Formation, evolution and economic potential of critical raw elements in Kenya rift volcanics

Abstract

The global demand for Critical Raw Elements (CRE) has increased owing to their role in clean energy solutions. This demand is expected to double or quadruple by 2050; thus, there is need for enhanced exploration, including new sites, to enable new ore discoveries. This study investigates the distribution of CREs in the volcanic rocks of the Kenya Rift, based on a review of various geochemical and petrological studies. Notable concentrations of chromium (Cr), vanadium (V), rubidium (Rb), zirconium (Zr), niobium (Nb), and barium (Ba) occur in the volcanic rocks of the Kenya rift system. The northern Kenya rift volcanic centers are identified for the economic exploration of Cr and Nb within mafic rocks. Additionally, V concentration up to twice the average concentration of the upper continental crust, can be considered for pilot studies to identify ore minerals. Critical elements such as Rb, Nb, and Zr enriched through fractional crystallization processes, and ongoing geothermal, tectonic and volcanic activities within Olkaria region in CKR are potential sites for future explorations. The northern Kenya rift basalts exhibit elevated concentrations of light rare earth elements (LREE), particularly La and Ce. In contrast, more evolved volcanic rocks, such as trachytes and rhyolites, demonstrate increased overall rare earth elements (REE) and yttrium concentrations, highlighting different magmatic processes along the Kenya rift. La, Ce, Nd, and Y occur at concentrations above 100 mg/kg in felsic volcanic rocks within the Kenya Rift. Siderophile critical elements such as Co, Ni, W, and platinum group metals (PGMs) are notably depleted, suggesting that the magmas underwent substantial differentiation processes that preferentially removed these elements from the melt. Similarly, the low levels of chalcophile critical elements (Sb, Ga, Ge, and Bi) indicate limited sulfide saturation and minimal hydrothermal alteration during volcanic activity. Generally, tectonic, magmatic, and surficial processes facilitate the formation and evolution of critical elements, and sedimentary basins within the Kenya rift represent potential sites for the accumulation of these essential elements. These findings provide direction for resource exploration and evaluation within the Kenya rift system.