The evolution of continental margins and related distribution of hydrocarbon reservoirs in divergent margin basins reflects the primary interaction between sediment supply and process regime within the basin and secondary modifications by sea-level change and structural history. Cenozoic sequences of the northwestern Gulf Coast Basin contain numerous, highly explored hydrocarbon fairways that reflect typical productive styles resulting from progressively reduced influences of tectonic events in the North American plate and progressively increased influences of eustasy. Most Paleogene and lower Neogene sequences record moderate to high rates of sediment supply, locally enhanced load or salt-induced subsidence, and infrequent, relatively low-amplitude eustatic change. Accommodation space was created by crustal loading and gravity-driven continental margin extension or salt evacuation along with progradation into the deep-water gulf. Shorezone deposits are sand rich because slow or limited eustatic shoreline shift promoted effective reworking and shelfal storage of coastal facies. Progradational depocenters were characterized by large, long-lived, wave-reworked, shelf-edge delta systems; sands were largely stored close to the delta front and flanking shorezone systems. Prolonged periods of aggradation and retrogradation preserved thick, vertically stacked parasequences of deltaic and interdeltaic barrier/strandplain facies. Hydrocarbons accumulated in multiple, superimposed reservoirs primarily in mixed structurally and depositionally defined plays. In contrast, upper Neogene and Quaternary sequences are products of frequent high-amplitude eustatic cycles, rapid subsidence, and locally very high rates of sedimentation. Accommodation space was created by load-induced subsidence modified by salt evacuation and intermittent relative rises in sea level. Shorezone deposits are heterolithic because rapid subsidence and frequent eustatic shoreline shifts prevented extensive reworking. Progradational episodes were characterized by mud-rich, river-dominated shelf-edge deltas of moderate size. Rapid lowering of sea level promoted gravity remobilization of deltaic sediments and deposition of sand-rich lobes that created broad, structurally and bathymetrically complex submarine fans and slope aprons. Some sand-rich submarine fan lobes extend more than 160 km basinward from the paleoshelf margin, In contrast, strike reworking and sand storage on the shelf were minor. Combination structural and stratigraphic traps define most upper Neogene and Quaternary hydrocarbon plays. Correlating observed patterns of Cenozoic basin fill with contemporaneous plate interactions and eustatic fluctuations reveals the relative control of these variables on rates of sediment supply, characteristics of depositional sequences, and styles of basin-fill deformation.
