A palaeomagnetic study of Cainozoic basalts from Northern Nigeria

Abstract

Palaeomagnetic results are presented for 95 specimens from 10 sites from the Jos Plateau Cainozoic basalts in the Northern Nigeria volcanic province. Available K–Ar age determinations from this area suggest that the rocks formed during the Pleistocene. After alternating field demagnetization, the mean direction of the natural remanent magnetization is D= 341.7°, I=–8.7° with α95= 4.2°. This yields a virtual geomagnetic pole position of 67.0°S, 63.0°E. An estimated average palaeomagnetic latitude of about 4.4°S for the area of study when compared with the present geographic latitude of about 9.5°N, implies a latitudinal northward drift of about 14° for the African plate since the time of formation of the rocks. This is incompatible with current models for plate motions and most likely represents the effects of conditional local tectonic movements or departures of the geomagnetic field from an axial dipole configuration. Copyright © 1991, Wiley Blackwell. All rights reserved