Abstract
The palynofacies study carried out on offshore ditch cuttings from AJ-X well in Dahomey basin revealed different types of palynodebris. To assess the pattern of distribution of the palynofacies types, their abundances were submitted to Cluster analysis and Principal component analysis. The PCA diagram consists of four curves, PC1, PC2, PC3 and PC4 with a cumulative variance of 45.8% showing fluctuations in PC curves supporting the response of the palynodebris to changing environments. The cluster for the well revealed two super clusters based on the abundance and composition of the kerogen groups. These are informally designated as: super cluster X, which is subdivided into X1, X2 and X3, and super cluster Y, subdivided into Y1 and Y2. X1 is composed mostly of phytoclasts and a moderate abundance of the AOM group (Phy/AOM); X2 of high abundances of phytoclasts combined with moderate to high abundances of palynomorphs (Phy/Pal); and X3 is composed of very high abundances of phytoclasts (Phy). The high abundances of the AOM group occur in super cluster Y. Y1 is characterized by very high abundances of the AOM group. In Y2 this group occurs with phytoclasts and, in particular with the palynomorph group (AOM/Pal). The major break that occurred between clusters X and Y is strongly related to the abundance of the phytoclasts group. The size, shape and texture of all the components were integrated with sedimentological features and palynomorphs to recognize distal suboxic-anoxic shallow neritic shelf environment.
Highlights
Combaz [1] introduced the concept of palynofacies which refers to suites of palynodebris
Conclusions yy The Principal component and cluster analysis based on the abundance and composition of all palynodebris in AJ-X well revealed four super clusters
Yy Based on the distribution of palynofacies associations that defined five palynofacies units in well, a continuous terrestrial influx is indicated throughout the succession by moderate to very high abundances of phytoclasts
Summary
Combaz [1] introduced the concept of palynofacies which refers to suites of palynodebris. Batten [2,3] applied the concept towards understanding provenance of sediments and the association of palynodebris with hydrocarbon. The eastern Dahomey basin or the Nigeria sector contains extensive wedge of Cretaceous to Recent sediments, up to 3000 m which thicken towards the offshore. Various workers have studied the various sediments of the eastern Dahomey basin and came forward with documentations concerning its age, lithology, structure, mineralogy etc. In coastal and offshore areas of the basin, sediments in excess of 3000 m thick ranging from Albian to late Miocene have been recorded from exploration drilling [15,16,17]. Sediments age range generally from upper cretaceous to Miocene. Upper Albian sediments have been recognized based on palynological studies [15]
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call