PALEOCENE PALEOENVIRONMENTAL AND PALEOCLIMATIC RECONSTRUCTION BASED ON PALYNOLOGICAL ANALYSIS OF THE ALO-1 WELL, SOUTHEASTERN NIGERIA

The sensitivity of organic walled microfossils (palynomorphs), such as pollen, spores, dinoflagellate cysts, and acritarchs to changes in sedimentary processes makes them useful proxies for inferring Phanerozoic biostratigraphy, paleoenvironments, paleoecology, and paleoclimates. Dinoflagellate cysts are especially abundant in the neritic environment and are the main focus of this palynological study of 33 samples from the Paleocene interval in the Alo-1 Well, northern Niger Delta Basin. The lower part of the studied interval (Danian-Selandian) is characterized by superabundance (>80%) of the mainly inner neritic Cordosphaeridium group (Cordosphaeridium spp., Ifecysta spp., Dammasadinium spp., and Lanternosphaeridium spp.), and >50% terrestrial palynomorphs. The decline of the Cordosphaeridium group (about 50% or less) and terrestrial palynomorphs (<50%) in the overlying interval suggests an upward deepening of the environment from the Danian to the Thanetian. The consistent abundance of thermophilic dinoflagellate cyst taxa throughout the studied interval indicates that warm climatic conditions prevailed during the Paleocene. The succession of the Cordosphaeridium group by an acme of Apectodinium spp. in the Thanetian confirms the warming event that characterized the Late Thanetian-Early Ypresian worldwide.