GEOLOGICAL EVOLUTION OF THREE RIFTED CONTINENTAL MARGINS IN THE AMERICAS (ALASKA, BRAZIL, CANADA)

This dissertation concerns the analysis of rifted continental margin sedimentary basins. The primary database consists of seismic reflection profiles and petroleum exploration well data. Special emphasis has been placed on attempting to understand the geological evolution of the sedimentary basins. The work is presented as a series of five papers covering three study areas in the Americas.;The fifth paper investigates the age and significance of the regional unconformities on the three Jurassic/Early Cretaceous rifted continental margins. Evidence is presented which shows that the regional unconformities developed at times of major change in basin geometry representing, for example, the transition from active rifting to passive thermal subsidence. Hence, the unconformities formed by processes active within each basin and not due to interaction with external forces such as global sea level. Several of the major changes in basin geometry occurred at similar, but not identical, times on these three, widely spaced rifted continental margins.;One paper sets out the study method and describes depositional sequence mapping as a technique to establish tectonic and stratigraphic framework and evaluate hydrocarbon potential on a passive continental margin. Three papers are case histories, which cover study areas of increasing structural and stratigraphic complexity. The study areas are the Santos Basin offshore Brazil; the Grand Banks offshore eastern Canada and the Beaufort Sea region of north Alaska and northwest Canada. Depositional sequence mapping is used to analyze the geological evolution and hydrocarbon habitat of each region.