4 research outputs found

    Facies and Granulometric Analysis as Proxies for the Paleodepositional Environment of the Imo Formation, Southeastern Nigeria

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    Facies and granulometric analysis were carried out so as to decipher the paleodepositional environment of the Imo Formation in the study area. Results suggest the presence of eleven lithofacies, which are grouped into six lithofacies association, namely; swaly cross-bedded sandstone, laminated shale, sandstone / shale intercalations, bioturbated sandstone, fossiliferous shale and planar crossbedded sandstone facies associations. Results of pebble morphometric indices suggest a high energy (beach) environment for the sandstones of the Imo Formation. Pebble form indices for the formation have coefficient of flatness (F.R. %) =37.342 ± 8.916 (beach), elongation ratio (E.R.) = 0.743 ± 0.138 (torrents, brooks and rivulets), maximum projection sphericity index (M.P.S.I.) = 0.565 ± 0.090 (beach) and oblate - prolate index (OP index) = -2.313 ± 5.72 (beach). Scatter plots of coefficient of flatness versus sphericity and sphericity versus oblate-prolate index suggests that pebbles were formed in a shallow marine high energy (beach) environment. Bivariate plots of sand textural parameters such as graphic skewness versus graphic standard deviation and second moment skewness versus second moment standard deviation also confirm the high energy (beach) origin of sandstones. These results thus suggest a generalized spectrum of marine environments ranging from upper offshore through lower to upper shoreface to the foreshore for the Imo Formation Keywords: Imo Formation, Lithofacies, Sphericity, Oblate – Prolate Index, Coefficient of Flatnes

    Pebble Morphometric Study of the Ogwashi-Asaba Formation at Ubakala and Environs in Southeastern Nigeria

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    Pebble morphometric study was carried out for the Ogwashi-Asaba Formation so as to understand its paleodepositional environment. The three axes; the long (l), the intermediate (i) and the short (s) were measured for the two sets of one hundred and forty (140) and one hundred and fifty (150) pebbles collected from two outcrops of the Ogwashi-Asaba Formation. Pebble form indices such as Maximum Projection Sphericity (MPSI), coefficient of flatness (FR %), elongation ratio (ER) and oblate-prolate (OP) index were computed from these measurements. Roundness was estimated using Sames image sets. The mean values of the pebble form indices ranges from 49.78 to 52.02 for coefficient of flatness (FR %). 0.71 to 0.73 for sphericity, 2.60 t0 3.53 for oblate-prolate index, and 0.66 to 0.69 for elongation ratio. The calculated indices are suggestive of fluvial sedimentation for the Ogwashi-Asaba Formation. Bivariate plots of coefficient of flatness (FR %) versus maximum projection sphericity index (MPSI) and plots of sphericity (MPSI) versus oblate-prolate index (OP) are also indicative of fluvial origin. Scatter plots of roundness versus elongation ratio shows that 100% of the pebbles are in a littoral field. Plots of bivariate parameters such as simple skewness versus simple standard deviation, and second moment skewness versus second moment standard deviation  suggests the Ogwashi-Asaba Formation as a product of the fluvial depositional processes. Keywords: Niger Delta Basin, Ogwashi-Asaba Formation, Pebble morphometry, Pebble Form indices. DOI: 10.7176/JNSR/9-6-06 Publication date:March 31st 201

    The Paleoenvironmental Significance of Trace Fossils from the Paleocene Imo Formation, South-eastern Nigeria

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    Trace fossils and lithofacies associations were studied to understand the paleodepositional environment of the Paleocene Imo Formation. The methodology involves lithologic logging to obtain sedimentological and ichnological data. Bioturbation index were used to estimate the intensity of biotubation of the various lithofacies associations. The trace fossils observed in the Imo Formation includes Ophiomorpha and Altichnus belonging to the Skolithos ichnofacies and Chondrites, Thalassinoides, Planolites, and Rosselia which belongs to the Cruziana ichnofacies. Six lithofacies association were distinguished and interpreted as follows; swaly cross-stratified sandstone represents a middle shoreface environment, laminated shale representing offshore to lower shoreface transition sediments, interbedded sandstone and shale as well as bioturbated sandstone deposited in upper shoreface environments, fossiliferous shale representing an upper offshore deposit while crossbedded sandstone is inferred to as foreshore-upper shoreface sediments. The gross depositional environment suggests sediments deposited in shallow marine environments lying between the foreshore-shoreface to offshore depositional settings. Keywords: Trace fossils, Ichnofossils, Lithofacies, Imo Formation, Niger Delta Basi

    Geochemistry and Industrial Applications of Brown Coals of the Ogwashi-Asaba Formation in Parts of Anambra State, Nigeria

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    Geochemical studies have been carried out on brown coal of the Ogwashi-Asaba Formation in parts of Anambra State, Nigeria, using proximate and ultimate analytical results to evaluate its potentials for industrial utilization. An understanding of the physico-chemical characteristics such as moisture content    , volatile matter content, fixed carbon content, and ash content are essential for establishing the quality of the coal. The chemical analysis of the brown coal samples results suggest that fixed carbon varies from 1.51 to 37.50 wt%, moisture content varies from 2.40 to 39.80 wt%, volatile matter varies from 2.44 to 39.92 wt%, and ash content ranges from 6.60 to 70.75 wt%, carbon content ranges from 11.59 wt% to 59.33 wt%, oxygen content ranges from 0.06 to 13.87 wt%, hydrogen content ranges from 0.13 to 4.59 wt%, sulfur content varies from 0.04 to  2.48 wt% and the nitrogen content varies from 1.30% to 1.85 wt%. The high-moisture content poses several challenges for the utilization of lignite, because it lowers the energy density of the fuel and makes its transportation uneconomic over long distances. The analytical results show that the coal cannot be employed in the steel industry for the generation of substantial heat for the working of the furnace but can be used as a steam coal. Proximate analysis and calorific data suggest that the coal belongs to the lowest rank i.e. lignite. The brown coal is less hazardous to the ecosystem because of its significantly low sulfur and nitrogen contents. Based on the results of the study, the brown coal can be used for power generation, gasification, production of industrial chemicals and cement production. Keywords: Coal, Proximate Analysis, Ultimate Analysis, Calorific values DOI: 10.7176/JNSR/12-12-03 Publication date:June 30th 202
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