Landslide is a geological hazard typically associated with extreme events such as earthquakes,heavy rainfall,volcanic eruptions,changes in groundwater level,etc.This study was carried out in Okemesi-Ekiti(also known a...Landslide is a geological hazard typically associated with extreme events such as earthquakes,heavy rainfall,volcanic eruptions,changes in groundwater level,etc.This study was carried out in Okemesi-Ekiti(also known as Okemesi),Southwest Nigeria,with the purpose of using remote sensing and GIS technologies to analyze the environmental factors(grain size,direct shear strength resistance,rainfall data,wet density,surface,and slope)resulting in the occurrence of the Okemesi landslide.The study also aimed to conduct a vulnerability analysis in the study area to identify regions with a probability of landslide occurrence.The grain size analysis of the soil in the Okemesi landslide area showed that slope materials comprised 17.14%gravel,59.31%sand,and 19.48%fines,thus the soil type could be classified as poorly graded gravely sand with a high possibility of landslide occurrence.The geomorphic characteristics of the study area was characterized by slopes ranging from 0.00°to 49.00°,while most slopes in the area were less than 8.00°.The slope aspect direction was mainly in south(157.51°–202.50°),southwest(202.51°–247.50°),west(247.51°–292.50°),and north(0.00°–22.50°and 337.51°–360.00°).The highlands were primarily bounded by the slope directions of north(0.00°–22.50°and 337.51°–360.00°),northeast(22.51°–67.50°),east(67.51°–112.51°),and southeast(112.51°–157.50°),which indicated the potential direction of mass movement.The study area can be divided into three vulnerability zones:high,medium,and low,with the area percentages of 9.00%,61.80%,and 29.20%,respectively.The analysis suggested that the Okemesi landslide was likely triggered by rainfall,which might have weakened the physical structure of slope materials.Understanding the causes and impacts of landslides is crucial for policymakers to implement measures to mitigate landslide hazards,protect infrastructure,and prevent the loss of life in the landslide-prone regions.展开更多
The Benin and Western Nigeria Offshore Basins, which are parts of an extensive basin called the Dahomey (Benin) Embayment, were formed during the Early Cretaceous under similar tectonic conditions and continental sedi...The Benin and Western Nigeria Offshore Basins, which are parts of an extensive basin called the Dahomey (Benin) Embayment, were formed during the Early Cretaceous under similar tectonic conditions and continental sedimentary environments. Based mainly on available lithological, biostratigraphic and paleoenvironmental data, this paper summarizes the stratigraphic succession of theses basins and attempts a comparison of these stratigraphic nomenclatures. The bulk of data shows that sedimentation begins with terrestrial at the base, passes through shallow marine, deep marine (with restrictive bottom circulation) and ends with open deep marine conditions. The stratigraphy of the Offshore Benin Basin was established later and considering lithological and paleontological similarities with formations of various southern Nigeria basins, the stratigraphic chart adopted for this basin was a mixed variant of various Southern Nigerian basins nomenclatures. For the first time, a correlation of stratigraphic charts of each basins and a schematic cross section showing their lithostratigraphic units, especially the Cretaceous-Paleocene interval which is petroliferous, are proposed. The study shows that the nomenclature adopted in Benin Republic must be revised by using type section/locality names for some particular Formations and widely accepted Formations names of Nigeria for the others. This will permit to avoid confusions as it is presently the case for the name “Afowo Formation” representing a Cretaceous sequence in Nigeria and which is use in Benin Republic to distinguish some sediments of Miocene age. Moreover, a High Resolution Biostratigraphy summary (including micropaleontology, nannopaleontology and palynology distributions) relating to each offshore basin is needed for sequences correlations and entire harmonization of the stratigraphic nomenclature of these offshore basins.展开更多
