Print this pageThe Ups and Downs of the Sabine Uplift and
the Northern Gulf of Mexico Basin: Jurassic Basement Blocks,
Cretaceous Thermal Uplifts, and Cenozoic Flexure
Thomas E. Ewing
Yegua Energy Associates LLC, 19240 Redland Rd., Ste. 200, San Antonio, Texas 78259
ABSTRACT
The eastern part of the northern Gulf of Mexico Basin is characterized by a series of high-standing basement blocks that correlate to thick, less extended continental crust, and are separated by deep basins with thick salt accumulations that correlate to thin, more extended continental crust. Post-rift depositional systems are strongly affected by these basement blocks, which are areas of lesser subsidence and boundaries to basins with active salt movement.
The Sabine Uplift is the largest, best known, and probably most complex of these highs. Geophysical data confirm it as a block of thick crust. The few deep wells have found late Paleozoic sediments associated with Mississippian volcanic rocks. The originally highest known parts of the complex are at the south (“Sabine Island”) where Smackover is absent and Haynesville and/or Bossier shale rests on Paleozoic rocks. Other areas have a thin to normal succession of Louann Salt, Smackover Limestone, and Haynesville limestone and shale, with an internally complex pattern suggesting a poorly-resolved internal structure to the original uplift. Thick Haynesville organic shales occur on the eastern and northeastern flanks of the overall complex. Later Bossier / Cotton Valley sandstone deposition shows little effect of the uplift.
The Late Cretaceous history of the northern Gulf of Mexico is complex, including igneous activity and a broad array of overlapping domal uplifts. Significant regional unconformities occur below the Tuscaloosa (Cenomanian) in north Louisiana and southern Arkansas (the Southern Arkansas Uplift), below the Austin (Turonian-Coniacian) in east Texas (the “Rusk Uplift”), and later in the Cretaceous elsewhere (the Monroe and Jackson uplifts, associated with 65-80 Ma volcanism). The Southern Arkansas Uplift, over 350 km (210 mi) wide, removed up to 3 km (10,000 ft) of section and affected a wide area. It was centered north of the Cretaceous subcrop, where extensive and voluminous 89-106 Ma igneous activity is known. The overlapping Rusk Uplift (175 m [575 ft] of erosion) lacks known igneous activity, but may be associated with intrabasement mafic intrusions. Three endmembers of this family of uplifts are inferred to represent (1) crustal heating due to igneous intrusion, (2) subcrustal heating due to mantle upwelling, and (3) flexural uplift due to development of the Mexican Laramide fold and thrust belt and associated foredeep. The Rusk Uplift is affected by both subcrustal heating and distant flexural effects.
Cenozoic activity includes post-Wilcox (Middle Eocene?) arching (possibly driven by Laramide flexure), and post-Eocene flexural
uplift of the northern and central parts of the Sabine area, caused by post-Eocene sediment loading to the south and southeast.
Ewing, T. E., 2009, The ups and downs of the Sabine Uplift and the northern Gulf of Mexico Basin: Jurassic basement blocks,
Cretaceous thermal uplifts, and Cenozoic flexure: Gulf Coast Association of Geological Societies Transactions, v. 59, p. 253-269.
AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana