Integrating gravity and magnetic field data to delineate structurally- Controlled gold mineralization in the Sefwi Belt

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Gravity and magnetic surveys have been used to delineate potential gold mineralization on the Sefwi belt of Ghana. The study area, which is intrusive dominated hosting pockets of small scale mining operations locally referred to as Galamsey, is without any scientific trend of gold mineralization. The study aims at mapping lithological units, structural setting and relating Galamsey sites to delineate potential zones of gold mineralization. Scintrex CG5 gravimeter and GEM’s Overhauser magnetometer were used for gravity and magnetic data acquisition respectively. The magnetic data were corrected and enhancing filters such as RTP, analytical signal and 1VD were applied using oasis montaj 7.1. Gravity data were also reduced to a common datum (geoid) using the oasis montaj software to produce a Bouguer anomaly map. Regional/residual separation technique produced a residual gravity map. The RTP and analytical signal filters from the magnetic data and residual gravity anomaly map from the gravity data helped in mapping belt type (Dixcove) Birimian granitoids and mafic intrusive unit, interpreted as gabbro. The first vertical derivative filter was useful in mapping NE/SW minor faults and crosscutting dykes largely concentrated in the belt type Birimian granitoids. All the three mapped Galamsey sites fell on a minor fault and are associated with the belt type granitoids which have been a lead in delineating potential zones of gold mineralization.
A thesis submitted to the Department of Geological Engineering College of Engineering in partial fulfillment of the requirements for the degree of Master of Science.