Joint Studies In The Western Part Of Ikom-Mamfe Basin, Lower Benue Trough, Nigeria

Abstract

The Ikom-Mamfe basin, also called the Mamfe embayment, is a bifurcation of the Benue trough in southeastern Nigeria and southwestern Cameroun. The basin is about 130km long, 60km wide basin and is filled with about 4km thick sedimentary rocks. Deformational events led to gentle folding of rocks in the basin and emplacement of magmatic rocks. Systematic and detailed field studies were carried out in eight (8) locations within the study area, in which the orientations of 1437 joints and 102 veins were acquired. Two sets of orthogonal joints observed in the study exhibited symmetry with respect to the directions of the fold axes and were dominated by high-angle dips averaging about 80^o. This implies a syntectonic origin of these structures also during their propagation, the maximum principal stress directions (σ₁) were orientated in two different directions NW- SE and NNE-SSW for D_I and D₂ respectively. The relative strength of deformation during D_I was greater than D₂ and it was also unfolded that the ‘ac’ extension joints trending NW- SE and NNE-SSW hosted relatively thicker veins in both D_I and D₂. These joints served as better conduits for mineralizing fluids and also most suitable directions for future prospecting.