PALEOENVIRONMENTAL AND PALEOCLIMATIC RECONSTRUCTION OF OM-4 AND OM-A WELLS, NIGER DELTA, NIGERIA

Abstract

Palynological studies have been carried out on 100 ditch cuttings samples penetrated by OM-4 wells in the Niger Delta, Nigeria, with the aim of reconstructing the paleoenvironment and paleoclimate of the interval studied which ranged from 8200-11400ft each in both wells. The palynomorphs yielded 51 and 44 species in OM-4 and OM-A wellsrespectively. The succession studied yielded rich terrestrial components of the palynomorphs assemblage which gave zero to low PMI values in both wells, suggesting a paralic environment. Also, the abundance of mangrove swamp species such as Zonocostites ramonae, Acrostichum aureum, Botryococcus braunii and Psilatricolporites crassus in both wells (which are brackish water indicators) denotes an environment of deposition with higher terrestrial influences, indicating a paralic environment of deposition. The palynomorph distribution was also used to interpret the depositional climatic conditions and on the basis of changes in the vegetation shown in the nature of distribution of the paleoclimatic zones were established. Four zones in OM-4 well and five zones in OM-A well. These zones showed a variation between dry and wet climates.