Abstract Several attempts at reconstructing geological settings and palaeoclimatic changes of the... more Abstract Several attempts at reconstructing geological settings and palaeoclimatic changes of the siliciclastic deposits of the Dahomey Basin, SW Nigeria, using relative age dating and correlation methods, have resulted in serious discrepancies on the ages. Therefore, a chronology framework established by an absolute age dating method is requisite to constrain the geological interpretation. This research focuses on quartz optically stimulated luminescence (OSL) dating of the upper siliciclastic sediments to help bridge the lacuna that arose from previous relative geologic dating. Ten sub-surface sediment samples were collected from the eastern part of the basin, and quartz OSL dating using single-aliquot regenerative-dose protocol was conducted for all the samples. The OSL signals appear well bleached prior to deposition and the OSL ages are reliable and robust. Through the application of OSL, the age framework of the uppermost part of sediments in the study area was established. The OSL dating results revealed that these depositional periods fall within the Holocene and are concentrated during two groups: 3.52 ka–1.55 ka, and 0.64 ka–0.05 ka. The samples with ages of 3.52 ka–1.55 ka distribute in the belt-like inland zone approximately parallel to the coastline. This deposition episode appears to be caused by the decrease in relative sea level during late Holocene. Thus, this study sheds light on the understanding past coast dynamics in the region.
The research aim is to determine the organic productivity and hydrocarbon potential of the expose... more The research aim is to determine the organic productivity and hydrocarbon potential of the exposed shale lithology along Uzebba road and Bawa hills near Auchi, Southwest Nigeria.Twenty two (22) shale samples were acquired from the study area; twelve (12) from the outcropping section along Uzebba road, and the remaining ten (10) samples obtained from Bawa hills. The samples were then subjected to organic geochemical analysis using Total Organic Carbon (TOC) and Rock Eval Pyrolysis to evaluate the organic enrichment, organic quality and thermal maturity espectively.Total Organic Carbon (TOC) content of the twenty-two samples ranges from 3.42 – 4.88 wt. %, affirming a high organic enrichment. Shale samples from Uzebba segment and Bawa hills falls within the Type I and Type II Kerogen class respectively. The former is indicative of immature – sub mature organic matter with no hydrocarbon formation prospect whilst the latter exhibits great hydrocarbon (oil) generation potential Thermal maturation assessment for both samples apparently ranges from immature to mature organic matter. From the Rock-Eval pyrolysis result, all the twenty-two (22) samples were confirmed to be organically enriched. However, the type I kerogen of Bawa at favourable geothermal gradient can potentially serve as a suitable source rock for petroleum generation.
The combination of mineralogical and geochemical data of sedimentary rock can reveal the nature o... more The combination of mineralogical and geochemical data of sedimentary rock can reveal the nature of source rocks, the tectonic settings of the sedimentary basins and the Paleoclimatic conditions. The aim of this research is to determine the geochemistry and mineralogy of the Imobi sandstones and to infer the provenance and possible depositional environment for these sand stones. Eight rock samples were collected from the study area, some portion were used for geochemical analysis to determine the chemical composition using X-ray fluorescence and the remaining portion were also used for mineralogical analysis to determine the mineralogical compositions and to estimate the modal percentages of minerals in the Imobi sandstone samples with the aid of the Petrological microscope. From the geochemical analysis, sixteen (16) elements and oxides were revealed and they includes SiO 2 , Al 2 O 3, Fe 2 O 3, CaO, V 2 O 5 , ZrO 2 , SO 3 , K 2 O, Br, P 2 O 5 , CuO, TiO 2 , MnO, Rb 2 O, As 2 O 3 , ...
Stratigraphic and geophysical analyses of an outcrop at Onikintibi were done with the aim of unde... more Stratigraphic and geophysical analyses of an outcrop at Onikintibi were done with the aim of understanding basin architecture and predicting depositional history. The palynological studies defined the age of the units, and clarified the lithology of the basal component. Three principal lithology types found are conglomeratic sands, compacted ferruginised sandstone, and the weathered basement; these units have resistivity values of >1000 m, >1019m and <400m. The basal layer is derived from porphyritic granite protolith. In addition, coarsening-upward stacking pattern of the reddish-brown conglomerate suggests prevalence of continental conditions. High thickness of the Ise units at the western edge suggests greater accommodation space and subsidence during basin development; consequently, the layer tapers to the east in response to waning current. The occurrence of Monoporites annulatus, Laevigatosporites and Acrostichum aureum imply the outcrop is post Paleocene. Longapertit...
