Eoarchean to Neoproterozoic Detrital Zircons from the South of Meiganga Gold-Bearing Sediments (Adamawa, Cameroon): Their Closeness with Rocks of the Pan-African Cameroon Mobile Belt and Congo Craton

The core of detrital zircons from the southern Meiganga gold-bearing placers were analyzed by Laser Ablation Split Stream analytical techniques to determine their trace element abundances and U-Pb ages. The obtained data were used to characterize each grain, determine its formation condition, and try to trace the provenance. The Hf (5980 to 12,010 ppm), Y (27-1650 ppm), U (25-954 ppm), Th (8-674 ppm), Ti (2-256 ppm), Ta, Nb, and Sr (mainly <5 ppm), Th/U (0.06-2.35), Ti zircon temperature (617-1180 degrees C), n-ary sumation REE (total rare earth element) (98-1030 ppm), and Eu/Eu* (0.03 to <1.35) are predominant values for igneous crustal-derived zircons, with very few from mantle sources and of metamorphic origin. Crustal igneous zircons are mainly inherited grains crystallized in granitic magmas (with some charnockitic and tonalitic affinities) and a few from syenitic melts. Mantle zircons were crystallized in trace element depleted mantle source magmatic intrusion during crustal opening. Metamorphic zircons grown in sub-solidus solution in equilibrium with garnet syn-metamorphic zircons and in equilibrium with anatectic melts anatectic zircons during crustal tectono-metamorphic events. The U-Pb (3671 +/- 23-612 +/- 11 Ma) ages distinguish: Eoarchean to Neoproterozoic igneous zircons; Neoarchean to Mid Paleoproterozoic anatectic zircons; and Late Neoproterozoic syn-metamorphic grains. The Mesoarchean to Middle Paleoproterozoic igneous zircons are probably inherited from pyroxene-amphibole-bearing gneiss (TTGs composition) and amphibole-biotite gneiss, whose features are similar to those of the granites, granodiorites, TTG, and charnockites found in the Congo Craton, south Cameroon. The youngest igneous zircons could be grains eroded from Pan-African intrusion(s) found locally. Anatectic and syn-metamorphic zircons could have originated from amphibole-biotite gneiss underlying the zircon-gold bearing placers and from locally found migmatized rocks that are from the Cameroon mobile belt, which could be used as proxies for tracking gold.

Automated summary

Detrital zircons from the southern Meiganga gold-bearing placers were analyzed for trace element abundances and U-Pb ages, revealing that crustal-derived zircons mainly originated from granitic magmas, with few from mantle sources and of metamorphic origin. Age distinctions were made for igneous, anatectic, and syn-metamorphic zircons, providing insights into their formation conditions and provenance for tracking gold deposits.