A new Late Miocene to Pleistocene palynomorph zonation for the western offshore Niger Delta

摘要

Existing biozonation schemes for the Niger Delta are mainly qualitative with zonal intervals too large to record subtle events. This has made it necessary to look for additional palynological events to enable recognition of shorter, more refined interval zones to improve stratigraphical definition. Hitherto unrecognised occurrence trends of palynomorphs were discovered and used to construct a new zonation scheme that can be applied in the offshore delta area. Late Miocene to Early Pleistocene sediments have been divided into five principal assemblage zones: FF1, Anthoceros abundance zone; FF2, Elaeis guineensis-Echiperiporites icacinoides zone; FF3, Lycopodium-Retibrevitricolporites obodoensis/protrudens zone; FF4, Cyperaceae abundance zone; and FF5, Echitriletes pliocenicus-Podocarpus milanjianus zone. The zones are further subdivided into 16 sub-zones based on quantitative events with some having finer subdivisions into (a) and (b). Examples of the zonations applied to three exploration wells from the western delta region are provided.