Estimation of Crustal Thickness within the Sokoto Basin North-Western Nigeria Using Bouguer Gravity Anomaly Data

This research proposes an interpretation of the Bouguer’ gravity anomaly data of some parts of Sokoto basin for the estimation of crustal thickness. The study area is bounded between latitudes 1100′0″N and 1300′0″N, and longitudes 400′0″E and 600′0″E that covered Koko, Jega, B/Kebbi, Argungu, Lema, Bodinga, Tamgaza, Gunmi,Daki Takwas, Dange, Sokoto, Ilella, T/Mafara, Anka, Maru, Gusau, K/Namoda, and Sabon Birni within Sokoto, Kebbi and Zamfara state respectively. The established map of the study area was digitized in X, Y and Z format using excel software package and the digitized data were processed using Surfer version 13 software. The Moho and Conrad depths based on a relationship between Bouguer’ gravity anomaly determined crustal thickness were estimated as 35 to 37 km and 19 to 21 km, respectively. The crustal region has been categorized into: Crustal thinning zone that is the region with high gravity anomaly value due to its greater geothermal energy and also Crustal thickening zone which the region with low anomaly values due to its lower geothermal energy. Birnin kebbi, Jega, Sokoto were identified as the region of hydrocarbon potential with an estimate of 35 km thickness within the crustal region which is referred to as crustal thickening as a result of its low but sufficient geothermal energy to decompose organic matter within the region to form hydrocarbons.





References:
[1] Paul, I. and Bayode, E.N. “Watershed Characteristics and Their Implication for Hydrologic Response in Upper Sokoto Basin” Nigeria. Journal of Geography and Geology, Vol. 4(2), pp. 147 - 155, 2012.
[2] England, W.A. “The movement and entrapment of petroleum fluids in the subsurface”, J. Geol. Soc., 144, 327-347, 1987.
[3] Blanc P., Connan J. “Crude oils in reservoirs. The factors influencing their composition, in: Bordenave M.L”, Appli. Petro. Geochem. Paris, 149-174., 1993.
[4] Gotze H.J., Lahmeyer B., “Application of three-dimensional interactive modeling In gravity and magnetic”, Geophyss., 53, 1096-110, 1988:
[5] Abdelrahman E. M., Essa K. S., Abo-Ezz E. R., El-Araby T. M., Soliman K. S. “A Least-Squares Variance Analysis Method for Shape and Depth Estimation from Gravity Data”, J. Geophys. Eng., 3, 143–153, 2006.
[6] Abdelrahman E. M., Sharafeldin S. M., “A Least-Squares Minimization Approach to Shape Determination from Gravity Data” Geophys., 60: 589–590, 1995.
[7] Asfahani J., Tlas M., “Fair Function Minimization for Direct Interpretation of Residual Gravity Anomaly Profile due to Spheres and Cylinders” Pur. Appli. Geophys., 169, 157–165, 2012.
[8] Asfahani J., Tlas M. “Estimation of Gravity Parameters Related to Simple Geo-Metrical Structures by Developing an Approach Based on Deconvolution and Linear Optimization Techniques” Pur. Appl. geophys, 172, 2891–2899, 2015.
[9] Cordell L., Henderson R. G. “Iterative Three-Dimensional Solution of Gravity Anomaly Data using a Digital Computer”, Geophys, 33, 596–601, 1968.
[10] Chakravarthi V. “Automatic Gravity Optimization of 2.5 D Strike Listric Fault Sources with Analytically Defined Fault Planes and Depth-Dependent Density”, Geophys, vol. 76, no. 2, pp I21–I31, 2011.
[11] Essa K. “New Fast Least-Squares Algorithm for Estimating the Best-fitting Parameters due to Simple Geometric Structures from Gravity Anomalies”, J. Adv. Rese., vol. 5, no. 1, pp. 57–65, 2014.
[12] Dubey C. P., Gotze H.J., Schmidt S., Tiwari V. M. “A 3D model of the Wathlingen Salt Dome in the Northwest German Basin from Joint Modeling of Gravity, Gravity Gradient, and Curvature; Interpretation”, S. J., vol. 2, no. 4, pp. 103–115, 2014
[13] Essa K. “A simple formula for shape and depth determination from residual gravity anomalies”, Act. Geophy., vol. 55, no. 2, pp. 182–190.
[14] Nandi B. K., Shaw R. K., Agrawal B. N. P. “A Short Note on Identification of the Shape of Simple Causative Sources from Gravity Data”, Geophy. Prosp., 45, 513–520, 1997.
[15] Augie, A. I., Saleh, M. and Aku, M. O. and Bunawa, A.A. “Assessment of the Integrity of Goronyo Dam, Sokoto North-Western Nigeria using Geoelectromographic Technique,” Bayero J. Phys. Math. Sci., vol. 10, no. 1, pp. 231–243, 2019.
[16] Augie, A.I., M. Saleh, and A. A. Gado “Geophysical Investigation of Abnormal Seepages in Goronyo Dam Sokoto, North Western Nigeria Using Self-Potential Method”, World Academy of Science, Engineering and Technology, Int. J. Geotech., Geol. Eng., vol. 14, no. 3, 2020.
[17] A. I. Augie, O. Shariff and A. A. Sani, “Hydrogeophysical Investigation for Groundwater Potential in Kalgo Area, North Western Nigeria, Using Electrical Resistivity Method,” Sav. J. Basi. Appl. Sci., vol. 1, no. 2, pp. 180–187, 2019.
[18] Woolard, G.P.”Crustal Structure from Gravity and Seismic Measurements” J. Geophys. Res., 64: 1524-1544, 1959.
[19] Ram Babu, H.V. “Average Crustal Density of the Indian Lithosphere an Inference from Gravity Anomalies and Deep Seismic Soundings” J. Geodyn., 23: 1-4, 1997.
[20] Riad, S., Refai, E. and Ghalib. “Bouguer Anomalies and Estern Mediterranean” Technonophysics, 71 (1-4) 253-266, 1981.
[21] Funda, B. “Investigating Moho depth, Curie Point, and Heat Flow Variations of the Yazgat Batholith and its Surrounding Area, North Central Anatolia Turkey, using Gravity and Magnetic Anomalies” Turk. J. Ear. Sci., (2017) 26: 410 – 420, 2017.