STRUCTURAL SETTING, GEOLOGY AND THE GOLD MINERALIZATION OF THE TWANGIZA GOLD DEPOSIT, SOUTH KIVU, EASTERN DR-CONGO

The Twangiza deposit is located in the middle part of the Neoproterozoic Itombwe synclinorium, which forms a N-S domain from Luemba in the Fizi territory of South-Kivu province to Sake in the North-Kivu province. Gold mineralization in the Twangiza deposit is structurally controlled by a double plunging N-S anticline related to the Pan African orogeny at about 560 Ma. Two different gold mineralization styles are encountered in the Twangiza deposit: (i) gold mineralization in felsic intrusives characterized by pervasive hydrothermal alteration at the Twangiza north deposit (the northern extension) and (ii) in both sedimentary rocks and the felsic intrusive rocks in the Twangiza main deposit. Sulphides (pyrite and arsenopyrite) are relatively common at the Twangiza deposit. In the felsic sills, sulphides form disseminations and irregular intergrowths of pyrite and arsenopyrite in quartz and carbonate. In the sedimentary rocks disseminated sulphides are fine grained.