Early eocene (ypresian) benthic foraminiferal assemblages, the Rio Sambre section, Jamaica

Access to thesis permanently restricted to Ball State community only.This study focused on smaller benthic foraminifera in the Ypresian aged Rio Sambre section from the Wagwater Trough in Jamaica. Deposition of the Rio Sambre Section occurred in the Middle Bathyal Zone. The section was originally thought to cross the Ypresian-Lutetian boundary, however, an updated biostratigraphic framework from this study and recent publication reveals the entire Rio Sambre Section to be entirely Ypresian. The Rio Sambre Section contains predominantly deep-water calcareous benthic foraminifera with sporadic influences of shallow water taxa and arenaceous assemblages. Five distinct assemblages were observed in the Rio Sambre Section. The deep-water assemblages are mostly comprised of epifaunal morphotypes, which live at or near the sediment water interface. Several increases of infaunal morphotypes which live below the sediment water interface were also observed. Common Fluctuations between infaunal and epifaunal morphotypes were observed throughout the studied section. These are likely the result of episodic turbidic input of organic matter. The turbidic events often led to an increase of shallow water taxa, such as Discorbis Sp. 1, in the deeper water assemblages. An inverse relationship was formed between Discorbis Sp. 1 and an infaunal uniserial calcareous fauna. The proposed cause of the relationship is that the Discorbis sp. 1 were transported from shallow water to deeper water by turbidic events. These turbidic events in turn transported large amounts of organic matter into the deeper water. This created an anoxic environment and the uniserial calcareous foraminifera which can survive in low oxygen environments were able to thrive until the organic matter was depleted. This was followed by a normal deep water benthic foraminiferal assemblage as organic matter stabilized.Thesis (M.S.