Abstract: Outcrop analog are important tools for better understanding of large scale seismic feat... more Abstract: Outcrop analog are important tools for better understanding of large scale seismic features such as slope deposits and structures. Sedimentary exposures at Ijebu Omu, Itele and Ijebu Ife, all within the eastern part of Dahomey basin, Southwest Nigeria were ...
Organic geochemical analysis of two selected wells penetrating shale facies of the Anambra basin ... more Organic geochemical analysis of two selected wells penetrating shale facies of the Anambra basin was conducted with the view of evaluating the section in terms of quantity and quality of organic matter, genetic potential, organic matter type, thermal maturity as well as determining the type of hydrocarbon that could be generated. Geochemical parameters such as Total Organic Carbon (TOC), S1 (representing free and adsorbed hydrocarbons present), S2 (representing hydrocarbons generated directly from the kerogen), S3 (carbon dioxide CO2 present) and maximum temperature (Tmax) as well as Hydrogen Index (HI), Oxygen Index (OI), Production Index (PI) and Genetic Potential (GP) were derived and calculated from the pyrolysis data. Result indicated that Well 1 samples have an average TOC of 1.21 wt % which is considered good in organic matter quantity and fair in quality, while Well 2 samples are organically lean, poor in quantity and quality with average TOC value of 0.15 wt %. The Genetic ...
X-ray diffraction is a basic tool in mineralogical analysis of sediments, and in the case of fine... more X-ray diffraction is a basic tool in mineralogical analysis of sediments, and in the case of fine grained sediments an essential one. Understanding of rocks composition, the nature of clay mineralogy content and provenance is very important in Basin evaluation. This study therefore focuses on the use of X-ray diffraction to study the clay stone unit exposed along Igbile, southwestern Nigeria. Five clay stone samples were collected following fieldwork in the study area and were subjected to X-ray Diffraction analysis. This was done in order to delineate the associated mineral composition in the rock samples, determine the crystal forms and shape of the mineral and probably provenance of the mineral content. Observations from the result of the X-ray Diffraction indicated peaks with d-spacing range of 1.488Å, 1.63 Å, 1.59 Å, 1.62 Å and 7.17 Å indicative of Kaolinite and d-spacing range of 1.541Å, 1.817 Å, 2.282 Å, 2.458 Å, 3.343 Å and 4.26 Å indicative of quartz as the only significant...
A geochemical study of Nkalagu limestone of the Lower Benue Trough as exposed at Nigeria Cement C... more A geochemical study of Nkalagu limestone of the Lower Benue Trough as exposed at Nigeria Cement Company (NIGERCEM) was carried out. The study aims at the determination of major oxides and trace elements of the limestone exposed in the quarry using X–Ray Fluorescence Spectrophotometer (XRF) and Atomic Absorption Spectrophotometer (AAS) respectively as well as reconstructing the depositional history of the deposit. Petrographic study was also done to enhance the determination of biogenic contents of the deposit. Results of fifteen (15) samples collected for analysis put the range major
The rise in demand for natural gas has spurred the need to investigate the inland sedimentary bas... more The rise in demand for natural gas has spurred the need to investigate the inland sedimentary basin for more potential sources. In response, the petrophysical parameters of the carbonaceous shale samples from two deep boreholes of Anambra Basin were evaluated. The gas-prone nature of Nkporo shale showed a thermal evolution of a Type III kerogen with initial HI value between 650 and 800 mgHC/gTOC, S2/S3 < 1, a maximum Tmax value of 488°C and have a low hydrocarbon generation potential ranging from 0.07 to 0.15. However, the average TOC content (2.21 wt%) indicated a good source rocks for hydrocarbon since it exceeds threshold limit of 0.5%. The plot of HI against Tmax shows that the organic matter belongs to the Type-III kerogen which reflects the capability of the Npkoro Formation to generate more natural gas than oil compared to Type-II kerogen. The high values (>3) of pristane/phytane ratio in both wells indicated that the organic matter belongs to terrigenous source deposit...
