Aeromagnetic and Radiometric (Thorium) Data Interpretation for Kimberlite pipe(s) occurrence in Malumfashi North-Central Nigeria

Abstract

S. Fadeyi, C. Amos-Uhegbu and A. Adigun

Aeromagnetic and radiometric (thorium Th) data over the Malumfashi area in the Katsina State, North-Western Nigeria were analyzed to validate the occurrence of suspected volcanic pipes that are associated with kimberlite pipe(s) within the area. The thorium (Th) data were subjected to qualitative interpretation while the magnetic data were qualitatively and quantitatively processed. The volcanic pipes and other linear features were mapped using the Horizontal Gradient Method, and the general trends for the lineaments were determined to be in the Northeast-Southwest (NE-SW) and Northwest-Southeast (NW-SE) direction. The spectral analysis of the magnetic data was used to derive the depth of the magnetic sources. However, the deep magnetic sources were found to range from 0.08 to 0.45 km, while the depth for the shallow magnetic sources ranged from 0.05 to 0.09 km. The circular, semi-circular and elongate structures delineated were deduced to be associated with the kimberlite pipes and/or volcanic intrusions that are possible diamondiferous. The expressions occur as surface and near surface features.