Structural architecture of the Middle Niger Basin, Nigeria based on aeromagnetic data: An example of a non-volcanic basin

Abstract

The Middle Niger Basin is located within the west-central half of Nigeria, as a NW-SE trending Campano-Maastrichtian depo-centre which extends from the southern end of the Sokoto Basin west of Kainji reservoir southwestwards to the convergence of the Benue and Niger Rivers at Lokoja. The aeromagnetic anomaly data of the Middle Niger Basin was interpreted to characterize the structural architecture and depth to the magnetic basement of the basin. This is to expand the current knowledge of the region. The analysis of the data has been facilitated by the application of derivative and source parameter imaging techniques. The results from the application of total gradient to the aeromagnetic data provided here signify a rift origin of the basin and NW-SE trending fault systems in the surrounding basement complex terrain. The absence of magnetic highs on the first vertical derivative of the reduced-to-pole aeromagnetic data reveals lack of volcanic rocks within the sedimentary layers of the basin. Additionally, the consistent NW-SE trending source parameter imaging depth solutions within the basin confirm the internal geometry and NW-SE orientation of the basin with sediments not more than 1100 m thick.

The Middle Niger Basin in Nigeria Has a Rift Origin, as Revealed by the Inversion and Modeling of Gravity and Magnetic Data

“…This interpretation is corroborated by the low-frequency characteristics of these anomalies, indicative of the presence of igneous intrusive features within the basin's basement. Studies conducted by Kogbe et al (1983), Salawu et al (2020Salawu et al ( , 2021 provided additional supporting evidence for this interpretation, collectively confirming the distinctive nature of the Middle Niger Basin as an extensional sedimentary basin. This uniqueness is attributed to its formation within an extensional tectonic setting, where basement faults are rejuvenated because of the ascent of plutons.…”

“…The joint magnetic and gravity modeling of profile B-Bʹ was constraint by density values of sedimentary and volcanic rocks in adjacent Benue Trough (Table 1) as reported by Ajayi and Ajakaiye (1986). Furthermore, the density values from Stanton et al (2021) were used for the upper crust, lower crust, and the mantle in profile B-Bʹ (Table 1) while we used top basement depth values ranging from 1 to 2 km in the simulation (Ojo, 1990;Salawu et al, 2020Salawu et al, , 2021. According to Bouzid et al (2008), Brahimi et al (2018) and Deramchi (2016), 20 km may be employed to estimate top of the lower crust in the Trans-Saharan Belt.…”

Aeromagnetic and digital elevation model constraints on the structural framework of southern margin of the Middle Niger Basin, Nigeria

“…In justification, recent aeromagnetic investigation of the Middle Niger Basin by Ref. 18 revealed that the basin is characterized by the absence of volcanic rocks. There is a regional trend (long wavelength) increase in the field northerly part of the RTP map.…”

“…The basin has an average sedimentary pile of approximately 950 m from recent aeromagnetic results of Refs. 1,18 with two geographic subdivisions; the northern and southern segments. Four stratigraphic horizons in the northern part have been identified, which they include; the basal Bida Formation (conglomerate, sandstone) and Sakpe Ironstone of Campanian age and Enagi Formation (sandstone, siltstone, claystone) and Batati Ironstone of Maastrichtian age [19][20][21] .…”

Basement depth re-valuation of anomalous magnetic bodies in the lower and middle Benue trough using Euler deconvolution and spectral inversion techniques

“…Towards the Southern and Northeastern part of the RTP map, the area is characterized by a relatively low magnetic intensity `value from -467.2 nT to -865.2 nT marked with blue colour. The closed contours represent high magnetic signatures linked to shallow structures such as contacts, fractures and intrusive bodies [41]. Reynold et al [40] and Opara [31] have associated the series of low magnetic closures with linear trends, which initiate shear/fault zones.…”