Hydraulic, textural and geochemical characteristics of the Ajali Formation, Anambra Basin, Nigeria: implication for groundwater quality

Tijani, Moshood N.; Nton, M. E.

doi:10.1007/s00254-008-1196-1

Cited by 19 publications

(11 citation statements)

References 34 publications

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“…However, Ni concentration value is slightly above the maximum recommended value by WHO in 3 wells in location WL20, WL15 and WL4. Elevated trace metals concentrations in soils and shallow groundwater systems have been attributed to anthropogenic sources through agricultural practices (Abimbola et al, 1999: Mapanda et al, 2005Tijani et al, 2009;Tijani, 2010) the possibility of geogenic contribution is high considering the presence of a basic rock unit associated with the gneisses in the area. The relatively higher electrical conductivity with a range of 50μs/cm to1054μs/cm in the groundwater compared to a range of 25 μs/cm to 535μs/cm in the surface water may also be due to increased water rock reaction and dissolution of solid components of the bed rock.…”

Section: Resultsmentioning

confidence: 99%

Geochemical Characteristics and Quality of Groundwater Around Okemesi Fold Belt, South Western Nigeria

Okunlola

Afolabi²

2015

ENRR

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This study involves the determination of the hydrochemical character and quality of springs, shallow and deep wells around the Okemesi fold belt, south western Nigeria. This is with a view to elucidate their nature, type and evaluate portability, and suitability for agricultural and industrial purposes. The Okemesi fold belt is underlain by schistose rocks, mainly mica schist, quartz schist, and quartzite with minor amphibolites and gneisses. The major hydrochemical water type are Na-(K)-Cl-(SO 4) and Ca-(Mg)-(Cl)-SO 4 water facies constituting about 52% and 47% respectively. The study showed that almost all of the physico-chemical parameters such as total dissolved solid TDS (18.75-790.50 mg/l), electrical conductivity EC (25-1054 μs/cm), pH (5.4-7.4), temperature (24.8-29.5°C), turbidity (2.2-40.5 N.T.U), total hardness (10-274 mg/l), total alkalinity (18-274 mg/l), dissolved oxygen (1.8-7 mg/l), chlorine demand (1.56-4.75 mg/l); and bacteriological analysis (5-80 MPN) results were within the World Health Organization (WHO) limits recommended for drinking water. However, some groundwater samples have Ni + and K + concentrations slightly above the recommended standard. These physico-chemical parameters, especially cations: Ca 2+ (1.6-72.8 mg/l), Mg 2+ (0-4.39 mg/l), Na + (1.63-75.0 mg/l), K + (0-108.3 mg/l) , Si (4.0-10 mg/l), Cu (0-0.391 mg/l), Zn (0-0.29 mg/l), Cd (0-0 mg/l), Pb (0-0 mg/l), Fe (0.1-0.1 mg/l), Ni (0-0.043 mg/l) and anions such as HCO 3 (6.1-79.3 mg/l), Cl-(5-109 mg/l), SO 4 2-(38-76 mg/l), NO 3 2-(0-0 mg/l) and PO 4 3-(0.005-0.03 mg/l) seem to reflect the chemical nature of the underlying rock units suggesting dissolution, weathering and water-soil / rock interaction processes.

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Section: Resultsmentioning

confidence: 99%

Geochemical Characteristics and Quality of Groundwater Around Okemesi Fold Belt, South Western Nigeria

Okunlola

Afolabi²

2015

ENRR

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“…Akpokodje et al (2010) observed that the friable nature of the Ajali Sandstone and groundwater dynamics in the areas of vulnerability predispose the sediments to erosion. The preponderance of hydraulic, textural, and geochemical evidence described in Tijani and Nton (2009) suggests that the sandstones are prone to gulling.…”

Section: Icl/ipl Activitiesmentioning

confidence: 93%

“…The physical and chemical properties of the sandstone qualify it as a good source of portable groundwater. Tijani andNton (2009, 2010) reported that the sandstones are moderate to well-sorted, with graphic mean grain size of 0.23-0.53 mm. The estimated hydraulic conductivity was in the range of 1.4×10 −3 to 8.1×10 −5 m/s.…”

