Patricia E. Ganey-Curry

Cenozoic depositional history of the Gulf of Mexico basin

A Geographic Information System (GIS) database incorporating information from 241 publications, theses, and dissertations; well logs and paleontologic reports; and interpreted University of Texas Institute for Geophysics (UTIG) deep-basin seismic lines was used to map and interpret 18 basinwide genetic stratigraphic sequences that form the Gulf of Mexico basin Cenozoic fill. Eight principal extrabasinal fluvial axes provided the bulk of the sediment infill in the basin. First-order temporal and spatial use of these axes reflects four continent-scale phases of crustal uplift. Abundant sediment supply has prograded the northern and northwestern basin margin 150 to 180 mi (240 to 290 km) from its inherited Cretaceous position. Margin outbuilding has been locally and briefly interrupted by hypersubsidence due to salt withdrawal and mass wasting. Three depositional systems tracts characterize Cenozoic genetic sequences: (1) fluvial --> delta --> delta-fed apron, (2) coastal plain --> shore zone --> shelf --> shelf-fed apron, and (3) delta flank --> submarine fan. One or more examples of the fluvial --> delta --> delta-fed apron systems tract occur in each of the major genetic sequences. Immense volumes of sand have bypassed the shelf margin to be deposited in slope and base-of-slope systems, primarily within fluvial --> delta --> delta-fed apron system tracts, during all major Paleogene and Neogene depositional episodes. Deposition and preservation of volumetrically significant coastal plain --> shore zone --> shelf --> shelf-fed apron tracts is typical of Paleogene through Miocene depositional episodes only. Fan system origin was commonly associated with major continental margin failures, but large submarine canyons occur mainly in Pleistocene sequences. Thick, potential reservoir sand bodies occur in offlapping delta-fed slope and subjacent basin floor aprons, in autochthonous slope aprons and related infills of slide scars and canyon cuts, and in submarine fans.

History of Cenozoic North American drainage basin evolution, sediment yield, and accumulation in the Gulf of Mexico basin

The Cenozoic fill of the Gulf of Mexico basin contains a continuous record of sediment supply from the North American continental interior for the past 65 million years. Regional mapping of unit thickness and paleogeography for 18 depositional episodes defines patterns of shifting entry points of continental fluvial systems and quantifies the total volume of sediment supplied during each episode. Eight fluvio-deltaic axes are present: the Rio Bravo, Rio Grande, Guadalupe, Colorado, Houston-Brazos, Red, Mississippi, and Tennessee axes. Sediment volume was calculated from digitized hand-contoured unit thickness maps using a geographic information system (GIS) algorithm to sum volumes within polygons bounding interpreted North American river contribution. General age-dependent compaction factors were used to convert calculated volume to total grain volume. Values for rate of supply range from >150 km to <10 km3/Ma. Paleogeographic maps for eleven Cenozoic time intervals display the evolving matrix of elevated source areas, intracontinental sediment repositories, known and inferred drainage elements, and depositional fluvial/deltaic depocenters along the northern Gulf of Mexico basin margin. Patterns of sediment supply in time and space record the complex interplay of intracontinental tectonism, climate change, and drainage basin evolution. Five tectono-climatic eras are differentiated: Paleocene late Laramide era; early to middle Eocene terminal Laramide era; middle Cenozoic (Late Eocene–Early Miocene) dry, volcanogenic era; middle Neogene (Middle–Late Miocene) arid, extensional era; and late Neogene (Plio–Pleistocene) monsoonal, epeirogenic uplift era. Through most of the Cenozoic, three to four independent continental-scale drainage basins have supplied sediment to the Gulf of Mexico.

Gulf of Mexico Basin Depositional Synthesis: Neogene Sequences, Depositional Systems, and Paleogeographic Evolution

ABSTRACT An industry-sponsored synthesis of the Cenozoic depositional history of the Gulf of Mexico basin has integrated well data from the onshore, shelf and upper slope areas with Fengs 1995 seismic stratigraphic interpretation of the deep basin. The first phase of the project identified 10 Neogene genetic sequences that record major depositional episodes of the Gulf basin. For each sequence, digitally recorded data include thickness, lithofacies, depositional systems, stratigraphic architecture, local depocenters and paleo-geographic features such as paleo-shelf edge positions and submarine canyons. These data are stored in GIS format (ARC/INFOTM). Results of this synthesis are summarized in a series of interpretative maps showing the depositional system paleogeography for each of 10 sequences throughout the Gulf basin: Lower Miocene 1 (24-18.2 Ma); Lower Miocene 2 (18.2-16 Ma); Middle Miocene (16-12.8 Ma); Upper Miocene (12.8-6.2 Ma); Miocene-Pliocene (Bul. 1) (6.2-4.9 Ma); Pliocene (Glob. alt.) (4.9-3.1 Ma); Pliocene (Lent. 1) (3.1-2.3 Ma); Pliocene (Ang. B) (2.3-1.6 Ma); Pleistocene (Trim. A) (1.6-.55 Ma); and Pleistocene (Sang.) (.55-.27 Ma). The maps are supplemented by a series of regional reference margin well and deep basin seismic cross sections.

Gulf Basin Depositional Synthesis (GBDS) Phase I Project Atlas

The Gulf of Mexico Basin Depositional Synthesis (GBDS) is a comprehensive program of interpretation and description of the Cenozoic depositional history of the Gulf of Mexico basin that integrates well data from the onshore, shelf and upper slope areas and UTIG seismic stratigraphic interpretation of the deep basin. Contact gbds@ig.utexas.edu for more information.