The Benue Trough has been known to have great potential for resources such as coal, hydrocarbon, limestone, barite, gypsum, etc. The study area is Maiganga coal mine located at Gombe, Gongola Basin, northern Benue Tro...The Benue Trough has been known to have great potential for resources such as coal, hydrocarbon, limestone, barite, gypsum, etc. The study area is Maiganga coal mine located at Gombe, Gongola Basin, northern Benue Trough in northeast Nigeria. Two coal seams, shales, siltstones, sandstones, and intercalation of ironstones make up the stratigraphic succession of 35 m thick. The coal is currently being exploited as a source of fuel at the Ashaka Cement Factory, Ashaka, Gombe state. Elemental and proximate analyses of the coal samples were carried out to investigate coking potential, acid generation potential and its suitability as a source of fuel. The paleodepositional condition and the original plant that form the coal were also examined. The proximate analysis showed that the moisture content ranges from 9.55% - 11.13%, volatile matter (40.88% - 44.89% dry), ash (5.29% - 13.99% dry), fixed carbon (41.30% - 53.41% dry) and calorific value (5469 - 6452 kcal/kg). Average values of the major elements;K<sub>2</sub>O, MgO and Fe<sub>2</sub>O<sub>3</sub> are low but a high loss on ignition was obtained for the coal ash. The samples recorded low concentrations in the trace elements, except for Ni, Cu, Ba, Sr, and Zr. Coal seam A exhibits negative europium anomaly and positive cerium anomaly indicating peat vegetation (<em>Sphagnum L.</em>) while coal Seam B showed negative cerium anomaly indicating soil grown plants (Mangrove and<em> Vicia villossa</em>). The present investigation showed that the coals were deposited in fluvial to paralic environments. The coals are not suitable for coking but have potential as a source of fuel and power generation.展开更多
Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometal...Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometallurgical processing of manganese from its ore, the leach liquors often contain divalent ions such as iron, manganese, copper, nickel, cobalt and zinc along with other impurities which make manganese very difficult to separate. The processes employed for solution concentration and purification in the hydrometallurgical processing of manganese include precipitation, cementation, solvent extraction and ion exchange. Solvent extraction also proves more efficient and it plays vital roles in the purification and separation of the manganese as compared to all other techniques. A detailed review of the various steps involved in the hydrometal-lurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.展开更多
This study was carried out to quantify uncertainty in the reserve estimate of hydrocarbon in the reservoirs of AD Field, offshore, Niger Delta. Three Dimensional (3D) seismic data and log suites of seven wells (AD1 to...This study was carried out to quantify uncertainty in the reserve estimate of hydrocarbon in the reservoirs of AD Field, offshore, Niger Delta. Three Dimensional (3D) seismic data and log suites of seven wells (AD1 to AD7), gamma ray, resistivity, neutron and bulk density logs, well deviation and checkshot data in AD Field acquired from companies in the area. Twelve faults (Fault1 to Fault12) were identified from seismic structural interpretation while Six hydrocarbon-bearing sand intervals (Sand A - F) were delineated from the petrophysical analysis. The sand intervals thin-out basin wards, suggesting a prograding sequence. The porosity of the sand intervals ranges between 0.19 and 0.32, implying good to excellent porosity. The water saturation values ranged from 0.19 to 0.39, indicates a prospective accumulation of hydrocarbon. Sand A reservoir had the largest accumulation of hydrocarbon in-place with hydrocarbon pore volume of 2343 106 Reserve Barrel (RB), Stock Tank Oil-Initially-In-Place (STOIIP) of 175 MMbbl and gas initially-in-place of 0.30 TCF. The coefficient of variation in the reserve estimates of the reservoirs ranged from 0.09 to 0.15 indicating very low uncertainty of substantial hydrocarbon reserve that could be exploited.展开更多
The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The che...The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy （Ea） of 32.92 kJ.mo1-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.展开更多
