Benthic Foraminiferal Zonation on Northwestern Gulf of Mexico Slope: A Close Look

Richard A. Denne, Barun K. Sen Gupta

Dominant benthic foraminifera in 60 core tops from the eastern Texas and western Louisiana continental slope, within a depth range of about 100-1,000 m, show significant abundance variations. Overall, Cassidulina subglobosa, C. neocarinata, and Uvigerina peregrina are abundant at all depths within the studied range. Bolivina subaenariensis mexicana, Uvigerina parvula, U. bellula, and Bulimina spicata are abundant above 300 m and rare below 400 m. Gavelinopsis praegeri, Eponides turgidus, Bolivina albatrossi, and B. ordinaria are abundant below 200 m. Bulimina aculeata, B. alazanensis, and Epistominella exigua are common below 500 m and rare above 400 m. More specifically, Bulimina aculeata and B. alazanensis first occur below 200 m, become common below 400-500 m, and atta n abundance below 600-700 m. Several other species, whose upper depth limits are between 100 and 1,000 m, are also rare in the first few hundred meters of their depth ranges. Major shifts in faunal dominance occur in water mass-transition zones at 200-400 m and 800-900 m.

AAPG Search and Discovery Article #91036©1988 GCAGS and SEPM Gulf Coast Section Meeting; New Orleans, Louisiana, 19-21 October 1988.