematic analysis of facies spatial distributions in different aeolian systems, including transverse dunes, linear dunes, and superimposed dunes. The modelling outputs can further be employed for predictions of petrophysical heterogeneity, for example, to guide models to assess geothermal reservoir potential and to model carbon capture and storage scenarios.