Abstract
The Barberton Greenstone Belt (BGB) is a significant gold-rich geological domain, hosting over 350 gold occurrences with an estimated 342 tons of gold production. Prior studies have focused on large active mining sites like Fairview, New Consort, and Sheba. Our investigations encompass a broader exploration into the distribution and structural control of hydrothermal veins across historical mining regions and lower-grade gold occurrences. Our multifaceted research approach combines spatial analysis with field structural geology complemented by petrological and microstructural analyses. The objective is to understand the structural control of the gold-bearing large-scale event within the BGB. Our findings reveal four main clusters of gold occurrences and deposits within the Barberton Greenstone Belt distributed into high gold grade northern and lower gold grade southern parts.Two distinct tectonic events have been identified, forming hydrothermal veins. The first one, trending NW-SE and EW within the north and south belt, respectively, is related to the main deformation that structures the BGB, forming large-scale folding, thrusts and schistosity. The variation of trends is due to the arcuate geometry of the BGB. Both north and south, this event is related to the emplacement of the mineralised gold quartz veins responsible for gold economic grade. Different morphologies occur with, more frequently, vertical veins associated with horizontal ones and sometimes back-thrusting. The texture of the horizontal ones yields vertically elongated minerals (quartz, feldspars, tourmaline or carbonate). The second deformational event, attributed to NE-SW shortening, forms late barren quartz veins. This shortening event is also responsible for the development of a sub-vertical NW-SE schistosity prominently observed in the Malolotja Synform to the south of the belt.In summary, our research presents a comprehensive model of regional deformation and structural control of the gold mineralisation within the Barberton Greenstone Belt. An enigmatic NE-SW shortening event has been discovered, linked to a late hydrothermal event. These findings enhance our understanding of the geological evolution of the Barberton Greenstone Belt and its gold-bearing event.