Sixty million years of carbonate deposition were simulated to test an interpretation of platform development based on seismic data and limited well control from northwestern Great Bahama Bank. Seismic profiles of the northwestern Great Bahama Bank document the lateral growth potential of isolated platforms that were welded together by progradation to form the modern bank. The mechanism we proposed responsible for an evolution from aggradation to progradation was sediment overproduction on the platform, the excess of which was transported offbank and which caused a decrease in accommodation space on the marginal slope. Progradation occurred in pulses that were interpreted to be the result of third-order sea level fluctuations. To evaluate the proposed mechanism, 15 input p rameters were used to model the platform evolution.

The simulation program, which uses empirical relationships to model basin fill, successfully reproduced the geometries seen on the seismic lines, indicating that the proposed interplay of mechanisms could have built the observed platform architecture. The simulation demonstrated, in particular, that in a setting like the Bahamas, a basin must be substantially filled before progradation can take place, and that sea level changes can drive the pulses of progradation. This implies that laterally stacked sequences often contain the record of sea level changes, and therefore have potential use in sequence stratigraphy.

The simulation can also be used to estimate the quantitative importance of individual factors controlling aggradation and progradation in the Bahamas. We show how close the balance between aggradation and progradation is, and how small changes in the rate of subsidence or accumulation can cause immediate switches from aggradation to progradation. In particular, we show that the rate of subsidence exerts the major control on the timing of progradation, more so than basin width. Carbonate production rates similar to modern rates were required to produce the necessary sediment input for progradation, which suggests that carbonate production has been consistently high since the early Tertiary. Repeated exposure and erosion, however, have decreased the overall accumulation rate. The simula ion also suggests that the asymmetric progradation in the Bahamas was only possible where there were extreme differences between windward and leeward conditions, with a maximum sediment input of 10% from the windward side.