LA-ICP-MS element analysis of Cu–Co sulfides from the Central African Copperbelt: implications for the mobility and redistribution of metals

This study involves the geochemical analysis of sulfides from the Tenke Fungurume mining district (TFMD), Kamoto and Luiswishi deposits in the Congolese Copperbelt and the Nkana deposit in the Zambian Copperbelt. The objective is to better understand the ore-forming processes and the distribution of metals within these deposits. The trace element contents of carrollite and chalcopyrite suggest that ore fluids varied in metal contents across different locations within the Central African Copperbelt (CACB). This variability likely reflects localized ore fluid sources and separated mineralizing systems for each deposit, rather than a single, homogenized basin-wide fluid reservoir. Carrollite displays a trend of decreasing Co/Cu ratios from the central part of the Congolese Copperbelt, i.e. from Luiswishi through TFMD to Kamoto in the western part. Within each deposit, the trace element content of carrollite exhibits minimal variations across different paragenetic phases, indicating the re-equilibration of the diagenetic sulfides during the subsequent mineralization phases. This is further corroborated by the trace element composition of chalcopyrite, which exhibits consistent patterns across the main mineralization phases. However, at TFMD, chalcopyrite from the syn-folding vein differs notably from that in the pre-folding and post-folding veins, suggesting the presence of separate mineralizing phases within a single deposit. The exceptionally high germanium (Ge) content (av. = 273 ppm, up to 772 ppm) in chalcopyrite from the post-folding stage at TFMD may be linked to a significant post-orogenic mineralization event that led to the formation of the Cu-Zn-Pb (Ge, Ag) Kipushi deposit in the Congolese Copperbelt.