Preliminary Test of a 3D Model for Carbonate Platform Sedimentation: Platform Response to Sea-Level Change and Variable Initial Seafloor Gradients

Understanding the impact of various depositional controls on the growth of carbonate platforms may help in predicting the continuity and spatial distribution of petroleum reservoir fades within ancient platform successions. This paper presents preliminary results from a 3D model for simulating the growth of carbonate platforms, focusing especially on the behavior of platform-margin fades tracts. The 3D model, described here for the first time, was used to investigate the impact of changing sea level on the growth of carbonate platforms, using a range of initial seafloor gradients. The initial depositional surface used in the model features an along-strike transition from gently dipping to more steeply dipping profiles. Simulations were performed to investigate different aspects of platform growth in response to a single cycle of sea-level change (200-meter amplitude, 200,000 yr cycle duration). Using low (∼1°) initial gradients, the model produces a complex depositional unit that consists of several detached platform-margin ‘terraces,’ each of which has a relatively low-relief final profile. Following the full cycle of sea-level change, the final depositional unit contains highly diachronous fades boundaries with significant fades dislocations. In contrast, using the same sea-level oscillation, but a steeper (∼16°) initial depositional gradient, the model creates a narrower platform, with a terminal depositional profile that is steeper overall. Internal chronostratigraphic relationships within the final depositional unit are also complex, although fades dislocations are more areally limited than in the low-gradient example.