Facies Analysis and Paleoenvironmental Reconstruction of Well X, Onshore Niger Delta, Nigeria (Published)
Biofacies and lithofacies analysis of one hundred and ninety-two (192) ditch cutting rock samples from well x, onshore Niger Delta was carried out for the purpose of the paleoenvironmental reconstruction of the rock succession. The objectives were to identify the lithofacies units and species of foraminifera and to use both quantitave and qualitative foraminiferal assemblage to recognise the benthonic foraminiferal biofacies and integrate both results for delineation of paleobathymetric and paleoenvironmental settings of sediments penetrated by well x interval studied. The rock samples were prepared through wet-sieve analysis with 63µm mesh sieve size, and subsequently through dry-sieve analysis with 250µm and 500µm mesh sieve sizes. The prepared rock samples were analyzed to generate data for sedimentological grain-size analysis and foraminifera biofacies assemblages. The grain-size analysis provided lithofacies associations, sand/shale ratio and sorting/gradational profile for the studied intervals of well-x while the micropaleontological analysis identified a total of ninety-three (93) well preserved foraminiferal species from which three (3) biofacies associations were delineated. The biofacies include: Ammonia beccarii, Ammonia beccarii/Bolivina scalprata miocenica, and Haplophragmoides compressa/ Valvulina flexilis biofacies indicating Shallow Inner Neritic, Inner- Middle Neritic, and Outer Neritic – Upper Bathyal paleoenvironment respectively. The result of the sand/shale ratio and lithofacies associations indicated penetration into the Agbada Formation of the Niger delta and deposition within shallow to deep marine paleoenvironmental settings, predominantly as channels, intercalated with overbank and distal bar/bay deposits. Synthesis of the biofacies and lithofacies indicated stratigraphic development between coastal deltaic and upper bathyal paleowater depths.
Keywords: Niger-Delta, Onshore., biofacies, foraminifera, lithofacies, paleoenvironment
Foraminiferal Biostratigraphy of Well Ad, Western Niger Delta (Published)
Micropaleontological analysis of sixty (62) ditch cuttings rock samples collected from interval, 7800 feet to 12,002 feet of well AD, located offshore western Niger Delta was carried out for the investigation of their age and paleodepositional environment. Standard methods and techniques of foraminiferal sample processing and analysis were followed to disaggregate the microfauna from the rock matrix. The studied interval is predominantly made up of 80 to 100 % sandstone, minor shale and siltstone with variable textural properties. Foraminifera study revealed well preserved and diverse species dominated by the calcareous benthic forms. A total of seventy-four (74) foraminiferal species were recovered among which fifty (52) two are calcareous benthic, six (6) are agglutinating forms while sixteen (16) are planktonic foraminifera. On the basis of the faunal assemblage, abundance and diversity of the important foraminiferal events, four (4) foraminiferal zones (Valvulineria spp, Brizalina mandoroveensis, Hanzawaia concentrica and Lenticulina inornata) were recognised and correlated with F300 and F500 to assign an early to middle Miocene age for the sediments. Paleoenvironmental deductions were based primarily on the richness and diversity of foraminiferal species categories. The presence or absence of planktonic foraminifera aided in deciphering open ocean environments. The dominant biofacies associations recorded within the studied section of Well-AD is the Ammonia beccarii biofacies defined by the rare to common occurrences of Ammonia beccarii, Bolivina scalpratamiocenica, Florilus atlanticus and Epistominella vitrea. Brizalina mandoroveensis species, Lenticulina inornata, Hanzawaia strattoni, Eponides eshira, Cribroelphidium galvestonensis and Hanzawaia concentrica were also in association. The Ammonia beccarii biofacies is indicative of the Shallow/Inner Neritic Paleoenvironment, while the Inner Neritic/Middle Neritic Setting is characterized by top occurrence of Valvulineria spp, a rich continuous occurrence of Epistominella vitrea. The paleoenvironment of the studied section of Well-AD is dominantly inner to middle neritic with concomitant minor incursion of outer neritic setting.
Keywords: Age, Niger-Delta, foraminifera, micropaleontology, neritic, paleoenvironment
Late Paleocene-Early Eocene Benthic Foraminifera From the Esna Shale of Duwi Section, Red Sea Coast of Egypt (Published)
Issawi et al. (1999) distinguished detailed seven facies that characterized the upper Cretaceous-Paleogene sedimentary rocks of Egypt, from north to south: Sinai Facies (SF), Ataqa Facies (AF), North Western Desert Facies (NWDF), Southern Galala Facies (SGF), Farafra Bahariya Facies (FBF), Nile Valley Facies (NVF), Nuba Abu Ballas Facies (NABF), which suggest gradual paleogeographical changes from transitional open marine environmental facies in the northern Egypt to shallow shelf setting in the south due to paleorelief (highs and lows of the Syrian Arc System, Laramid Orogeny) in the upper Cretaceous. Each type facies has certain formations, which differ from the adjacent one, though some formations may cross the boundaries between two contiguous facies. According to these authors the contact between the deep (in the north) and shallow marine facies (in the south) nearly coincides around Lat. 28º N (but about Lat. 27º N of Anan, 1987). The studied Duwi section, Red Sea coast of Egypt, represents the Nile Valley Facies. The Tethyan aspect, Midway-Type Fauna (MTF) of middle-outer neritic environment (100-200 m) is interpreted for the Esna Shale of this section. This study deals with the paleontology and stratigraphy of sixty nine diagnostic benthic foraminiferal species were recorded from the upper Paleocene-early Eocene transition of the study section, and thirty seven species of them are illustrated. Its paleobiogeography distribution in different localities in the Northern and Southern Tethys is detected.
Keywords: Duwi section, Egypt, Esna Shale, Paleogene, Tethys., foraminifera