Provenance and chemostratigraphy pof the Neoproterozoic West Congolian Group in the Democratic Republic of Congo
Lithogeochemical, chemostratigraphic, Rb–Sr and Sm–Nd isotope as well as U–Pb single zircon age data from the principal stratigraphic units of the West Congolian Group (West Congo Supergroup) in the West Congo Belt, Democratic Republic of Congo, presented in this reconnaissance study provide new insights into regional stratigraphic correlation and sediment provenance. The oldest unit (Sansikwa Subgroup) is a continental rift basin fill that culminated in a marine glacial diamictite (Lower Mixtite Formation), which is correlated with the global 750–720 Ma Sturtian glaciation. This is followed by a post-glacial, marine carbonate-dominated succession (Haut Shiloango Subgroup), a second diamictite unit (Upper Mixtite Formation) for which a syn-Marinoan (636 Ma) age is favoured, a post-glacial carbonate succession (Schisto-Calcaire Subgroup) and finally molasse sediments that experienced orogenic deformation at c. 566 Ma, as indicated by new 40Ar– 39Ar data. The youngest unit (Inkisi Group) is post-orogenic, derived from the West Congo Belt, and thus not part of the same supersequence. The proposed regional to global correlation of the various units is in line with progressively younger detrital zircon age spectra up-section. Overall, these age spectra indicate a Neoarchaean basement source (Congo Craton) and a Palaeoproterozoic source from the known Kimezian Supergroup to the west of the belt, which corresponds in age with the Eburnean of southern Africa. In addition, we identified a hitherto unknown late Mesoproterozoic source to the west of the belt, the age of which is comparable to the Espinhaço Supergroup of the Araçuai Belt in Brazil.
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