Abstracts Category : Other

Linking Gulf of Mexico margin submarine canyons to regional tectonics and interaction of Paleogene Lower Wilcox high frequency sequences with the Yoakum Canyon

by Clarke Austin Clayton

In northern Gulf of Mexico, a clustering in a 100-150 km wide area of six Late Cretaceous-Paleogene age incisions up to 1000 m deep and 100 km long suggest a structural rather than eustatic control. The incisions counterintuitively align with the basinward trend of the San Marcos Uplift instead of forming in front of large sediment fairways (rivers) that formed depocenters of the Rio Grande and Houston embayments. The Sabine Arch and LaSalle Arch also uplift regions around the Gulf of Mexico Basin, which align with large slope incisions that indicate a possible main control of tectonism on canyon formation. This study proposes three new possible mechanisms, shelf edge bulge model, low uplift rate model (LUR), and high uplift rate model (HUR), for canyons formation in addition to the two conventional models of cutting during lowstand (Posamentier et al., 1991) and cutting during transgression (Galloway, 1991). In addition to the tectonic control of canyon formation, canyon evolution can be longer lived than previously described for some of the Wilcox Group large-scale incisions. By mapping 12 high frequency regressive-transgressive sequences within the Lower Wilcox in the San Marcos Arch region: (1) Sand thickening patterns towards the Yoakum Canyon margin (2) Mis-match of log signature correlation across the Yoakum Canyon (indicating the canyon acted as a sediment barrier in the study region) suggest that canyon was active for a longer period than previously described.With the Yoakum Canyon being active during Lower Wilcox time, the canyon(s) evolution would be in the scale of 4 to 5 million years rather than 1 million to 100,000 years. Over this time scale, the deep-water sediment was delivered into the submarine canyon (s) when lateral switching of the shelf-delta depocenters reached close to the head of the canyon during delta transits across the inner to outer shelf. The relationship of Wilcox Group incisions with tectonics and long-lived evolution of canyons provides insight into the large volume of clastic sediment and possible new mechanisms for sediment delivery to the deep water Gulf of Mexico.Advisors/Committee Members: Steel, R. J. (advisor), Olariu, Cornel (advisor).