Stratigraphy of the Late Middle Eocene to Early Oligocene in the Bath Cliff Section, Barbados, West Indies

Abstract

Changes in fauna and flora across the Eocene Oligocene boundary are documented in an expanded section of indurated deep sea oozes and ash beds deposited close to the CCD [carbonate compensation depth] and now exposed at Bath Cliff, Barbados. A sedimentation rate of 27 m/million yr for the Late Eocene is calculated. The spread of events through time does not suggest any catastrophe at the boundary. The last occurrence of disc-shaped discosaters (CP 15/CP 16 Zone boundary) occurs before the last occurrence of Hantkenina, which is taken to represent the epoch boundary. The last occurrence of Turborotalia cerroazulensis s.l. occurs slightly before the boundary; the Cryptoprora ornata/Theocyrtis tuberosa radiolarian Zone boundary occurs slightly after it. The Thyrsocyrtis bromia radiolarian Zone of the Late Eocene has been replaced by 3 new zones, from top to bottom: C. ornata Zone, Calocyclas bandyca Zone, and "Carpocanistrum" azyx Zone. A microtektite horizon occurs in the Cryptoprora ornata Zone slightly < 1 million yr before the epoch boundary. In the basal Oligocene a sudden enrichment of 18O in Oridorsalis umbonatus suggests a drop in bottom water temperature of 5.degree.-6.degree. C.