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ABSTRACT: Timing of Source Rock Maturation in the Northern Gulf of Mexico Basin: Results from Thermal Modeling of a Regional Profile

NELSON, ERIC J., and PAUL WEIMER, University of Colorado, Boulder, CO; JULIA CALDARO-BAIRD, Texaco Inc., Denver, CO; and BARRY McBRIDE, HS Resources, Denver, CO

Maturation modeling along a 600 km long restored cross section in the northern Gulf of Mexico Basin allows estimation of the timing of source rock maturation. Forty 1-D thermal models, at a spacing of 15-25 km, were constructed along the series of restored cross sections. The cross section extends from the Mississippi-Louisiana border to south of the Sigsbee Escarpment. Source intervals modeled along the profile are of Eocene, Turonian, Tithonian, and Oxfordian-age; their areal extent and kerogen type were based on published reports.

In northern Louisiana, Turonian source rocks reached peak oil generation (0.9% R) at 31 Ma. In the Oligo-Miocene detachment province, Eocene source rocks reached peak oil generation at 14-12 Ma.

In the shelf and slope provinces, considerable variations exist in the maturation windows based on the presence of allochthonous salt, its rates of deformation, and its effect on heat flow. In the late Miocene-Pliocene province, Eocene source rocks reached the peak oil window at 14-5.5 Ma.

The tabular salt-minibasin province comprises southern Green Canyon (Tithonian source) and northern Walker Ridge (Oxfordian source). In southern Green Canyon, peak oil was reached at 65-10 Ma. In northern Walker Ridge, peak oil was reached at 9.5 Ma. In the abyssal plain, the source rocks have not yet reached the peak oil window or reached it in the last 0.5 Ma.



AAPG Search and Discovery Article #90908©2000 GCAGS, Houston, Texas