Major oxides and trace elements analysis was carried out on ditch cutting samples of FE-1 well, Onshore, Niger Delta Basin, to define their oxygen condition, paleo-climatic conditions, provenance, tectonic setting, sandstone classification and maturity of the sediments. Sedimentological analysis revealed five main lithofacies comprising of sandstone, shaly sand, mudstone, sandy clay and sandy shale. Geochemical results indicates that the average value of silica (87.1 wt. %) is far higher than the average values of the rest oxides which shows the duration and intensity of weathering and destruction of other minerals during transportation. Bivariate plot of La/Sc versus Th/Co, Zr versus TiO2, and trace elemental ratios of Th/Sc, Th/Co, Th/Cr, Cr/Th, La/Sc establishes that the source of the sediment are from felsic rock. Different chemical classification schemes characterized the sediments as quartzarenite, lithic arenites and Fe-rich sand. The plot of Log (K2O/Na2O) versus Log (SiO2/Al2O3) and K2O/Na2O versus SiO2 all plotted mainly in the passive margin zone. The low average value of uranium content, trace elemental ratios of U/Th, Ni/Co, Cu/Zn, V/Cr and binary plot of Ni/Co versus V/Cr indicated an oxic environment of deposition. However, the binary plot of Ni/Co versus V/ (V+Ni) indicates oxic to anoxic condition during deposition of the mixed marine and terrigenous source input sediment. Binary plot of SiO2 versus (Al2O3+Na2O+K2O) designates deposition mainly in humid/semi-humid climatic condition. The samples studied have a much higher SiO2/Al2O3 ratio with low Fe2O3/K2O ratio, thus, they are mineralogically mature. The Al2O3/(CaO+MgO+Na2O+K2O) ratio inferred that there are stable mobile oxides in the samples. Keywords: Major oxides, lithic arenites, provenance, tectonic setting.

: Biostratigraphic study of Well DX has yielded Cretaceous miospores and dinoflagellates cysts which heightened the recognition of sequence boundaries (SB), Maximum Flooding Surfaces (MFS) and associated Systems Tracts. Five maximum flooding surfaces between 95.6 Ma and 89.0 Ma, four sequence boundaries between 96.4 Ma and 93.0 Ma and threedepositional sequences were identified with varying average thicknesses of sediments interpreted from the gamma ray log and biostratigraphic data. The threedepositional sequences interpreted are -depositional sequence I (96.4 Ma - 95.4 Ma) (8240 ft. - 8120 ft.), depositional sequence II (95.4 Ma - 94.0 Ma) (8120 ft. - 7850 ft.) and depositionalsequence III (94.0 Ma - 93.0 Ma) (7850 ft. - 7550 ft.). All the depositional sequences fall within the third order cycle. The age of the well was attempted based on the presence of some selected marker fossils - Ephedripites spp., Classopollis spp., Spiniferites spp., Cyclonephelium distinctum, Cyclonephelium vannophorum, Subtilisphaera spp., Eucomiidites spp., Triorites africaensis, Odontochitina costata and Droseridites senonicus recovered from the studied intervals and was dated Albian - Santonian. The Sequence stratigraphic interpretations are useful in further deepening the knowledge of thesubsurface geology of the studiedwell in Gongola Sub Basin, Upper Benue Trough of Nigeria.Keywords: Sequence Boundary, Maximum Flooding Surface, System tracts, Depositional sequence

The area of study is a portion of the Greater Ughelli Depobelt in Niger Delta Basin. The main aim of the paper is to interpret the sequence  stratigraphy of FX-1 and FX-2 wells by employing data sets from biostratigraphic data and well logs. Standard laboratory techniques were used for  data treatment while computer software such as Petrel and StrataBugs were used for data simulation, processing, integration and interpretation. Sedimentology, interpreted gamma ray and resistivity well logs integrated with biostratigraphic data were utilized to define the candidate maximum flooding surfaces and sequence boundaries. The wells have the following distributions of sequences: FX-1 well have five depositional sequences with eight candidate maximum flooding surfaces at depths 10011 ft., 9509 ft., 9437 ft., 6362 ft., 5752 ft., 5507 ft., 5161 ft. and 4816 ft. dated 34.0 Ma, 33.0 Ma, 31.3 Ma, 28.1 Ma, 26.2 Ma, 24.3 Ma, 23.2 Ma and 22.0 Ma and seven candidate sequence boundaries at 9616 ft., 6656 ft., 6116 ft., 5639 ft., 5424 ft., 4859 ft. and 4581 ft. dated 33.3 Ma, 29.3 Ma, 27.3 Ma, 24.9 Ma, 23.7 Ma, 22.2 Ma and 21.8 Ma, respectively. FX-2 well have four depositional sequences, five candidate MFSs were identified at 7764 ft., 7196 ft., 6721 ft., 5862 ft. and 5571 ft. dated 34.0 Ma, 33.0 Ma, 31.3 Ma, 28.1 Ma and 24.3  Ma and five candidate SBs at 6941 ft., 6029 ft., 5688 ft., 5653 ft. and 5542 ft. dated 32.4 Ma, 29.3 Ma, 27.3 Ma, 24.9 Ma and 23.7 Ma respectively. The correlation of the two wells and sequence stratigraphic interpretation is a supplementary understanding of the subsurface geology of the Onshore, western Niger Delta area of Nigeria. Keywords: Bio-stratigraphic data, Well logs, Sequence stratigraphy, Well correlation.

No abstract

The Early Cretaceous succession penetrated by Famo-1 well in Gongola sub Basin, Upper Benue Trough, Nigeria were analyzed for its palynological content. This investigation produced significant Pollen and Spore and the assemblage reveals the dominance of angiosperm Pollen grain and pteridophytes spore. Gymnosperm pollen was scarce and less varied. The studied interval penetrated a sequence of sandstone, sandy shale and mudstone occurring at different intervals in the studied section of the well. Established on the stratigraphic distribution of the palynomorphs recovered from Famo-1 well, three informal assemblage palynozones covering the Early Cretaceous were identified. The zones are: Assemblage Zones I & II (Cenomanian); Assemblage Zone III (Turonian -Santonian). The different zones signifies a time stratigraphic unit comparable to the identified lithostratigraphic units penetrated by the well. The age (Cenomanian -Santonian) determinations are based on the known stratigraphic ranges of pollen and spores and their relative stratigraphic positions. Data from the studied well revealed that there is relatively higher frequency of the land derived pollen and spores compared to marine palynomorph abundance, which suggests a paralic condition of continental to shallow marine environment. The shallow marginal marine environment is further sustained by the presence of foraminifera test linings at some depths which are indicative of marine palaeoenvironment (inner neritic environment). Interpretations from the spore and pollen assemblages reveal sediment deposition took place in a wet to arid climate condition in marginal marine to nearshore environment.