Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
2003 GCAGS-GSCSEPM Annual Convention, Baton Rouge, Louisiana, October 2224, 2003
Neogene Valley-Fill, Slope, and Submarine-Canyon Systems on a Narrow, Bypassed Shelf, Offshore Laguna Madre-Tuxpan Continental Shelf, México
William Ambrose, K. Fouad, D. Jennette, L. F. Brown, T. Wawrzyniec, S. Sakurai, E. Guevara, M. Aranda, J. Alvarado, U. Hernandez, E. Macias, D. Velez, F. Sanchez, and J. C. Flores
The Bureau of Economic Geology and Pemex Exploración y Producción conducted a joint study of Neogene sequences and depositional systems in the Laguna Madre-Tuxpan continental shelf between the Veracruz and Burgos Basins. Using a data set containing six 3-D surveys, more than 5,000 linear kilometers of 2-D seismic lines, and more than 60 wells, this study documents a major system of sediment bypass on a narrow (10- to 15-km) Miocene shelf, with hundreds of meters of section dissected by valley-fill and submarine canyon systems genetically linked to sandy basin-floor-fan systems eastward. Incised-valley-fill deposits, inferred from downcutting, lenticular seismic facies on the shelf, are narrow (less than 2 km across), and many are shale filled. In contrast, downdip canyon systems linked to these valley fills are as much as 6 km across and show a variety of internal architectures. Although some canyons are shale filled, many in the southern part of the Tuxpan area are filled with offlapping, progradational delta-front deposits of highstand origin. These canyon fills have clinoform geometries, in contrast to basal canyon-fill deposits that onlap onto canyon margins. The Oligocene Hackberry trend of southeastern Texas and southwestern Louisiana is an analog for middle Pliocene shale-filled submarine canyons east of the Tuxpan Platform. The Hackberry trend is associated with sandy, productive toe-of-slope fans that were fed from updip canyon systems notched into the shelf. Isochron maps of the middle Pliocene east of the Tuxpan Platform suggest the presence of thick, potentially sandy deposits having a similar depositional origin.