In the heart of Ghana’s Kumasi Basin, a recent study is shedding new light on the geological processes that have shaped one of the region’s most significant gold mines. The Edikan Mine, home to the Fobinso and Esuajah gold deposits, is nestled within the Asankrangwa Gold Belt of the Birimian Supergroup. A team of researchers, led by Emmanuel D. Sunkari from the Department of Geological Engineering at the University of Mines and Technology in Tarkwa, has been delving into the petrogenetic and geochemical characteristics of the granitoids in this area, with implications that could resonate throughout the global energy sector.
The study, published in the journal ‘Deep Underground Science and Engineering’ (which translates to ‘Deep Underground Science and Engineering’), employs a multi-methods approach, combining field studies, petrographic studies, and whole-rock geochemical analysis. The findings reveal a complex geological history, with granitoids intruding into the metasedimentary and metavolcanic rocks of the Birimian Supergroup during the Eburnean Orogeny.
Sunkari and his team discovered that the granitoids in the Edikan Mine are co-magmatic, meaning they originated from the same magma source. However, they exhibit distinct characteristics. The Fobinso samples are granodioritic, rich in plagioclase but low in K-feldspars, while the Esuajah samples are granitic, with a lower abundance of plagioclase and a higher percentage of K-feldspars. “This diversity in composition suggests a complex evolutionary history for these granitoids,” Sunkari explains.
The geochemical analysis revealed that the granitoids are enriched in large ion lithophile elements and light rare earth elements, indicating a mixing with crustal sources during their evolution. This suggests that the granitoids were formed in a syn-collisional setting, likely within a subduction zone. “This is a significant finding,” Sunkari notes, “as it provides insights into the tectonic processes that have shaped the region.”
The study also sheds light on the controls of orogenic gold mineralization in the Edikan Mine. The researchers found that gold mineralization is structurally and lithologically controlled, with shear zones, faulting, and veining playing crucial roles. Notably, the late-stage vein, V3, is characterized by a low vein angle and is mineralized, offering potential targets for future exploration.
The implications of this research extend beyond the Edikan Mine. Understanding the geodynamic settings and controls of orogenic gold mineralization can inform exploration strategies in similar geological settings worldwide. This could have significant commercial impacts for the energy sector, particularly in the context of the ongoing transition to renewable energy sources. Gold, a key component in many green technologies, is likely to remain in high demand.
As the world grapples with the challenges of climate change and the need for sustainable energy solutions, studies like this one are more important than ever. By unraveling the geological history of regions like the Kumasi Basin, researchers are not only advancing our scientific understanding but also paving the way for more sustainable and efficient resource extraction. In the words of Sunkari, “This research is a step towards a more sustainable future, one that balances our need for resources with the need to protect our planet.”