Paleogene-Early Neogene Palynomorphs from the Eastern Equatorial Atlantic and Southeastern Florida, USA: Biostratigraphy and Paleoenvironmental Implication

The transition from greenhouse conditions (Paleocene-Eocene Thermal Maximum, PETM) to icehouse conditions (Early Oligocene) is not well documented in tropical-subtropical regions. One hundred and five samples from Ocean Drilling Program (ODP) Site 959 (Hole 959A and Hole 959D) in the Cote d'Ivoire-Ghana Transform Margin, Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria, and W-17001 in southeastern Florida were studied for their palynological contents. Dinoflagellate cysts were mainly utilized for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and Late Eocene-Early Miocene (ODP Hole 959A and W-17001). Palynofacies analysis and lithologic descriptions supplemented palynomorph data for paleoenvironmental reconstructions in ODP Hole 959A and W-17001. In ODP Hole 959D, five biozones were erected, a Late Paleocene hiatus event was identified, four new dinoflagellate cyst species were formally named, and an outer neritic paleoenvironment was inferred. The paleoenvironment was shallower (inner neritic) in the Alo-1 Well which yielded two new species and had four biozones. Five biozones were established for the Late Eocene-Early Miocene interval in ODP Hole 959A, proposed the Late Eocene as a new age assignment for lithologic subunit IIB, noted a hiatus event upsection, and observed new biostratigraphic ranges for two dinoflagellate cyst species. A deep paleoenvironment with relatively cold-water masses during the Early Oligocene and hyperstratified conditions was proposed. Two hiatus events and fluctuations between restricted marine and open marine paleoenvironments were inferred in the W-17001.