PETROLOGICAL AND STRUCTURAL EVOLUTION OF BASEMENT ROCKS AROUND GUGA, KATSINA STATE, NORTHWESTERN NIGERIA

Abstract

Lithological characterization and structural assessments of basement rocks around Guga, Katsina State was carried out to understand their geologic evolution and deformational history better. Field and petrographic studies were utilized in characterizing macrostructural, textural, and mineralogical components. Migmatite, banded and augen gneisses, schist, quartzite, and granite constitute the major lithologic units in the study area. Migmatite and the closely related banded gneiss are recognized as igneous-derived metamorphic rocks of Eburnean to early Pan African. In contrast, the augen gneisses are metamorphosed analogues of earlier banded gneiss that were intensely deformed within a ductile shear zone during the middle stages of the Pan African. Similarly, the schist and interbedded quartzite were emplaced during this period, subsequently forming part of the Malumfashi supracrustal cover, related to simple ensialic graben-like structural development. The granitic intrusions represent the youngest rock units in the mapped area, resulting from the magmatic activity of the Pan-African orogeny.  Structural analysis suggests the mapped area was affected by two-phase deformation events (D1 and D2). The D1 deformation represents a regional, fabric-forming compressional event, while D2 is a localized deformational event associated with the development of a local shear zone linked to the Kalangai fault system (KFS).