Paleocene to Eocene deep-water slope canyons, western Gulf of Mexico: Further insights for the provenance of deep-water offshore Wilcox Group plays

Abstract

In the Gulf of Mexico (GOM), an extensive deep-water fan system of the lower Tertiary Wilcox Group forms a significant exploration target, yet connections to equivalent-aged onshore fluvial, deltaic, and shallow-marine reservoirs are poorly documented. Using a large, three-dimensional (3-D) seismic survey (3300 mi2, 8500 km2), we examined the lower Tertiary structure and stratigraphy of the underexplored Texas coastal zone, approximately 60 mi (96 km) downdip of the paleoshelf edge and 200 mi (322 km) updip of the deep-water discoveries. Canyons are identified throughout the inferred Paleocene to upper Eocene interval near Matagorda Bay, with this study focusing on the youngest. These are typically 2–2.5 mi (3–4 km) wide and 600–1600 ft (200–500 m) deep. Main incisional axes trend downslope, and some bifurcate. Early salt movement appears to have created an irregular paleoslope topography and an altered slope gradient, thereby influencing depositional flow pathways. In a paleogeographic context, this canyon complex is interpreted to lie in a middle- to lower-slope setting and sits directly downdip of the Wilcox Group shelf-margin canyon systems. Although not all of the canyons necessarily connect updip to the shelf-edge canyons, or downdip to fan systems, they represent part of a large-scale complex along this western GOM margin that acted as a conduit to the successfully drilled, deep-water, lower Tertiary Wilcox turbidite play. These results have importance not only for the prospectivity of the Texas shelf but also for the regional understanding of the Paleocene through lower Eocene paleogeography of the GOM.