Application of computer simulation to sequence stratigraphic interpretations

This dissertation describes a series of studies that combine the principles of seismic sequence stratigraphy with the techniques of computer simulation. The first study was to test the hypothesis that given a steady subsidence rate in an area for several sea level cycles, if the sequence geometries of a sedimentary simulation generated with the eustatic sea level match those interpreted on seismic lines from that area, then the ages of these later sequences are similar to the former. The Haq et al. (1987) sea level cycle chart updated for the Neogene with the absolute ages provided by Berggren et al. (1995) was used. Sections from the Straits of Andros in the Bahamas, the NW Shelf of Australia and the Maldives Archipelago were used for these studies. The Early Neogene fills of these different regions were assumed to have accumulated in uncomplicated and uniform tectonic settings. This simplified the inputs to the simulation, which then focused on capturing the sedimentary response to the eustatic changes. The subsequent graphical output shows a good match to the interpreted seismic and validated the hypothesis. It also established that for areas of known subsidence, simulation techniques could be used to date seismic sections where biostratigraphic data is poor. For the second study, the growth of the Niagaran (Middle Silurian) pinnacle reefs of northern Michigan and their encasement by the lower Salina Group (Upper Silurian) A-1 and A-2 evaporate-carbonate cycles was modeled. Various working hypotheses were investigated with the simulation, including the effect on the evolution of the reefs, the configuration of the initial basin floor, the history of subsidence, sea level fluctuations and evaporite-carbonate depositional patterns. The simulation successfully reconstructed the dimensions, geometry, and relationship of the various units within the prescribed geologic time frame, supporting a model of evaporite drawdown and establishing a potential range for the quantitative attributes of the controlling factors. Finally a review was assembled of first generation of two-dimensional simulations of depositional systems that were researched as part of the overall dissertation.