Seismic Stratigraphy of Veracruz Tongue, Deep Southwestern Gulf of Mexico

Abstract

The Veracruz Tongue is a region of continental slope and rise sediments bounded bathymetrically by the Mexican Ridges fold belt to the west and the Campeche Knolls salt province to the east. Study of two multichannel seismic lines and single-fold sparker data enables five post-early Miocene seismic stratigraphic sequences to be distinguished in the tongue. Sedimentary processes responsible for deposition of each sequence are inferred on the basis of external geometry, internal reflection configuration, and, where possible, core data. The five sequences are each interpreted to consist of turbidites grading laterally into hemipelagites. These primary deposits may be modified later by downslope creep or sliding and slumping. Because bathymetry is a major control on location of turbidity-current flows, slides, and slumps, the depositional history of the Veracruz Tongue provides indirect evidence of tectonic evolution of the Mexican Ridges fold belt and the Campeche Knolls salt province. Salt domes first formed a barrier to turbidity-current flow from the east at the close of the middle Miocene. The Mexican Ridges fold belt evolved gradually until it formed a complete barrier to turbidity-current flow from the west at the close of the Pliocene. As a result of shift in direction of turbidity-current flow through time, potentially sand-prone Miocene turbidites are overlain by hemipelagic clays and clayey oozes--a situation favorable to hydrocarbon entrapment.