BENTHIC FORAMINIFERA FROM THE CHAPELTON FORMATION (EOCENE; LUTETIAN) AT THE SEVEN RIVERS SITE, WEST-CENTRAL JAMAICA

The Seven Rivers site in west-central Jamaica (St. James Parish) is well known for its assemblages of aquatic vertebrates of early middle Eocene (Lutetian) in age. The lower 3 meters of the Guys Hill Member of the Chapelton Formation at Seven Rivers contains abundant marine fossils including mollusks, echinoderms, ostracods, and foraminifera. Benthic foraminifera are of particular interest as they may provide information on paleoecology and relative bathymetry through the section.

The benthic foraminiferal fauna from the lower 0.5 m of the section is characterized by an assemblage of Quinqueloculina, Anomalinoides, Lenticulina, Alabamina, and Cibicidoides. Several planktonic foraminfera have been collected from this interval including Acarinina bullbrooki, Acarinina pentacamerata, and Dentoglobigerina yeguaensis. The middle 1.5 meters of the Seven Rivers section contains a benthic foraminiferal assemblage dominated by species of Quinqueloculina, Spiroloculina, Massilina and Eponides. The upper 1 m of the section is characterized by a low diversity assemblage domnated by species of Textularia and Gaudryina. The lower 2 meters of the section also contains isolated specimens of macroforaminifera including Fabularia vaughani.

The benthic foraminiferal assemblages record a transition in paleoenvironment from shallow, open marine conditions through marginal marine conditions. The planktonic foraminifera along with the macroforaminifera indicate the age of the Seven Rivers section is early Lutetian in age and can be no older than planktonic foraminiferal zone E8 and no younger than planktonic foraminiferal zone E10. This is consistent, although more limiting, than previous correlations based on mollusks and fossil mammals.