Timing and genesis of gold mineralization in the Kibaran Metallogenic Province, D.R. Congo: Constraints from zircon UPb geochronology, trace element chemistry, and LuHf isotopes

Abstract

The Kibaran Metallogenic Province represents a world-class metallogenic system, hosting a diverse array of metal deposits, including significant gold mineralization. Despite its economic importance, the genesis and metallogenic evolution of gold mineralization in this region remain poorly understood. This knowledge gap is primarily due to the absence of comprehensive studies that can provide a coherent genetic model for its formation, making it challenging to contextualize the Kibaran gold deposits within the broader framework of global gold occurrences. In this study, we present new UPb geochronology, trace element chemistry, and LuHf isotopic data from zircons extracted from mafic and intermediate-felsic, and sedimentary rocks to elucidate the geodynamic processes and emplacement mechanisms of gold mineralization in the metallogenic province. Our zircon UPb data reveal two major episodes of gold mineralization: (a) an early Mesoproterozoic event ~1415 Ma associated with the end of Eburnean orogeny, marked by a rift-related magmatic system and dolerite dykes emplacement at Misisi gold field, and (b) a mid-Paleozoic event (~468-333 Ma) linked to the end of Pan-African orogeny, characterized by sedimentation at Misisi and diorite and feldspar porphyry intrusions at Twangiza. LuHf isotopic signatures indicate that both magmatic episodes resulted from partial melting of the older Congo-Ruzizian basement, with juvenile crustal input. Zircon trace element compositions suggest that gold mineralization was generated under high-temperature, oxidizing fluid conditions, with magma migrating from the lower to the upper crust, where it interacted with reduced fluids from carbonaceous country rocks, facilitating gold deposition. These findings suggest that the gold mineralization events in the Kibaran Metallogenic Province coincided with failed rift systems during the breakup of the Columbia and Gondwana supercontinents. This study provides new insights into the temporal relationships between supercontinent cycles and gold mineralization events in the Democratic Republic of Congo.