Multiple mineralization and fluid flow phases in the Central African Copperbelt: implications for the age dating of the ore-forming processes

Various models have been proposed for the ore-forming processes of sediment-hosted Cu-Co deposits in the Central African Copperbelt, ranging from a magmatic to syn-sedimentary, diagenetic and orogenic origin or a multiphase origin. The isotopic systems Re-Os and U-Pb have been applied with success to age date mineralizing processes in the Copperbelt. However, a problem in the age dating is the wide and sometimes even geologically unrealistic ages obtained by the Re-Os and U-Pb age dating of the ore minerals. The large range in mineralization ages reported for the Cu-Co ore deposits in the Copperbelt can be due to a variety of geological processes. They could reflect: 1) multiple mineralization phases as have been described for both the Congolese and Zambian part of the Copperbelt, 2) remobilization and recrystallization during subsequent fluid flow events, and 3) resetting of the isotopic system during later heating or fluid flow periods. The aim of this research is to: 1) characterize petrographically and geochemically the different mineralization, remobilization and recrystallization phases, 2) to propose objective criteria to distinguish these different phases and 3) to age date (U-Pb age dating) the different carbonate phases associated with both barren as well as mineralized phases.

Keywords:carbonate cements, Copperbelt, fluid flow evolution, sediment-hosted ores, U-Pb carbonate age dating

Disciplines:Geology not elsewhere classified, Geochemistry not elsewhere classified