Integrated interpretation of airborne geophysical data and satellite image for geological mapping of the Kalenge Area, Biharamulo District, North-Western Tanzania

Integrated interpretation of aero geophysical and satellite image data were used for geological mapping of the Kalenge area, Biharamulo District. North-Western Tanzania. The data used in this study were acquired from high-resolution airborne geophysical survey (magnetic, radiometric and EM) and satellite image data. Five geological units have been mapped: Nyanzian granite-greenstone belt, the Karagwe-Ankolean super group, the Bukohan group, the younger sediments of the ‘Uha group and superficial deposits including black cotton soil (mbuga), chocolate brown soils and laterites. Two major dyke swarms of probable Proterozoic age (1350 Ma) have been characterized using airborne magnetic data. The dyke swarms are NE-SW and NNE-SSW. The quantitative interpretations of the dyke swarms deduced that the dip angles vary in the order of 16°- 50° dipping towards NW and depths from the surface to the top of the dykes range from 10 m - 500 m. The decrease in depths from 500 in to 10 m is attributed to the increase of the overburden thickness towards the SW of the study area. The geological boundaries of the three tectonic domains of the Nyanzian Super group, the Karagwe-Ankolean super group and the Bukoban groups have been elucidated. An inferred fault boundary is interpreted to fall along the Mwiruzi River valley and tend to mark the contact between the Karagwe-Ankolean super group and the Bukoban group. The interpreted boundary between the Bukohan group and the Nyanzian Super group is coincident with the prominent NE-SW dyke swarms and represents the contact between shale, sandstone and orthoquartzite of Bukohan origin and metavolcanics and granite of Nyanzian. The results of this study has demonstrated the effectiveness of using digital integration based on satellite images and aero geophysical data in systematic surface and subsurface geological mapping in developing countries such as Tanzania.