From Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
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American Association of Petroleum Geologists Annual Meeting, Dallas, April 18-21, 2004

Late Cenozoic Intrabasinal Deformation in Offshore Laguna Madre-Tuxpan Continental Ahelf and Related Deepwater Mexican Ridges Fold Belt

Timothy F Wawrzyniec, John Swenson, William Ambrose, Khaled Fouad, Mario Aranda, Eduardo Macías Zamora, and Luis A. Sanchez-Barreda

Abstract:

The western Gulf of Mexico (GOM) is affected by a coupled system of shelf-wide extension within the Laguna Madre-Tuxpan continental shelf and the deepwater fold belt known as the Mexican Ridges. Distributed extensional faulting initiated in the early Miocene and, by the Pliocene, most of the shelf growth faulting was localized to a single listric growth fault (the Faja de Oro fault). Offset along this structure over the last 4 to 5 m.y.s appears to pin the shelf/slope transition to within 2 to 15 km of the shallow fault tip. Previous investigations linked accommodation and the related detachment surface to a mobile substrate. More recent publications regarding the Mexican Ridges attribute extensional accommodation and formation of the foldbelt to load-driven, gravitational sliding. A third hypothesis is that extension along the shelf is driven by gravitational loading within the Burgos Basin rather than by a dynamic equilibrium between shelf sedimentation and slip rates. The first hypothesis is ruled out by the lack of any regional diapir complexes within this part of the western GOM. Variations observed in depositional styles and a linear variation in finite slip along the Faja de Oro fault suggest that a dynamic equilibrium may not exist along the entire length of the fault. Rather, deformation may be in-part externally forced. We combine careful seismic interpretation and reconstruction with stratigraphic modeling to investigate the style of accommodation in the western GOM and thereby quantify the relative role of internal depositional loading and extrinsic tectonic forcing.