Trace Element and U–Pb Core Age for Zircons from Western Meiganga Gold Placer, Cameroon: Their Genesis and Archean-Proterozoic Sources

Abstract

Trace element concentrations and U-Pb ages were obtained using Laser Ablation Split Stream Method from the core of 115 zircon grains from the western Meiganga gold placer deposit. The data was used to characterize zircon, to understand the history of crystallization and to locate source rocks within the local and regional geological settings. Zircon trace element geochemistry was used to distinguish between magmatic and metamorphic affinity. The magmatic zircons have characteristics compatible with their probable origin from granitoid, syenite, tonalite, charnockite and mafic to ultramafic rocks. The metamorphic zircons composition is compatible with growth from anatectic melts and by sub-solidus crystallization in equilibrium with garnet. The zircon ages reveal Archean, Paleoproterozoic, Mesoproterozic, and Neoproterozoic events with the principal source could mainly belong to Paleoproterozoic magmatic lineage. Some of the Paleoproterozoic magmatic zircons were probably sourced from two mica granite found within the local geology, whereas the remaining zircons have features indicating source rocks within the Congo Craton. We suggest that the geologic history of these zircons is related to crustal-scale magmatic and/or tectono-metamorphic events, possibly linked to Eburnean and Pan-African orogeny.

New Insights into Pre-to-Post Ediacaran Zircon Fingerprinting of the Mamfe PanAfrican Basement, SW Cameroon: A Possible Link with Rocks in SE Nigeria and the Borborema Province of NE Brazil

“…The calculated Th/U ratios (0.007-2.156) are based on [5,11,23,24], which show predominantly core and growth zones with metamorphic affiliations (with Th/U ratios < 0.07) and a few crystallized magmatic or growth areas (with Th/U ratios ranging from 0.86 to 2.16). The studied zircons are therefore composed of (1) zircons with a magmatic or metamorphic core and ( 2 [5,11,23] [6,35]) show that they were mostly formed in magmatic melts during this period (subdivided into 830-849 Ma, 701-787 Ma, and 637-673 Ma). This can suggest a progressive crystallization in a crustal magmatic melt during Mid Neoproterozoic time.…”

“…The few Late Mesoproterozoic and Early Neoproterozoic magmatic spots in the core of some crystals may show inheritance. The Th/U ratios (0.003-0.121, a metamorphic-anatectic signature [6,11,23,32]) in few Mid to Late Neoproterozoic spots show that their host zircons registered Mid to Late Neoproterozoic anatectic-metamorphic events (crystallization and recrystallization). The magmatic nature (Th/U > 0.3) of part of the recrystallized portions may be due to their formation in magmatically derived aqueous fluids, as proposed by [30,125].…”

“…Zircon geochronology is one of the key methods used to determine the ages of geological processes, including magmatic crystallization, different post-crystallization episodes [1][2][3][4][5][6][7], fingerprinted metamorphism [2,[8][9][10][11][12][13][14], and hydrothermal activity [15][16][17][18]. It also helps for provenance studies and paleogeographic reconstitution (e.g., [19][20][21][22][23][24][25][26][27][28][29]). Coupled with zircon morphology-textural analyses and U-Th composition helps to better belt characterized by thrust and shear zones, which have been correlated with similar structures in northeastern Brazil and which are late collisional features [39].…”

Determining the source of placer gold in the Anaconda metamorphic core complex supradetachment basin using detrital zircon U-Pb geochronology, western Montana, USA

“…Three studies in the Witwatersrand basin of South Africa used U-Pb geochronology of detrital zircons to gain insight into the controversial origin of gold deposited in quartzite reefs (Ruiz et al, 2006;Koglin et al, 2010;Zeh and Gerdes, 2012). The technique has also been applied to fingerprint to source of gem and gold placers in the Mamfe Basin of southwestern Cameroon (Kanouo et al, 2012(Kanouo et al, , 2018. More recently, researchers have also begun pairing the U-Pb ages of detrital zircons with corresponding geochemical signatures (such as Lu-Hf isotopic data), which serve as separate provenance tracers for mixed sediments (Zeh and Gerdes, 2012;Kanouo et al, 2018).…”

“…The technique has also been applied to fingerprint to source of gem and gold placers in the Mamfe Basin of southwestern Cameroon (Kanouo et al, 2012(Kanouo et al, , 2018. More recently, researchers have also begun pairing the U-Pb ages of detrital zircons with corresponding geochemical signatures (such as Lu-Hf isotopic data), which serve as separate provenance tracers for mixed sediments (Zeh and Gerdes, 2012;Kanouo et al, 2018).…”