Sedimentological and foraminiferal paleoecological studies were carried out for the Oligocene-Miocene Ogwashi-Asaba Formation of the Anambra Basin at the Issele-Uku area in southern Nigeria,to reconstruct paleoenviron...Sedimentological and foraminiferal paleoecological studies were carried out for the Oligocene-Miocene Ogwashi-Asaba Formation of the Anambra Basin at the Issele-Uku area in southern Nigeria,to reconstruct paleoenvironments.The pattern of rock successions and textural characteristics suggest the prevalence of fluvio-deltaic setting during the formation of lignites and clastic rocks of Ogwashi-Asaba Formation.Agglutinated benthic foraminiferal species such as Ammotium sp.,Textularia sp.,Gavelinella sp.,Milliamina sp.,Reophax sp.,Bolivina sp.,Eponides sp.,Pseudobolivina sp.and Lenticulina sp.dominate the shale units whereas the planktonic forms are absent.All these species have very low population and diversity in the shales,which could be due to the presence of harsh conditions such as low oxygen level and scarcity of food,leading to poor survival.The assessments of benthic foraminifera's habitat suggest middle-to-inner neritic marine environment for the shales.Granulometric results suggest fluvial environment for the sandstone and deltaic for the lignite.The Ogwashi-Asaba Formation in Issele-Uku area of Anambra Basin,southern Nigeria,therefore,have records of shallow marine,and fluvio-deltaic paleoenvironments.展开更多
基金the Tertiary Education Fund(TETFUND),Nigeria,for funding this project。
文摘Landslide is a geological hazard typically associated with extreme events such as earthquakes,heavy rainfall,volcanic eruptions,changes in groundwater level,etc.This study was carried out in Okemesi-Ekiti(also known as Okemesi),Southwest Nigeria,with the purpose of using remote sensing and GIS technologies to analyze the environmental factors(grain size,direct shear strength resistance,rainfall data,wet density,surface,and slope)resulting in the occurrence of the Okemesi landslide.The study also aimed to conduct a vulnerability analysis in the study area to identify regions with a probability of landslide occurrence.The grain size analysis of the soil in the Okemesi landslide area showed that slope materials comprised 17.14%gravel,59.31%sand,and 19.48%fines,thus the soil type could be classified as poorly graded gravely sand with a high possibility of landslide occurrence.The geomorphic characteristics of the study area was characterized by slopes ranging from 0.00°to 49.00°,while most slopes in the area were less than 8.00°.The slope aspect direction was mainly in south(157.51°–202.50°),southwest(202.51°–247.50°),west(247.51°–292.50°),and north(0.00°–22.50°and 337.51°–360.00°).The highlands were primarily bounded by the slope directions of north(0.00°–22.50°and 337.51°–360.00°),northeast(22.51°–67.50°),east(67.51°–112.51°),and southeast(112.51°–157.50°),which indicated the potential direction of mass movement.The study area can be divided into three vulnerability zones:high,medium,and low,with the area percentages of 9.00%,61.80%,and 29.20%,respectively.The analysis suggested that the Okemesi landslide was likely triggered by rainfall,which might have weakened the physical structure of slope materials.Understanding the causes and impacts of landslides is crucial for policymakers to implement measures to mitigate landslide hazards,protect infrastructure,and prevent the loss of life in the landslide-prone regions.
文摘The Benin and Western Nigeria Offshore Basins, which are parts of an extensive basin called the Dahomey (Benin) Embayment, were formed during the Early Cretaceous under similar tectonic conditions and continental sedimentary environments. Based mainly on available lithological, biostratigraphic and paleoenvironmental data, this paper summarizes the stratigraphic succession of theses basins and attempts a comparison of these stratigraphic nomenclatures. The bulk of data shows that sedimentation begins with terrestrial at the base, passes through shallow marine, deep marine (with restrictive bottom circulation) and ends with open deep marine conditions. The stratigraphy of the Offshore Benin Basin was established later and considering lithological and paleontological similarities with formations of various southern Nigeria basins, the stratigraphic chart adopted for this basin was a mixed variant of various Southern Nigerian basins nomenclatures. For the first time, a correlation of stratigraphic charts of each basins and a schematic cross section showing their lithostratigraphic units, especially the Cretaceous-Paleocene interval which is petroliferous, are proposed. The study shows that the nomenclature adopted in Benin Republic must be revised by using type section/locality names for some particular Formations and widely accepted Formations names of Nigeria for the others. This will permit to avoid confusions as it is presently the case for the name “Afowo Formation” representing a Cretaceous sequence in Nigeria and which is use in Benin Republic to distinguish some sediments of Miocene age. Moreover, a High Resolution Biostratigraphy summary (including micropaleontology, nannopaleontology and palynology distributions) relating to each offshore basin is needed for sequences correlations and entire harmonization of the stratigraphic nomenclature of these offshore basins.
