Lithological Deformation And Its Effect On Mineralization In Migori Greenstone Belt, Kenya

Abstract

Migori Greenstone Belt, located on the western part of Kenya is considered as one of the major gold fields in Kenya. It’s mineralization is believed to occur a long a system of veins. With the continuous extraction of minerals in this belt, exploration is currently evolving from surface based exploration to subsurface exploration. This necessitates a better understanding of the geophysical features in the subsurface which are likely to have a direct bearing on the distribution of minerals. The host lithosphere is suspected to be under compression forces given that it is located between the western and eastern branches of the east African rift system, which are divergent zones. The resultant lithological deformation is expected to directly affect the mineralization within the prospect. This study was conducted to map the structural deformations and their contribution to mineralization within the belt. 2D forward modeling of gravity data using Geosoft computer program was carried out along four profiles. This was done in an attempt to detect any lithological deformation and presence of anomalous structures by attaining the best fit between the observed gravity anomalies and the calculated responses. Forward modeling reveal a series of folding and dike like structures which probably occurred as a result of the deformation of the lithosphere of which Migori greenstone belt forms part. This must have occurred from Permian times to the Miocene. From the forward models, the mineral rich layer is brought closer to the surface at a depth of approximately between 0-500 m, majorly at the crests of the folds as a result of the lithological deformation. This explains the discontinuous shallow existence and outcropping of minerals along the belt.