Intermediate –basic intrusive and volcanic form structurally-controlled topographic features in Ishiagu area of Afikpo basin, southern Benue trough of Nigeria. Petrogenesis of the rocks was studied using major, trace and ree. Interpretation of data confirm the division of the rocks into three groups (Syenodiorite, basalt and pyroclastics). Basalt occurs along horizontal contact of syenodiorite with overlying pyroclastics .These rocks intruded the Albian sediment. Petrogenetic modeling suggests that the rocks are not cogenetic and represent various stages of crystallization from three different and genetically unrelated magma. The extent of variation can be related to (i) magmatism originating from mantle, (ii), crystal fractionation, (iii), magma mixing and /or mingling, (iv), varying degree of partial melt, (v ), assimilation and contamination, (vi),batch melting ,(vii) hydrothermal alteration. These processes could operate alone or simultaneously. They will be evaluated on the basis of observations that have been made on the igneous suite. Different mechanisms will be considered particularly i, ii, iii, iv.vi,
