Palynostratigraphy of miocene through Pleistocene Sediments from Part of the Western Niger Delta, Nigeria
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Date
2010-10
Authors
Durugbo, E.U
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Abstract
Palynological analyses were carried out on four wells, Bentu-DX, Eze-DX, Meren-66 and Meren-67 from the Western Niger Delta. The palynomorphs recovered were abundant and diverse in the horizons studied. The Bentu-DX and Eze-DX wells are of Late Miocene (P860) – Late Pleistocene (P900) age (ca. 5.8Ma -1.3Ma). The assemblages are dominated by land derived palynomorphs particularly Monoporites annulatus, the mangrove pollen Zonocostites ramonae, Podocarpus milanjianus, Stereisporites spp., Cyperaceaepollis spp., Sapotaceoidaepollenites spp., Nympheaepollis clarus, Psilatricolporites crassus, Retitricolporites irregularis and pteridophyte spores, in association with abundant records of dinoflagellate cysts especially in the Bentu-DX well. The commonest species were Polysphaeridium zoharyi, Operculodinium centrocarpum, Spiniferites ramosus, Achomosphaera ramulifera, Hystrichokolpoma rigaudiae, Lingulodinium macahaerophorum, Spiniferites mirabilis, Spiniferites membranaceus, Spiniferites delicatus, Spiniferites bulloideus, Spiniferites elongatus, Achomosphaera ramulifera, Achomosphaera spp., Selenopemphix nephroides, Selenopemphix spp., Achomosphaera andalousiensis and the acritarch Leiosphaeridia spp. Fewer dinocysts were recovered in the Eze-DX well. A predominantly dry climate is inferred for these sediments due to the abundance of savanna species, and the preponderance of the dinoflagellate cysts Polysphaeridium zoharyi and Operculodinium centrocarpum, species adapted to very saline and warm waters. These dinoflagellate cysts clustered between the 2.0Ma -3.4Ma denoting the glacial maxima events during these periods. On the other hand, the Meren-66 and Meren-67 wells were of Middle Miocene (P720) – Earliest Pliocene (P870) age (ca. 15.0Ma - <5.0Ma). Land derived palynomorphs dominated the assemblages together with a Peridinalean dominated dinoflagellate cysts assemblage characterized by common records of the Oceanic species Nematosphaeropsis labyrinthus with Selenopemphix nephroides, Lingulodinium macahaerophorum, Selenopemphix spp., Homotryblium spp., Sumatradinium spp., Xandarodinium spp., and Lejeunecysta spp. A predominantly wet climate is inferred for these sediments due to the dominance of mangrove, freshwater swamp, brackish water swamp, Palmae and lowland rainforest species. The common records of paleoenvironmental indicators such as Neritic - Oceanic dinoflagellate cysts, microforaminiferal wall linings, freshwater algae Botryococcus braunii and Pediastrum spp., in the studied wells suggested sediment deposition in a shallow to deep marine environments with frequent freshwater incursions. Palynological events offered hope of being used in delineating chronostratigraphic surfaces. Plants of the Asteraceae, Leguminosaceae, Euphorbiaceae, and Rubiaceae families dominated the assemblages of the studied wells.
Description
A Thesis Submitted to the School of Postgraduate Studies, University of Lagos
Keywords
Palynological analyses , palynomorphs , Botany , Research Subject Categories::NATURAL SCIENCES::Biology::Organism biology
Citation
Durugbo, E.U (2010). Palynostratigraphy of miocene through Pleistocene Sediments from Part of the Western Niger Delta, Nigeria. A Thesis Submitted to University of Lagos School of Postgraduate Studies Phd Thesis and Dissertation, 376pp.