Abstract

Understanding and predicting architecture and facies distribution of syn-rift carbonates is challenging owing to complex control by climatic, tectonic, biological and sedimentological factors. CarboCAT is a three-dimensional stratigraphic forward model of carbonate and mixed carbonate–siliciclastic systems that has recently been developed to include processes controlling carbonate platform development in extensional settings. CarboCAT has been used here to perform numerical experiment investigations of the various processes and factors hypothesized to control syn-rift carbonates sedimentation. Models representing three tectonic scenarios have been calculated and investigated, to characterize facies distribution and architecture of carbonate platforms developed on half-grabens, horsts and transfer zones. For each forward stratigraphic model, forward seismic models have also been calculated, so that modelled stratal geometries presented as synthetic seismic images can be directly compared with seismic images of subsurface carbonate strata. The CarboCAT models and synthetic seismic images corroborate many elements of the existing syn-rift and early-post-rift conceptual model, but also expand these models by describing how platform architecture and spatial facies distributions vary along-strike between hanging-wall, footwall and transfer zone settings. Synthetic seismic images show how platform margins may appear in seismic data, showing significant differences in overall seismic character between prograding and backstepping stacking patterns.