文摘The Benue Trough has been known to have great potential for resources such as coal, hydrocarbon, limestone, barite, gypsum, etc. The study area is Maiganga coal mine located at Gombe, Gongola Basin, northern Benue Trough in northeast Nigeria. Two coal seams, shales, siltstones, sandstones, and intercalation of ironstones make up the stratigraphic succession of 35 m thick. The coal is currently being exploited as a source of fuel at the Ashaka Cement Factory, Ashaka, Gombe state. Elemental and proximate analyses of the coal samples were carried out to investigate coking potential, acid generation potential and its suitability as a source of fuel. The paleodepositional condition and the original plant that form the coal were also examined. The proximate analysis showed that the moisture content ranges from 9.55% - 11.13%, volatile matter (40.88% - 44.89% dry), ash (5.29% - 13.99% dry), fixed carbon (41.30% - 53.41% dry) and calorific value (5469 - 6452 kcal/kg). Average values of the major elements;K<sub>2</sub>O, MgO and Fe<sub>2</sub>O<sub>3</sub> are low but a high loss on ignition was obtained for the coal ash. The samples recorded low concentrations in the trace elements, except for Ni, Cu, Ba, Sr, and Zr. Coal seam A exhibits negative europium anomaly and positive cerium anomaly indicating peat vegetation (<em>Sphagnum L.</em>) while coal Seam B showed negative cerium anomaly indicating soil grown plants (Mangrove and<em> Vicia villossa</em>). The present investigation showed that the coals were deposited in fluvial to paralic environments. The coals are not suitable for coking but have potential as a source of fuel and power generation.
文摘Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometallurgical processing of manganese from its ore, the leach liquors often contain divalent ions such as iron, manganese, copper, nickel, cobalt and zinc along with other impurities which make manganese very difficult to separate. The processes employed for solution concentration and purification in the hydrometallurgical processing of manganese include precipitation, cementation, solvent extraction and ion exchange. Solvent extraction also proves more efficient and it plays vital roles in the purification and separation of the manganese as compared to all other techniques. A detailed review of the various steps involved in the hydrometal-lurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.
文摘This study was carried out to quantify uncertainty in the reserve estimate of hydrocarbon in the reservoirs of AD Field, offshore, Niger Delta. Three Dimensional (3D) seismic data and log suites of seven wells (AD1 to AD7), gamma ray, resistivity, neutron and bulk density logs, well deviation and checkshot data in AD Field acquired from companies in the area. Twelve faults (Fault1 to Fault12) were identified from seismic structural interpretation while Six hydrocarbon-bearing sand intervals (Sand A - F) were delineated from the petrophysical analysis. The sand intervals thin-out basin wards, suggesting a prograding sequence. The porosity of the sand intervals ranges between 0.19 and 0.32, implying good to excellent porosity. The water saturation values ranged from 0.19 to 0.39, indicates a prospective accumulation of hydrocarbon. Sand A reservoir had the largest accumulation of hydrocarbon in-place with hydrocarbon pore volume of 2343 106 Reserve Barrel (RB), Stock Tank Oil-Initially-In-Place (STOIIP) of 175 MMbbl and gas initially-in-place of 0.30 TCF. The coefficient of variation in the reserve estimates of the reservoirs ranged from 0.09 to 0.15 indicating very low uncertainty of substantial hydrocarbon reserve that could be exploited.
文摘The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy （Ea） of 32.92 kJ.mo1-1 was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.
文摘Sedimentological and foraminiferal paleoecological studies were carried out for the Oligocene-Miocene Ogwashi-Asaba Formation of the Anambra Basin at the Issele-Uku area in southern Nigeria,to reconstruct paleoenvironments.The pattern of rock successions and textural characteristics suggest the prevalence of fluvio-deltaic setting during the formation of lignites and clastic rocks of Ogwashi-Asaba Formation.Agglutinated benthic foraminiferal species such as Ammotium sp.,Textularia sp.,Gavelinella sp.,Milliamina sp.,Reophax sp.,Bolivina sp.,Eponides sp.,Pseudobolivina sp.and Lenticulina sp.dominate the shale units whereas the planktonic forms are absent.All these species have very low population and diversity in the shales,which could be due to the presence of harsh conditions such as low oxygen level and scarcity of food,leading to poor survival.The assessments of benthic foraminifera's habitat suggest middle-to-inner neritic marine environment for the shales.Granulometric results suggest fluvial environment for the sandstone and deltaic for the lignite.The Ogwashi-Asaba Formation in Issele-Uku area of Anambra Basin,southern Nigeria,therefore,have records of shallow marine,and fluvio-deltaic paleoenvironments.
