Dinoflagellate cyst assemblages, biostratigraphy and paleoenvironment of a Paleocene-Early Eocene sedimentary succession in the northern Niger Delta Basin: Comparison with low, mid and high latitude regions

We use the last occurrence and/or last abundance events of dinoflagellate cysts to identify four biostratigraphic zones (zone E to zone H) in the Alo-1 Well. Lithostratigraphic and biostratigraphic analyses suggest a late Selandian age for the contact between the Imo and Nsukka formations. Abundant thermophilic taxa that include the Cordosphaeridium group and Apectodinuim dominate the assemblage recovered in the depositional succession. The late Selandian to early Thanetian sediments are dominated by the Cordosphaeridium group, and are succeeded by abundant to superabundant marker species of Apectodinium in the late Thanetian to Ypresian. The superabundance of Apectodinium is significant because it is indicative of the global intense climatic warming that characterized the late Thanetian to early Ypresian. The Alo-1 Well dinoflagellate cyst data also suggest deposition under proximal, inner neritic conditions that preserved an assemblage dominated by species of Cordosphaeridium, Damassadinium, Ifecysta and Polysphaeridium.