Adebayo Olufemi Ojo et al./ Elixir Geoscience 43 (2012) 6982-6986 6982 Introduction The Niger Delta Basin is the most prominent sedimentary basin on the continental margin of the Gulf of Guinea; it is also the most prolific in terms of oil and gas. This petroliferous nature has made it, for many years, the subject of continuous, consistent and extensive geologic investigations both for academic and economic purposes. Of recent, there has being a growing concern among the petroleum explorationists working in the basin that the oil exploration effort no longer yields expected results (Ojo 1 ) which has given rise to new challenges. One of such challenges is the need to revisit the geology of the basin. This requires the employment of various geological disciplines such as palynostratigraphy. Palynomorphs are ubiquitously present in sedimentary rocks of all ages from Archaean (ca. 3.8 billion years ago) to Recent, they are being used as sensitive indicators of the process of sedimentation, the direction of current, the source and age of sediments in many parts of the world (Sowunmi 2 ; Poumot 3 ; Eisawi and Schrank 4 ). Since less than ten percent of the work so far on microfossils in the basin are on palynological studies (Adebayo 5 ), hence, this work is to identify as much as possible the characteristic palynological assemblage of the sediments in the studied wells and use it to refine the biostratigraphic zones in the basin. Geological Setting of the Niger Delta Basin The basin is situated in the Gulf of Guinea, on the West African continental margin (Fig. 1). It extends throughout what Klett et al. 6 defined as the Niger Delta Province. The basin contains Upper Cretaceous to Recent marine to fluvial deposits overlying oceanic crust and fragments of the African continental crust (Doust and Omatsola 7 ; Kostenko et al. 8 ). The Delta began developing in the Eocene. From the Eocene to the present, the delta has prograded southwestward forming depobelts, each depobelt represent the most active portion of the delta at each stage of development (Doust and Omatsola 7 ). The sedimentary sequence in the Tertiary basin consists in ascending order of three diachronous formations, namely: Akata (marine beds), Agbada (transitional sand-shale beds) and Benin (continental sediments) formations (Short and Stauble 9 ). Fig. 1 Sedimentary Basins in Nigeria Showing the Niger Delta Basin and well location (Modified from Whiteman 10 ; Benkhelil 11 ). Materials and Method of Study Twenty five shaly samples taken at 60 ft interval from CHEV-1 well (3130-6031ft) in the offshore section of the western Niger Delta, Nigeria were subjected to palynological treatment. Standard maceration technique (Faegri and Inversen 12 , Wood et al. 13 ) was followed in the preparation of these samples. Samples were treated with HF and HCl to remove calcareous and siliceous materials respectively; heavy liquid separation using zinc chloride and hydrochloric acid solution (specific gravity 2.0) and finally acetolysis to dissolve cellulose for easy identification of palynomorphs. Minor modifications such as varying the percentage of hydrochloric acid (30-36%) used, staining of some residues and excluding acetolysis step for older samples with no cellulose. After treatment, samples were mounted on slides and studied under x40 and x100 objective using an Olympus CH30, camera-attached microscope. Photomicrographs of the most important palynomorphs were taken. Tele: E-mail addresses: adebayoolajide2003@yahoo.co.uk © 2012 Elixir All rights reserved Palynostratigraphy and paleoecology of chev-1 well, southwestern Niger delta basin, Nigeria Adebayo Olufemi Ojo and Olajide Femi Adebayo* Department of Geology, Ekiti State University, P. M. B. 5363, Ado-Ekiti, Nigeria. ABSTRACT Twenty five ditch cutting samples from southwest Niger Delta basin were analysed to determine the palynostratigraphic studies. The samples contained very rich and diverse palynomorphs dominated by pollen grains which consist of 12 species distributed among ten genera. Pollen preservation is good with concentration ranging from 1,640 to 34,900 grains/g. The stratigraphic ranges of Circulina parva, Monoporites annulatus, Psilatricolporites operculatus, Multiareolites formosus, Zonocostites ramonae, Podocarpus milanjianus, Echitricolporites spinosus, Retibrevitricolporites obodoensis, R. protrudens and Retitricolpites bendensis and some other marker species were used to demarcate nine palynozones in the study area. These palynomorphs are mainly made up of mangrove swamp floras which suggest the predominance of a high sea level and wet climatic condition in Miocene-Pliocene during the deposition of the studied sediments. © 2012 Elixir All rights reserved. ARTICLE INFO Article history: Received: 1 December 2011; Received in revised form: 6 February 2012; Accepted: 17 February 2012; Keywords Palynomorphs, Pollen, spores, Echinae, Niger Delta. Elixir Geoscience 43 (2012) 6982-6986 Geoseience Available online at www.elixirpublishers.com (Elixir International Journal)