Geophysics and Geodynamics Research at Colorado State University

Research in Progress

Seismic, Gravity, and Well Constraints on the Structure of the U.S. Gulf of Mexico Coastal Plain and Continental Margin in Mississippi

(Harry and Londono)

Seismic reflection, seismic refraction, well, and gravity data have been used to constrain the subsurface geology along a crustal-scale transect trending from western Tennessee through eastern Mississippi and into the central Gulf of Mexico. One such profile, shown below, illustrates the major results. The top figure shows the gravity data and modeled gravity field. The central figures shows at a 5:1 scale the geological structure with well control indicated at the top. Seismic reflection (solid black line at the top) and seismic refraction control (dashed lines on the cross section) are also shown. The bottom figure shows the cross section at a 1:1 scale. The subsurface geology is characterized by a suture zone formed during the Late Paleozoic collision of an alloucthonous terrane with the southern Laurentian margin. The abrupt thinning of the continental crust on the ancient Laurentian margin (located at ca. 500 km) is similar to modern transform continental margins, and supports prior arguments that this part of the Laurentian margin was a transform margin. The Ouachita orogenic belt is underlain by subducted oceanic crust emplaced in a south verging subduction zone when the allocthonous terrane collided with North America. The Ouachita fold and thrust belt is a thin-skinned feature overlaying this suture zone, with sediments in the associated Black Warrior Foreland Basin underlaying the leading edge of the fold and thrust belt. Mesozoic continental extension created the slightly extended Mississippi Salt Basin, but most Mesozoic extension was focused south of the Wiggins Arch, resulting in formation of the deep Gulf Coast Sedimentary Basin. These results are part of ongoing studies into the petroleum potential of the Black Warrior Basin, Mississippi Salt Basin, and the Gulf Coast Basin (click on image for larger view).

D.L. Harry, and J. Londono, Structure and evolution of the central Gulf of Mexico continental margin and coastal plain, southeast United States, GSA Bulletin, 116, 188-199, 2004.

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