Paleoclimatic Reconstruction of Middle to Late Miocene Strata Evidenced from Palynological Study of Ida-4 Well, Eastern Niger Delta, Nigeria

Abstract

This study presents the results of a paleoclimatic study on ditch cutting samples within the interval of 2179 – 3523 m from Ida-4 well, Eastern Niger Delta Basin. The aim is to identify the different species of palynomorphs present in the samples for the reconstruction/recognition of climatic changes during the middle to late Miocene epoch. The acid technique of sample preparation for palynomorphs recovery was used. Diverse and moderately rich pollen and spores were recovered. The biostratigraphic age control of the studied interval was identified based on the first and last downhole occurrences of Multiareolites formosus, Peregrinipollis nigericus and Crassoretitriletes vanraadshoveni, Verrutricolporites rotundiporus, Racemonocolpites hians and Magnastriatites howardi which are diagnostic of middle to late Miocene. The method of grouping the recovered palynomorphs into palyno-ecological groups was adopted for the paleoclimatic reconstruction. Intervals of temperate, wet and dry climatic zones were delineated from recurrent/fluctuation of the recovered palynomorphs sequences (palyno-ecological groups) at the different depth intervals. The delineated climatic zones are indications of vegetation, climate and sea level change during the Miocene.