Modeling the processes that form and erode marine strata.

摘要

Numerical simulators of the dynamics of strata formation of continental margins fuse information from the atmosphere, ocean and regional geology. Such models can provide information for areas and times for which actual measurements are not available, or for when purely statistical estimates are not adequate by themselves. This dissertation develops two such models that are applied to Earth's continental shelves.; Sedflux is a whole margin model able to simulate the delivery of sediment and their accumulation over time scales of tens of thousands of years. The Sedflux model is extended to more realistically simulate the distributions of seafloor geotechnical parameters during the growth of a seismically active continental margin. The improved formulation better predicts the frequency, size, and location of sediment failures. Although the overall architecture is not significantly changed, the internal stratal organization is altered. Sediment failures are found to be most likely during falling or low sea-level conditions.; The Sedflux model is further extended by adding a series of new processes models, and extending the model environment to track the evolution of stratigraphy in either two or three dimensions. Additions to the 2D-mode include models that simulate (1) sediment erosion and deposition along a riverbed, (2) cross-shore transport due to ocean waves, and (3) turbidity currents and hyperpycnal flows. New processes in the 3D-mode include (1) river channel avulsion, (2) two-dimensional diffusion due to ocean storms, and (3) two-dimensional flexure due to sediment loading.; In contrast to the complex Sedflux model, a single-process model is developed that predicts the contribution of water loading to the subsidence of Earth's continental shelves. Based on a one-dimensional elastic flexure model, an analytic solution for the deflection of a linear slope, due to sea level rise and fall, is derived. This analytic solution allows a global database of deflection estimates for continental shelves, due only to increases in water loading, and the shape of the LGM continental margins. Thus, changes in eustatic sea level are disengaged from changes in relative sea level. Pleistocene variations in water loading can change the slopes of continental shelves on the order of 30%.