Geology and Mineralization
The Kyereboso No. 2 and No. 3 and Meduma concessions straddle the northwest contact of the Ashanti Volcanic Belt and are underlain by alternating bands of Tarkwaian and Birimian sedimentary rocks separated by narrow belts of Birimian volcanic rocks or dolerite intrusions. A belt-type felsic pluton intrudes the Birimian sedimentary and volcanic rocks in the northern portion of the concessions. Work by Pelangio and reconnaissance mapping by Randgold indicate the presence of discontinuous graphitic shear zones in the western parts of the Kyereboso No. 2 concession. This geological and structural setting is similar to that at Anglogold Ashanti's Obuasi Mine.
At the Obuasi Mine, gold mineralization is associated with major northeast striking, five to forty metre wide graphite-chlorite-sericite fault zones and commonly associated with pervasive silica, carbonate and sulphide hydrothermal alteration. On a broad regional scale, left stepping flexures along northeast striking fault zones are important for the localization of gold mineralization. Two distinct types of gold mineralization are recognized: quartz vein free-milling gold lodes and sulphide-rich (arsenopyrite) disseminated refractory gold lodes which are interpreted to form alteration haloes around the quartz vein lodes.