Structural evolution of precambrian basement rocks of Jebba area, s.w. Nigeria

Okonkwo, C. T.

doi:10.4314/gjgs.v6i2.18764

Cited by 8 publications

(12 citation statements)

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“…The very strong planar fabric is defined by the alignment of muscovite and quartz ribbons as well as by opaque mineral (magnetite) strewn along the foliation. The granitic gneiss is also locally marked by also a very strong linear fabric-a stretching lineation-defined by quartz and feldspar grains plunging gently to the NNW [13]. Locally, the granitic gneiss contains very thin, elongate slivers (xenoliths) of dark, schistose material believed to be derived from the preexisting country rock.…”

Section: Petrography Of the Jebba Leucocratic Granitic Gneissmentioning

confidence: 99%

“…The polyphasal nature of the deformation and metamorphism of the Nigerian basement complex rocks has been recognized and documented by several workers e.g. [7,[10][11][12][13]. Several orthogneisses of Paleoproterozoic age have been documented from some parts of southwestern Nigeria including Ibadan granitic gneiss-Rb/Sr isochron age of 2206 ± 70 Ma [4], Ile-Ife grey gneiss-U-Pb age of 2.3 Ga [9], Igbeti augen gneiss-Rb/Sr isochron age of 1.9 Ga [14], Kabba granodioritic gneiss-U-Pb age of 2103 ± 8 Ma [2].…”

Section: Introductionmentioning

confidence: 99%

“…facies [13]. These rocks have been intruded by largely undeformed granitic rocks of probable Neo-Proterozoic age emplaced during the Pan-African orogeny.…”

Section: Introductionmentioning

confidence: 99%

“…These involved foliation development, several generations of folding as well as ductile shearing and brittle faulting [13]. The boundary between the granitic gneiss and the metagreywacke is a tectonic one defining a ductile thrust with a top to the southeast transport direction [13].…”

Section: Introductionmentioning

confidence: 99%

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U-Pb Geochronology of the Jebba Granitic Gneiss and Its Implications for the Paleoproterozoic Evolution of Jebba Area, Southwestern Nigeria

Okonkwo¹,

Ganev²

2012

IJG

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Jebba area southwestern Nigeria forms part of the Nigerian basement complex which lies in the Neoproterozoic PanAfrican mobile belt. It is underlain by several lithological units among which is a polydeformed granitic gneiss. This rock has been dated by LA-ICP-MS yielding a concordant U-Pb zircon age of 2207 ± 20 Ma indicating the crystallization age of the granite protolith. This early Rhyacian age and its affinity with within-plate granites indicates emplacement during crustal extension and rifting preceding the main phase of the Eburnean orogeny. The strong, early, shear fabric, S 1 , in the rock is interpreted to be also of Paleoproterozoic age i.e. imprinted during the Eburnean orogeny. The Jebba granitic gneiss is thus correlatable with the widely abundant Paleoproterozoic granitic magmatism now represented by many orthogneisses and documented in other parts of southwestern Nigeria, the West African craton, the Borborema Province, the Gurupi Belt, Sao Luis craton and Sao Francisco craton in Brazil.

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Section: Petrography Of the Jebba Leucocratic Granitic Gneissmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…facies [13]. These rocks have been intruded by largely undeformed granitic rocks of probable Neo-Proterozoic age emplaced during the Pan-African orogeny.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

U-Pb Geochronology of the Jebba Granitic Gneiss and Its Implications for the Paleoproterozoic Evolution of Jebba Area, Southwestern Nigeria

Okonkwo¹,

Ganev²

2012

IJG

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“…The researcher also observes that joints ranging from minor to major ones are found in all the rock types, some of which are filled with quartz, feldspars or a combination of both which lie generally in the NE-SW direction, while the south western basement complex of Nigeria has been affected by two phases of deformation namely D1, D2, the first phase (D1) produced tight to isoclinals folds while the second phase (D2) is characterized by more open folds of variable style and large vertical NNE-SSW trending fault. Other scholar gives evidence that within the basement complex, tectonic deformation has completely destroyed primary structures except in a few places where they survived deformation [24].…”

Section: Location and Geologic Settingmentioning

confidence: 99%

High Resolution Magnetic Field Signatures Over Akure and Its Environs, Southwestern Nigeria

Ikeoha¹

2019

Earth sci. Malays.

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Aeromagnetic data over Akure, Southwestern Nigeria was quantitatively and qualitatively analyzed to unravel subsurface magnetic anomalies. The analyses made on the IGRF corrected aeromagnetic data acquired was used to estimate depth to anomalous sources using 2-D power spectrum, werner deconvolution and 3-D Euler deconvolution. We gridded and sampled the aeromagnetic dataset; while the spectral analysis transforms the spatial data into frequency domain and provides a relationship between radially average spectrum of the magnetic anomalies and depths to the respective sources. Werner and Euler estimate and examines the shape, type of magnetic field within a window and calculate 3-D source locations based on its structural index. The characteristic nature of the magnetic anomalies as expressed by the profiles that is indicative of the different rock types (charnokite, porphyritic granite, grey gneiss, migmatite). Qualitative interpretation results revealed the following ranges for reduction to equator, upward and downward continuation, analytical signal, vertical derivative as;-418.29nT to 532.35nT,-96.7T to 175.4nT,-544.53nT to 597.70nT,-0.0nT to 2.199nT,-0.1nT to 0.1nT; while the quantitative interpretation results revealed-power spectrum, werner deconvolution and euler deconvolution as: 3.0m to 11.0m, 20.6m to 650m, 166.29m to-323.05m respectively. Location, source and depth of magnetic anomaly have been unraveled.

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Landslide in parts of southwestern Nigeria

Bamisaiye

2019

SN Appl. Sci.

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Landslides represent "structural failures" with great risk to the environment, and this makes the study of the mechanism of formation of landslides very important. Most parts of the Okemesi ridge are inherently dangerous areas, at high risk of sliding. This research is one of the first detailed geological investigations of landslides in this area. This research evaluates the importance of the lithological, structural and geomorphological factors to landslide activities in parts of southwestern Nigeria with the aim of designing a susceptibility map which is intended to serve as an early warning and mitigation measures. The result revealed that the latest landslide was caused by the release of intensely fractured rocks along adjacent blocks of a fault plane, and prevalent tectonic stress condition set the stage for the landslide, while slope instability in conjunction with prolonged high-intensity rainfall triggered the movement. The most susceptible area of landslide is within the slope angles of between 45° and 75° with an elevation of between 514 and 666 m. The research further revealed that the landslide occurred about 500 m to the road. The landslide-prone location is within the 0-200 m from the hill; hence, human settlements and activities should be sited at least 500 m away from the hill.

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Structural evolution of precambrian basement rocks of Jebba area, s.w. Nigeria

Cited by 8 publications

References 0 publications

U-Pb Geochronology of the Jebba Granitic Gneiss and Its Implications for the Paleoproterozoic Evolution of Jebba Area, Southwestern Nigeria

U-Pb Geochronology of the Jebba Granitic Gneiss and Its Implications for the Paleoproterozoic Evolution of Jebba Area, Southwestern Nigeria

High Resolution Magnetic Field Signatures Over Akure and Its Environs, Southwestern Nigeria

Landslide in parts of southwestern Nigeria

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