Geochemistry and U-Pb zircon geochronology of the pegmatites in Ede area, southwestern Nigeria: A newly discovered oldest Pan African rock in southwestern Nigeria

2016 ◽  
Vol 115 ◽  
pp. 177-190 ◽  
Author(s):  
A. Adetunji ◽  
V.O. Olarewaju ◽  
O.O. Ocan ◽  
V.Y. Ganev ◽  
L. Macheva
2018 ◽  
Vol 7 (2) ◽  
pp. 166-187
Author(s):  
Abiola Oyebamiji ◽  
Adeniyi JohnPaul Adewumi ◽  
Tehseen Zafar ◽  
Adegbola Odebunmi ◽  
Philips Falae ◽  
...  

Abstract This research reviews the geology, petrogenesis, compositional trends and geochronology of the rare-metal pegmatite of southwestern Nigeria. The source of these pegmatites is still presently debated which have been explained as either product of highly fractionated molten material or anatexis of the local crust. However, published works of past authors have been compiled to give a detailed understanding of the formation of the mineral deposits. The basement complex of southwestern Nigeria comprises of Precambrian rocks of amphibolite, the hornblende gneiss and the granite gneisses which were formed as a result of the opening and closing of the ensialic basin with significant, extensive subduction during the Pan-African orogeny. The pegmatites in this region have shown internal zoning and a high degree of evolution from the border zone to the core zone during the crystallization and solidification of the felsic granite to pegmatite melt. The rare-metal pegmatites have distinct chemical compositions and mineralogy, containing quartz, biotite, muscovite, microcline, garnet with localized tourmaline, tantalite and columbite. These pegmatites vary significantly by their bulk-rock and mineral chemistry which indicates a more peraluminous attribute and enrichments of lithophile elements of Rb, Cs, Ta and Ba. Previous K/Ar isotopic ages (502.8±13.0 Ma and 514.5±13.2 Ma) suggest that the pegmatites are related to the post-collisional phase of intensive metasomatism. Adopted from previous studies, a five-stage conceptual model of evolution which is widely accepted have been proposed for the origin of the pegmatites.


2019 ◽  
Vol 150 ◽  
pp. 799-810 ◽  
Author(s):  
Bouchra Baidada ◽  
Moha Ikenne ◽  
Pierre Barbey ◽  
Abderrahmane Soulaimani ◽  
Brian Cousens ◽  
...  

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Olusola A. OlaOlorun ◽  
Segun Akinyemi ◽  
Ayomide J. Oluwaleye ◽  
Joseph Agbemuko

The geology, geochemistry of Iroko-granites have been studied and reported in this paper. The study area has been described as of Archaean –Early Proterozoic terrain underlain by migmatite-gneiss-quartzite complex with supracustal rocks. Large  number  of  granites which outcrops in Iroko-Ekiti represent a typical occurrence  of  granitoids sporadically  distributed  in  the  basement and  are known to  belong  to  the  Older Granite  suites,  which  are   attributable  to  the  Pan-African  Orogeny(750± 150Ma). The rocks occur, mostly as flat and low lying within sparse vegetation. Structures common on and around the outcrops include quartz vein, veinlets, pegmatite dykes which trend North-south, discrete exfoliated surfaces and xenoliths of older rocks. This study reveals that the granites belong to calc-alkalic suites, demonstrate metaluminous nature, and exhibit characteristics of I-type granites. The granite is a distinctive type in that it is relatively highly potassic, has high FeO/(FeO + MgO) ratio, and high average Zr (299.75ppm) concentration with other high field strength elements. The trace elements study implicates pronounced fractional crystallization during evolution of the granites and thus petrogenetically discriminates as Syn-collision provenance.


1984 ◽  
Vol 88 (1-2) ◽  
pp. 188-195 ◽  
Author(s):  
I. A. Tubosun ◽  
J. R. Lancelot ◽  
M. A. Rahaman ◽  
O. Ocan

2018 ◽  
Vol 40 (3) ◽  
pp. 288-298 ◽  
Author(s):  
Ademila O. ◽  
Akingboye A. S. ◽  
Ojamomi A. I.

