Stratigraphic modelling of platform architecture and carbonate production: a Messinian case study (Sorbas Basin, SE Spain)

The late Messinian mixed carbonate-siliciclastic platforms of the Sorbas Basin, known as the Terminal Carbonate Complex, record significant changes in carbonate production and geometry. Their facies and stratigraphic architecture result from complex interactions between base-level fluctuations, evaporite deformation/dissolution and detrital inputs. A 3D quantitative approach (with DIONISOS software) is used to explore the basin-scale platform architecture and to quantify the carbonate production of the Terminal Carbonate Complex. The modelling strategy consists in integrating detailed 2D field-based transects and modern carbonate system parameters (e.g. carbonate production rates, bathymetric and hydrodynamic ranges of production). This approach limits user impact and so provides more objective output results. Tests are carried out on carbonate production rates, subsidence and evaporite deformation/dissolution. Numerical modelling provides accurate predictions of geometries, facies distributions and depositional sequence thicknesses, validated by field data. Comparative statistical testing of the field transects and of the various model outputs are used to discern the relative contribution of the parameters tested to the evolution of basin filling. The 3D visualization and quantification of the main carbonate producers (ooids and microbialites) are discussed in terms of changes in base-level and detrital supply. This study demonstrates that base-level fluctuations have the greatest impact on the carbonate budget. Evaporite deformation/dissolution affects the type and amount of carbonate production, inducing a transition from an ooid- to microbialite-dominated system and also has a major effect on stratigraphic architecture by inducing the migration of depocentres. The numerical modelling results obtained using modern carbonate system parameters could also be applied to subsurface ooid-microbialite reservoirs, and the Terminal Carbonate Complex is a good analogue for such systems.