Structural Interpretation of the Jos-Bukuru Younger Granite Ring Complexes Inferred from Landsat-TM Data

Abstract

A detailed study of the Landsat Thematic Mapper(Landsat-TM) image over Jos Plateau, Nigeria was carried out to identify linear geologic features that could be attributed to paleo-tectonic and/or neo-tectonic structures and to infer the influence of such structures on mineralization in the study area. The data was geo-referenced using the coordinates of the topographic map sheet of Naraguta. The application of directional edge enhancement techniques to band 5 of the Landsat-TM data using convolution models in ILWIS 3.2 academic software were to further enhance these linear features. Results of the structural analyses revealed several lineaments at the northwestern, central and southwestern parts of the study area. Trend analysis of the lineaments revealed structural trends in the NW-SE, NE-SW, N-S and E-W directions with the NW-SE and NE-SW been the dominant trends in the area. These trends correspond to the positions and directions of the paleo-tectonic fracture zones in the area. High lineament densities were also observed in areas where basement rocks outcrop or are close to the surface. The relationship between lineament densities and Younger granites occurrences in the study area is an indication of tectonic control probably associated with paleo-tectonic structures. This correlation is an indication that the emplacement of the Younger granite ring complexes may be associated with epeirogenic uplift. The epeirogenic uplift is believed to result from the intrusion of large masses of basic magmatic materials into the lower part of the continental crust in the area. The marked relationship between the Younger granites and the lineaments is believed to have controlled mineralization in the study area.