--> Abstract: Seismic Stratigraphic Identification of Eustatic Cycles in Late Triassic, Jurassic, and Early Cretaceous Rocks--Gulf of Mexico and West Africa, by R. G. Todd, R. M. Mitchum; #90978 (1975).
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Abstract: Seismic Stratigraphic Identification of Eustatic Cycles in Late Triassic, Jurassic, and Early Cretaceous Rocks--Gulf of Mexico and West Previous HitAfricaNext Hit

R. G. Todd, R. M. Mitchum

Seismic stratigraphic techniques permit identification of Late Triassic, Jurassic, and Early Cretaceous eustatically controlled sequences in strata from the North American Gulf Coast and West Previous HitAfricaNext Hit. Eight distinct sequences are remarkably persistent from the Florida panhandle around the perimeter of the Gulf Coast into northern Mexico, a distance of over 1,500 mi. Their identification requires the integration of seismic data with lithologic, environmental-facies, biostratigraphic, radiometric, and well-log information. A comparison with strata of comparable age in offshore West Previous HitAfricaNext Hit indicates at least six coeval sequences are recognized there. The sequences in North America and Previous HitAfricaTop are interpreted to be eustatically controlled because they occupy the same time-strat graphic positions and display similar coastal onlap patterns to those previously recognized by us elsewhere in the world.

Gulf Coast eustatic cycles and the formations occurring within them are: (1) Late Triassic-Early Jurassic (Rhaetian-Hettangian)--Eagle Mills Formation; (2) Early Jurassic (Sinemurian through Toarcian)--known only from southern Mexico and not identified in the study area; (3) Middle Jurassic (Bajocian-Bathonian)--Werner Anhydrite-Louann Salt interval; (4) early Late Jurassic (Callovian)--Norphlet Formation; (5) Late Jurassic (Oxfordian-early Kimmeridgian)--Smackover Limestone-Buckner anhydrite section; (6) Late Jurassic (late Kimmeridgian)--Haynesville Formation; (7) Late Jurassic-Early Cretaceous (Tithonian-Berriasian)--most of the Cotton Valley Group; and (8) Early Cretaceous (Valanginian)--a restricted wedge seen only in a basinward position.

West African eustatic cycles are (1) Late Triassic-Early Jurassic; (2) Early Jurassic; (3) Middle Jurassic; (4) early Late Jurassic (Oxfordian-Kimmeridgian); (5) Late Jurassic-Early Cretaceous (Tithonian-Berriasian); and (6) Early Cretaceous (Valanginian). Further refinement may show additional sequences in Middle Jurassic and Late Jurassic intervals.

AAPG Search and Discovery Article #90978©1975 GCAGS-GC Section SEPM Annual Meeting, Jackson, Mississippi