A review of the current state of knowledge on gold mineralization in Mali, Western Africa

Abstract

This paper comprehensively analyses the geology and geochemistry of the relatively understudied gold resources in Mali. It also examines the potential of stable isotopes in enhancing gold prospecting within the Birimian terrane. The key characteristics of gold deposits in Mali include sulfides in shear zones, ankerite veins, tourmalinized sandstone, hydrothermal breccias, and gold-bearing quartz veins near diorite. Gold-bearing fluids in Mali show a strong affinity for CO2, similar to those found in Eburnean orogenic gold deposits. Isotope research suggests varied sources, including crustal, marine evaporite, magmatic, and metamorphic origins. Notably, fluid data from Morila and type 3 Kalana deposits reveal some disparities. Surprisingly, barren quartz veins exhibit δ18O values similar to mineralized veins. In contrast, the δ13C values differ significantly between mineralized and barren samples, with the latter primarily deriving carbon from sedimentary rocks. Additionally, the δ34S sulfur isotope data from Mali align with syngenetic-diagenetic pyrites, contrasting with Ghana’s Ashanti belt. The varied δ11B values for tourmaline indicate shifts in fluid sources. This study underscores the importance of baseline alteration studies and suggests that variations in δ¹³C values of carbonates could be a valuable method for identifying gold mineralization in Mali.

Keywords

• Gold exploration
• Mali
• stable isotope
• geochemistry
• review