NIGER DELTA PHYTOECOLOGICAL GROUPS DATA FOR THE NEOGENE-EARLIEST PLEISTOCENE
Description
The relationship between vegetation and climate informed the use of paleovegetational changes to infer paleoclimatic changes. Palynomorphs recovered from three oil wells from the offshore western Niger Delta were categorized into phytoecological groups to achieve this. Standard sedimentology and foraminiferal biostratigraphy integrated with marker palynomorphs were also applied to constrain the age. In the latest Miocene (5.8-5.5 Ma), climatic conditions were mainly wet until between 5.5 and 5.0Ma when extreme dry conditions prevailed. The early Pliocene (5.0 - >3.4 Ma) was generally wet while the late Pliocene (<3.0 - 2.7 Ma) was extremely dry with wet condition re-occurring at the latest Pliocene/earliest Pleistocene boundary at a lower magnitude than the early Pliocene wetness. This is inferred from the bloom of open vegetation Acanthaceae undifferentiated, Polygala sp. and Asystacia gangetica along with montane Podocarpus milanjianus since 2.4 Ma through 2.0 Ma and younger. The Acanthaceae bloom recorded the evolution of A. gangetica in the latest Pliocene/earliest Pleistocene around 2.0 Ma in the Niger delta. The upper Early Pliocene regional wet event is associated with distinct peaks of riverine forest, freshwater swamp and mangrove pollen. Results here further support earlier findings from other parts of West Africa with respect to paleoclimatic changes of the late Neogene/earliest Quaternary. Equivalent qualitative palynostratigraphic events were recognized within the zones for age determination and the biostratigraphic correlation significance of the zones was stressed.