Geology, Petrography, Hydrogeology and Structural Analysis of Basawa and Its Environs, Part of Zaria Sheet 102 SW, Kaduna State, Northwestern Nigeria

Abstract

This study presents the geology, petrography, hydrogeology, structural characteristics, and economic significance of Basawa and its environs within Zaria Sheet 102 SW, Kaduna State, Northwestern Nigeria. Detailed geological mapping at a scale of 1:25,000, complemented by petrographic analysis of representative rock samples, was undertaken to characterize the lithological units and reconstruct the geological history of the area. The area is predominantly underlain by Precambrian Basement Complex rocks consisting mainly of gneiss and granitic intrusions, with minor occurrences of quartz veins, laterite, and alluvial deposits. Field observations reveal extensive structural features including joints, veins, dykes, foliations, and ptygmatic folds. Petrographic studies indicate that the gneiss is composed predominantly of quartz, plagioclase, orthoclase, microcline, biotite, and muscovite, whereas the granites consist mainly of quartz, feldspar, biotite, and muscovite. Structural analysis indicates dominant N–S to NE–SW trends consistent with regional Pan-African tectonism. Field relationships and petrographic evidence suggest that the gneiss constitutes the oldest lithological unit and was subsequently intruded by granitic bodies during the Pan-African orogeny. Although no economically significant metallic mineralization was identified, the abundance of granitic and gneissic rocks, lateritic materials, and alluvial deposits provides substantial potential for construction materials, groundwater development, and agricultural activities. The study contributes to the understanding of the geology and tectonic evolution of the Nigerian Basement Complex in the Zaria region.

Introduction

The study investigates the geology of the Basawa area in Zaria Sheet 102 SW, Kaduna State, Nigeria, which is part of the Nigerian Basement Complex within the Pan-African Mobile Belt. Although the Nigerian Basement Complex has been widely studied, detailed geological information on Basawa has remained limited. The research aims to characterize the area's lithology, petrography, structural features, and geological evolution through field mapping and laboratory analyses.

Basawa covers approximately 40 km² and was mapped at a scale of 1:25,000. The area is underlain by Precambrian crystalline basement rocks that have experienced multiple episodes of deformation, metamorphism, and magmatism. The Nigerian Basement Complex consists mainly of migmatites, gneisses, schists, quartzites, marbles, and intrusive igneous rocks such as granites, granodiorites, syenites, gabbros, and diorites. These rocks were affected by four major tectono-metamorphic events: the Liberian (2.8–2.7 Ga), Eburnean (2.0 Ga), Kibaran (1.1 Ga), and Pan-African (600 Ma) orogenies, with the Pan-African event producing widespread deformation, regional metamorphism, migmatization, granitization, and emplacement of granitoids.

Geological mapping was carried out using compass traversing, GPS, and structural measurements, while representative rock samples were analyzed petrographically using thin sections under a polarizing microscope. Structural analysis was performed using rose diagrams, and hydrogeological data were collected to prepare a hydrogeological map.

The study identified gneiss and granite as the dominant rock units, with minor occurrences of quartz veins, laterite, and alluvial deposits. Gneiss forms about 45% of the mapped area and approximately 75% of the exposed basement rocks, displaying well-developed foliation, gneissic banding, and evidence of exfoliation due to weathering. Petrographic analysis shows that the gneiss consists mainly of quartz, plagioclase, orthoclase, microcline, biotite, and muscovite, indicating medium- to high-grade metamorphism.

Granite occupies less than 20% of the study area and occurs as intrusive, dome-shaped or whaleback outcrops trending predominantly NW–SE. It is coarse- to medium-grained, with quartz, feldspar, biotite, and muscovite as the principal minerals, exhibiting hypidiomorphic granular textures typical of felsic intrusive rocks.

Structural features observed include joints, fractures, quartz veins, dykes, foliations, and ptygmatic folds, with dominant orientations ranging from N–S to NE–SW, reflecting the effects of Pan-African tectonic deformation.