Abstract Several attempts at reconstructing geological settings and palaeoclimatic changes of the... more Abstract Several attempts at reconstructing geological settings and palaeoclimatic changes of the siliciclastic deposits of the Dahomey Basin, SW Nigeria, using relative age dating and correlation methods, have resulted in serious discrepancies on the ages. Therefore, a chronology framework established by an absolute age dating method is requisite to constrain the geological interpretation. This research focuses on quartz optically stimulated luminescence (OSL) dating of the upper siliciclastic sediments to help bridge the lacuna that arose from previous relative geologic dating. Ten sub-surface sediment samples were collected from the eastern part of the basin, and quartz OSL dating using single-aliquot regenerative-dose protocol was conducted for all the samples. The OSL signals appear well bleached prior to deposition and the OSL ages are reliable and robust. Through the application of OSL, the age framework of the uppermost part of sediments in the study area was established. The OSL dating results revealed that these depositional periods fall within the Holocene and are concentrated during two groups: 3.52 ka–1.55 ka, and 0.64 ka–0.05 ka. The samples with ages of 3.52 ka–1.55 ka distribute in the belt-like inland zone approximately parallel to the coastline. This deposition episode appears to be caused by the decrease in relative sea level during late Holocene. Thus, this study sheds light on the understanding past coast dynamics in the region.
The research aim is to determine the organic productivity and hydrocarbon potential of the expose... more The research aim is to determine the organic productivity and hydrocarbon potential of the exposed shale lithology along Uzebba road and Bawa hills near Auchi, Southwest Nigeria.Twenty two (22) shale samples were acquired from the study area; twelve (12) from the outcropping section along Uzebba road, and the remaining ten (10) samples obtained from Bawa hills. The samples were then subjected to organic geochemical analysis using Total Organic Carbon (TOC) and Rock Eval Pyrolysis to evaluate the organic enrichment, organic quality and thermal maturity espectively.Total Organic Carbon (TOC) content of the twenty-two samples ranges from 3.42 – 4.88 wt. %, affirming a high organic enrichment. Shale samples from Uzebba segment and Bawa hills falls within the Type I and Type II Kerogen class respectively. The former is indicative of immature – sub mature organic matter with no hydrocarbon formation prospect whilst the latter exhibits great hydrocarbon (oil) generation potential Thermal maturation assessment for both samples apparently ranges from immature to mature organic matter. From the Rock-Eval pyrolysis result, all the twenty-two (22) samples were confirmed to be organically enriched. However, the type I kerogen of Bawa at favourable geothermal gradient can potentially serve as a suitable source rock for petroleum generation.
The combination of mineralogical and geochemical data of sedimentary rock can reveal the nature o... more The combination of mineralogical and geochemical data of sedimentary rock can reveal the nature of source rocks, the tectonic settings of the sedimentary basins and the Paleoclimatic conditions. The aim of this research is to determine the geochemistry and mineralogy of the Imobi sandstones and to infer the provenance and possible depositional environment for these sand stones. Eight rock samples were collected from the study area, some portion were used for geochemical analysis to determine the chemical composition using X-ray fluorescence and the remaining portion were also used for mineralogical analysis to determine the mineralogical compositions and to estimate the modal percentages of minerals in the Imobi sandstone samples with the aid of the Petrological microscope. From the geochemical analysis, sixteen (16) elements and oxides were revealed and they includes SiO 2 , Al 2 O 3, Fe 2 O 3, CaO, V 2 O 5 , ZrO 2 , SO 3 , K 2 O, Br, P 2 O 5 , CuO, TiO 2 , MnO, Rb 2 O, As 2 O 3 , ...
Stratigraphic and geophysical analyses of an outcrop at Onikintibi were done with the aim of unde... more Stratigraphic and geophysical analyses of an outcrop at Onikintibi were done with the aim of understanding basin architecture and predicting depositional history. The palynological studies defined the age of the units, and clarified the lithology of the basal component. Three principal lithology types found are conglomeratic sands, compacted ferruginised sandstone, and the weathered basement; these units have resistivity values of >1000 m, >1019m and <400m. The basal layer is derived from porphyritic granite protolith. In addition, coarsening-upward stacking pattern of the reddish-brown conglomerate suggests prevalence of continental conditions. High thickness of the Ise units at the western edge suggests greater accommodation space and subsidence during basin development; consequently, the layer tapers to the east in response to waning current. The occurrence of Monoporites annulatus, Laevigatosporites and Acrostichum aureum imply the outcrop is post Paleocene. Longapertit...
