Journal of The School of Marine Science and Technology,Vol.8 No.3
GOLD POTENTIAL OF THE ASHANTI BELT OF GHANA
Jerry S.Kuma, Yong Ui Kim, Daniel Boamah and Izumi Sakamoto
Abstract
Traditionally, the principal gold belts of Ghana have been largely grouped with the greenstone/volcanic belts with which they are associated. The Ashanti belt is one of the main belts associated with gold mineralization in Ghana and it is over 200 km in length and is characterized by a large number of gold deposits, including both abandoned and active mines like AngloGold Ashanti, Golden Star Resources at Prestea and Bogoso and Goldfields at Tarkwa and Damang. The Ashanti belt is made up of two main rock systems that are associated with the main gold occurrences in the form of quartz vein and disseminated type gold deposits; gold bearing quartz pebble conglomerates; alluvial deposits and oxide deposits derived from the primary occurrences.
The Ashanti-type of gold occurrence usually features complicated quartz vein systems commonly associated with extensive disseminated sulphides.The vein systems almost invariably appear to be related to regional NNE to NE trending regional structures (tectonic corridors), which are typically concentrated along the margins of various Birimian ‘greenstone’belts and adjacent metasedimentary basins. Although the N to NE trending ‘structural corridors’may be of prime importance, there is increasing evidence to indicate that other structures may have played very important roles as well, and some may be responsible for the development of the really large vein deposits.
The recent exploration activities in the Ashanti belt have confirmed a great variety of settings in which gold can be concentrated in commercial quantities. Epigenetic vein systems and related disseminated sulphide gold deposits will continue to be a major focus for future exploration. Structural controls for these vein systems appear to be the most important feature from the explorationist’s viewpoint but it is now believed that potential source rocks with anomalous background levels of gold may also be important. The geochemistry of depositional sites can be important in determining whether gold will be sufficiently concentrated to be of economic interest. The stockworks in the Damang area near Tarkwa have also opened up other opportunities to explore stockwork types of gold mineralization in other parts of the Ashanti belt. The much improved gold prices could eventually lead to renewed interest in the considerable underground exploration which will also likely take place in the central and northern portions of the Ashanti belt where Tarkwaian metasediments are widespread and some gold indications are known.