Radiometric methods were used to investigate the radioactive properties of rocks in parts of southwestern Nigeria with a view to interpreting the geological structure and abundance of natural radioactive elements in the main type rocks. The airborne radiometric dataset of Ikole Sheet and ground radiometric data recorded from eight traverses in Akoko axis of the study area were processed. Results presented as maps and profiles displayed variations of high and low radioactive concentrations across the area. These maps showed moderate to very high concentrations and very low to low concentrations of the radioelements; uranium (4.5-13.0 ppm); (LLD-low limit of detection -3.0 ppm), Th (25.0-70.0 ppm); (8.5-16.0 ppm) and K (2.0-4.0 %); but the most often observed values are in the range 2.5-7.0 ppm, 22.0-30.0 ppm and 3.0-4.0% for U, Th, and K respectively. High concentrations imply that the rocks are crystalline, undeformed and are rich in feldspar and U-Th bearing minerals. While low radioactivity is attributed to varying geologic framework compositions; weathered materials or fluids formed as a result of intense metamorphism. The radiometric datasets proved valuable in delineating different rock types and serve as a complementary tool in identifying geochemical zoning of rocks in the area.ReferencesAjibade A.C. and Fitches W.R., 1988. The Nigerian Precambrian and the Pan-African Orogeny, Precambrian Geology of Nigeria, 45-53.Ajibade A.C., Woakes M. and Rahaman M.A., 1987.Proterozoic crustal development in Pan-African regime of Nigeria: In A. Croner (ed.) Proterozoic Lithospheric Evolution Geodynamics, 17, 259-231.Appleton J.D., Miles J.C.H., Green B.M.R, Larmour R., 2008. Pilot study of the application of Tellus airborne radiometric and soil geochemical data for radon mapping. Journal of Environmental Radioactivity, 99, 1687-1697.Arisekola T.M. and Ajenipa R.A., 2013. Geophysical data results preliminary application to uranium and thorium exploration. IAEA-CYTED-UNECE Workshop on UNFC-2009 at Santiago, Chile 9-12, July, 12.Bayowa O.G., Olorunfemi O.M., Akinluyi O.F. and Ademilua O.L., 2014.A Preliminary Approach to Groundwater Potential Appraisal of Ekiti State, Southwestern Nigeria. International Journal of Science and Technology (IJST), 4(3), 48-58.Bierwirth P.N., 1997. The use of airborne gamma-emission data for detecting soil properties.Proceedings of the Third International Airborne Remote Sensing Conference and Exhibition.Copenhagen, Denmark.Grasty R.L. and Multala J., 1991. A correlation technique for separating natural and man-made airborne gamma-ray spectra. In: Current Research, Part D, Geological Survey of Canada, 111-116.Grasty R.L., Minty B.R.S., 1995a. A guide to the technical specifications for airborne gamma ray surveys. Australian Geological Survey Organization, Record.Grasty R.L., Minty B.R.S., 1995b. The standardization of airborne gamma-ray surveys in Australia. Exploration Geophysics, 26, 276-283.IAEA, 1991. Airborne gamma ray spectrometer surveying, International Atomic Energy Agency, Technical Report Series, 323.IAEA, 2007.International Atomic Energy Agency. Safety Glossary, Terminology used in Nuclear Safety and Radiation Protection-2007 Edition.Jones H.A. and Hockey, 1964.The Geology of part of’ Southwestern Nigeria.Geological Survey, Nigeria bulletin, 31.Kearey P., Brooks M. and Hill I., 2002. An Introduction to Geophysical Exploration.3rd ed. Oxford: Blackwell Science, 262.Milsom J., 2003. Field Geophysics: The geological field guide series, John Milsom University College, London. Published by John Wiley and Sons Ltd. Third edition, 51-70.MontajTM Tutorial, 2004. Two - Dimensional frequency domain processing of potential field data.Nigeria Geological Survey Agency (NGSA), 2009. Geological map of Nigeria prepared by Nigeria Geological Survey Agency, 31, ShetimaMangono Crescent Utako District, Garki, Abuja, Nigeria.Omosanya K.O., Ariyo S.O., Kaigama U., Mosuro G.O., and Laniyan T.A., 2015. An outcrop evidence for polycyclic orogenies in the basement complex of Southwestern Nigeria. Journal of Geography and Geology, 7(3), 24-34.Oyawoye, M.O., 1972. The Basement Complex of Nigeria.In African Geology. T.F.J. Dessauvagie and A.J. Whiteman (Eds) Ibadan University Press, 67-99.Oyinloye A.O., 2011. Geology and Geotectonic Setting of the Basement Complex Rocks in Southwestern Nigeria: Implications on Provenance and Evolution. Earth and Environmental Sciences, 98-117. ISBN: 978-953-307-468-9.Rahaman M.A., 1981. Recent Advances in the Study of the Basement Complex of Nigeria.First Symposium on the Precambrian Geology of Nigeria, Summary.Rahaman M.A., Emofureta W.O. and Vachette M., 1983. The potassic-grades of the Igbeti area: Further evaluation of the polycyclic evolution of the Pan-African Belt in South-western Nigeria. Precambrian Resources, 22, 75-92.Woakes M., Rahaman M.A., Ajibade A.C., 1987. Some Metallogenetic Features of the Nigerian Basement. Journal of African Earth Sciences, 6(5), 655-664.


2019 ◽  
Vol 3 (2) ◽  
pp. 20-30
Author(s):  
C.C. Okpoli ◽  
D. Oludeyi

AbstractThe IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement complex was subjected to reduction to magnetic equator filtering, residual filtering, upward and downward continuation filtering, automatic gain control filtering, tilt angle derivative, second vertical derivative, analytical signal and Euler deconvolution. This reveals the geologic information such as structural trend. Based on the result of the total magnetic intensity map, reduction to equator map, analytical signal map and residual magnetic intensity map, it can be concluded that; The rocks in the study area have a trend of approximately northeast-southwest direction as seen on the upward continuation map. Most of the delineated lineaments found within the study area strike mostly in NNE-SSW, NE-SW and NW-SE with minor trend of E-W and ENE-WSW direction. Structural lineament orientation suggested that they were products of Pan-African orogeny (NE-SW, NW-SE and NNE-SSW trends) and pre-Pan-African orogeny (NNW-SSE and E-W trend). The interpretation of the aeromagnetic dataset gave an insight into the regional geology and structural trends of the area.


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