Updating the geology of the Volta river and Keta Basin of Ghana using remote sensing and focussed field mapping

The British Geological Survey (BGS) worked with Fugro Airborne Surveys and the Ghana Geological Survey Department on a European Union funded project (8 AGP GH 027/13) to update the geology and topography maps and undertake prospectivity modelling for an area covering approximately 100,000km2. The focus of the BGS input was to update the geological knowledge of the Volta and Keta Basins and the resulting maps are being used for a variety of applications including encouraging inward investment by exploration companies who use them as a baseline for choosing prospective zones. Existing published materials were loaded into a GIS along with newly processed satellite and airborne imagery for heads-up geological interpretation. The satellite remote sensing data included 92 Radarsat fine beam images, 24 Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) scenes, and a 50m DTM derived from SRTM. The BGS interpretations and revised geological model were checked and updated over two field seasons using mobile GIS field mapping techniques. 96 topography and geology maps were produced by BGS at 1:100,000 scale. The combination of remote sensing and focussed field mapping enabled the geology of a large area to be mapped objectively within a short timescale. A substantial upgrade to the geological knowledge base of the area is now available to investors and researchers alike. This paper outlines the remote sensing methodology, along with a brief description of those geological results which are not commercial-in-confidence.