Hydrogeologically, the area is drained by River Shika, which flows from northwest to southeast and provides water for domestic use and irrigation. Although crystalline basement rocks are generally impermeable, groundwater occurs within weathered and fractured zones of the gneiss. These shallow fractured and weathered zones possess better groundwater potential than deeper basement rocks, where fractures tend to close with depth.

Conclusion

Basawa and its environs are underlain predominantly by Precambrian basement rocks comprising gneiss and granitic intrusions. Petrographic and field evidence indicate that the gneiss represents the oldest rock unit, subsequently intruded by Pan-African granitoids. Structural features, including joints, veins, dykes, and foliations, display dominant N–S to NE–SW orientations consistent with regional tectonic trends. The area possesses considerable potential for groundwater development based on the well readings and depth analysis, thus, it can be established that the water table will be approximately met at depths of 3- 9meters during the rainy season (from east-west) relative to the topographical contour of the area for hand dug wells. This should aid and facilitate future water exploration studies. Economically, the area has prospect for construction materials and agricultural utilization. The study enhances understanding of the lithological, structural, and tectonic evolution of the Northwestern Nigerian Basement Complex.

References

[1] Adekoya, J. A. (1977) A note on jointing in the basement complex of the Ibadan area, Oyo State, Nigeria. J. Min. Geol., 14: 48-52. [2] Ajibade, A. C. (1976) Provisional classification and correlation of the schist belts in north western Nigeria. In Geology of Nigeria, pp. 85-90, ed. Kogbe , C.A., Elizabethan publishing Co., Ibadan. [3] Ajibade, A. C. (1980) Geotectonic evolution of the Zungeru Region, Nigeria. Unpublished Ph.D. Thesis, University of Wales, Aberystwyth. [4] Black R (1980) Precambrian of West Africa. Episodes 4:3–8 [5] Burke, K. C. and Dewey, J. F. (1972). Orogeny in Africa. In: African Geology, T.F.J. Dessauvagie and A.J. Whiteman (eds.), University of Ibadan Press, 583-608. [6] Danbatta, U. A. (1999) The Geotectonic evolution of the Kazaure schist belt in the Precambrian Basement of NW Nigeria. (A P.h.d dissertation, Ahmadu Bello University, Zaria.). [7] Falconer, J. D. (1911) The geology and geography of Northern Nigeria. Macmillan, London, 135pp [8] Gandu, A. H., Ojo, S. B. and Ajakaiye, D. E. (1986) A gravity study of the Precambrian rocks in the Malumfashi area of Kaduna State, Nigeria. Tectonophysics 126:181–194 [9] McCurry, P. (1971): The Geology of Degree sheet 21 Zaria. M.Sc Thesis (Unpublished, A.B.U. Zaria). Of Western Nigeria. West Africa Geo Science Review. 15, No.2 pp 145-158. [10] Muhammad, M. K., Haruna, A. I. and Maigari, A. S. (2022). Geology and petrography of the migmatites around Gubi and its environs, Bauchi, Northeastern Nigeria. Science Forum (Journal of Pure and Applied Sciences) 22: 123 – 130 [11] Obaje, N. G. (2009) Geology and Mineral Resources of Nigeria. Springer-Verlag, berlin Heidelberg. [12] Rahaman, M. A. (1988) Orogeny in Africa.Inpreceeding of the Africa Geology, University of Ibadan, Ed.By T. J. F. Dessoauvagie and A. J. Whiteman, pp 583-608. [13] Sa\'ad, A. S. and Baba, S. (2017). Geology and Petrographic Study of the Granitic Rocks of Kaltungo Inlier, Northeastern Nigeria. Journal of Applied Geology and Geophysics, 1 (1): 75-83.

Copyright

Copyright © 2026 Giade, I. U., Muhammad, M. K., Sa’ad, A. S., Boyoma, A. M., Kamale, H. I., Mohammed, Y. B., Usman, U. A., Giade, A. M.. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.