Abstract: Outcrop analog are important tools for better understanding of large scale seismic feat... more Abstract: Outcrop analog are important tools for better understanding of large scale seismic features such as slope deposits and structures. Sedimentary exposures at Ijebu Omu, Itele and Ijebu Ife, all within the eastern part of Dahomey basin, Southwest Nigeria were ...
Organic geochemical analysis of two selected wells penetrating shale facies of the Anambra basin ... more Organic geochemical analysis of two selected wells penetrating shale facies of the Anambra basin was conducted with the view of evaluating the section in terms of quantity and quality of organic matter, genetic potential, organic matter type, thermal maturity as well as determining the type of hydrocarbon that could be generated. Geochemical parameters such as Total Organic Carbon (TOC), S1 (representing free and adsorbed hydrocarbons present), S2 (representing hydrocarbons generated directly from the kerogen), S3 (carbon dioxide CO2 present) and maximum temperature (Tmax) as well as Hydrogen Index (HI), Oxygen Index (OI), Production Index (PI) and Genetic Potential (GP) were derived and calculated from the pyrolysis data. Result indicated that Well 1 samples have an average TOC of 1.21 wt % which is considered good in organic matter quantity and fair in quality, while Well 2 samples are organically lean, poor in quantity and quality with average TOC value of 0.15 wt %. The Genetic ...
X-ray diffraction is a basic tool in mineralogical analysis of sediments, and in the case of fine... more X-ray diffraction is a basic tool in mineralogical analysis of sediments, and in the case of fine grained sediments an essential one. Understanding of rocks composition, the nature of clay mineralogy content and provenance is very important in Basin evaluation. This study therefore focuses on the use of X-ray diffraction to study the clay stone unit exposed along Igbile, southwestern Nigeria. Five clay stone samples were collected following fieldwork in the study area and were subjected to X-ray Diffraction analysis. This was done in order to delineate the associated mineral composition in the rock samples, determine the crystal forms and shape of the mineral and probably provenance of the mineral content. Observations from the result of the X-ray Diffraction indicated peaks with d-spacing range of 1.488Å, 1.63 Å, 1.59 Å, 1.62 Å and 7.17 Å indicative of Kaolinite and d-spacing range of 1.541Å, 1.817 Å, 2.282 Å, 2.458 Å, 3.343 Å and 4.26 Å indicative of quartz as the only significant...
A geochemical study of Nkalagu limestone of the Lower Benue Trough as exposed at Nigeria Cement C... more A geochemical study of Nkalagu limestone of the Lower Benue Trough as exposed at Nigeria Cement Company (NIGERCEM) was carried out. The study aims at the determination of major oxides and trace elements of the limestone exposed in the quarry using X–Ray Fluorescence Spectrophotometer (XRF) and Atomic Absorption Spectrophotometer (AAS) respectively as well as reconstructing the depositional history of the deposit. Petrographic study was also done to enhance the determination of biogenic contents of the deposit. Results of fifteen (15) samples collected for analysis put the range major
The rise in demand for natural gas has spurred the need to investigate the inland sedimentary bas... more The rise in demand for natural gas has spurred the need to investigate the inland sedimentary basin for more potential sources. In response, the petrophysical parameters of the carbonaceous shale samples from two deep boreholes of Anambra Basin were evaluated. The gas-prone nature of Nkporo shale showed a thermal evolution of a Type III kerogen with initial HI value between 650 and 800 mgHC/gTOC, S2/S3 < 1, a maximum Tmax value of 488°C and have a low hydrocarbon generation potential ranging from 0.07 to 0.15. However, the average TOC content (2.21 wt%) indicated a good source rocks for hydrocarbon since it exceeds threshold limit of 0.5%. The plot of HI against Tmax shows that the organic matter belongs to the Type-III kerogen which reflects the capability of the Npkoro Formation to generate more natural gas than oil compared to Type-II kerogen. The high values (>3) of pristane/phytane ratio in both wells indicated that the organic matter belongs to terrigenous source deposit...
Uploads
Papers