Section: Icl/ipl Activitiesmentioning

confidence: 98%

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The study of the factors controlling rainfall-induced landslides at a failure-prone catchment area in Enugu, Southeastern Nigeria using remote sensing data

Igwe

2015

Landslides

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Using remote sensing data and geographic information system (GIS) analytical techniques, we investigated instability at Iva Valley where there is an anomalous concentration of landslide scars. The area has a fairly rugged topography caused to a large extent by the headward erosion by the east-flowing Ekulu River. Mass wasting is more pronounced on the poorly consolidated sandstone (Ajali) formation which (as a major aquifer) serves as the source of the Ekulu River and its tributaries. At the lower portion of the formation and the uppermost part of shale (Mamu) formation (fractured in some places), inter-bedded thin mudstone layers provide the sandstones additional resistance to erosion, which however leads to steeper slopes and very deep and narrow stream channels. Digital elevation models show that the landforms are dominantly lowlands and lowhills with landslides concentrated on river tributaries where failures on the incised slopes create further instability. The overlying sandstone formation seems inherently unstable because of its semi-consolidated and friable nature. The fractures (orientated NE-SW) in the underlying shale formation and the occasional removal of lateral support by mining or road construction probably aggravate the instability. Additional stress on the unstable sandy mass resulting from increase in self-weight and pore pressure during rainfall readily induces failure, which then steepens the slopes and renders them vulnerable to more collapse behaviors that create clusters of scars. The results show good agreement with field observations and literature data indicating the importance of remote sensing analysis, ASTER, and SRTM imagery in geomorphologic interpretations.

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“…The thick Ajali Formation, which consists predominantly of fluviotidal sandstones, could represent the best potential reservoirs. These sandstones have fine-to-medium, sub-angular to rounded grains, and are moderately well-sorted quartz arenites, with high interparticle porosity (> 21%) and permeability values measured from surface outcrops, ranging from 7 to 55 darcy (Tijani and Nton 2009;Onyekuru et al 2015). These sandstones have also been affected by bioturbation which could enhance or damage reservoir quality (e.g.…”

Section: Reservoir Presence and Potentialmentioning

confidence: 99%

Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

Dim

Mode

Okwara

2018

J Petrol Explor Prod Technol

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Although several works have proved the existence of oil and gas in the Campanian to Maastrichtian strata of the Anambra Basin, it is still considered a frontier basin due to the challenges associated with interpretation of stratigraphy and structure arising from non-availability of subsurface data. This has led to poor understanding of the petroleum system and hindered exploration activity within the basin. This research paper aims to discuss the signatures of essential petroleum system elements, based on the study of high-quality outcrop examples. Detailed field studies reveal the presence of source, reservoir and seal rocks, and traps exposed within the four lithostratigraphic units outcropping in the basin, across the southeastern part of Nigeria. The shales of Enugu Formation, offer good source rocks. The shales, coals, coaly shales and sandstones with repeated occurrence of shale-silt-sand heteroliths of the Mamu Formation provide possible source and reservoir rocks. Thick extensive sandstones with clay laminae of the Ajali Formation offer potential reservoir that are partly compartmentalized. The shales with interstratified sandstone of the Nsukka Formation provide potential cap and overburden rocks. The presence of anastomosing fracture bands, extensional joints and faults, small-scale growth faults, and rollover anticlinal structures are good evidence of structural and stratigraphic configuration that could allow for possible migration, accumulation and entrapment of hydrocarbon. These recognized signatures of the key elements of a petroleum system and oil seeps encountered in the basin are an indication of the presence of an active petroleum system.

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Hydraulic, textural and geochemical characteristics of the Ajali Formation, Anambra Basin, Nigeria: implication for groundwater quality

Cited by 19 publications

References 34 publications

Geochemical Characteristics and Quality of Groundwater Around Okemesi Fold Belt, South Western Nigeria

Geochemical Characteristics and Quality of Groundwater Around Okemesi Fold Belt, South Western Nigeria

The study of the factors controlling rainfall-induced landslides at a failure-prone catchment area in Enugu, Southeastern Nigeria using remote sensing data

Signatures of key petroleum system elements: outcrop examples from the Anambra Basin, Southeastern Nigeria

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