Significance of regolith mapping and its implication for gold exploration in northern Ghana: A case study at Tinga and Kunche

Abstract

The complex regolith in the savanna belts of northern Ghana is believed to be a major cause of the failure of gold exploration in the area. The present study highlights the integration of field regolith mapping, pitting and trenching in the classification of regolith and its significance to gold exploration at Tinga and Kunche in northern Ghana. These two areas are underlain by Birimian greenstones but have not seen any gold production apart from the reported gold occurrences known to be associated with the metavolcanic and metasedimentary rocks in the area. The importance of understanding the regolith, the landscape, and the sampling medium has not been seriously considered in past exploration programmes. The classification of the regolith regimes into ferruginous, relict, erosional and depositional regimes in the two study areas aided in determining the differences in the soil profiles, the source of the regolith materials and nature of weathering. For relict and erosional regimes, optimum depth of sampling was established to be between 0.2 and 0.4 m. However, for depositional regimes, because of the variable overburden thickness, the base of the transported materials was sampled. The pits and trenches dug also contributed in identifying the in-situ and transported regolith. The study shows that, in savanna areas of northern Ghana, relict regimes generally have preserved laterite profiles whereas the ferruginous, erosional and depositional regimes are associated with landscape modifications. © 2009 AAG/Geological Society of London.