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

Abstract

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 °C), ∑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.

Combined analysis of resistivity and induced polarization tomography for 3D modelling and preliminary volume estimation of the possible gold mineralization zones in the Simi locality, Adamawa, Cameroon

“…If we consider, for example, the chargeability sections of profiles L1, L2, L3, L5, L6 and L7 compared to the resistivity sections of the same profiles, we can easily associate the Hc2 anomalies to the vein intrusion zones, based on their geometry and previous analyses. These veins are, thus, intruded in a metasedimentary environment characteristic of the Lom (Kanouo et al., 2021; Tchameni et al., 2006; Toteu et al., 2001; Toteu et al., 2008). Because the objective here is to delineate zones of potential mineralization, the grids of inverted chargeability sections were categorized according to the range of chargeability and the correlation given in Table 1.…”

“…(Figure 1c). The name Lom series designates, in reality, a set of epi-to-mesozonal metasediments, constituted of volcanosedimentary and graphitic schists, quartzites and mica schists (Kanouo et al, 2021;Soba et al, 1991;Tchakounte, 1999;Tchameni et al, 2006;Toteu et al, 2001;Toteu et al, 2008;Vicat, 1998). It is known for its abundance of hydrothermal mineralization, of which gold is mined in an artisanal and semi-mechanized form by local populations and companies, respectively.…”

“…It is drained by seasonal streams (all tributaries of the Lom River) which are fed mainly by run-off water (Figure 1b). The compilation of previous geological studies shows that the geology of the study area is represented by the Lom series (Diguim et al, 2017;Ganwa et al, 2011Ganwa et al, , 2017Kanouo et al, 2021;Lassere, 1961;Ngako et al, 1991Ngako et al, , 2003Ngako et al, , 2008Njanko, et al, 2010;Owono, 2008;Toteu et al, 2008) F I G U R E 1 (a) Geological map of Adamawa: (1) Lower Cretaceous, (2) Lom series (Conglomerates, quartzites, sedimentary schists and volcano-sedimentary), (3) biotite and amphibole gneiss, (4) granulitic gneiss (Paleo-to-Neoproterozoic), (5) volcano-plutonism (Neoproterozoic), (6) post-tectonic granitoids (Neoproterozoic), ( 7) syn-to-late-tectonic granitoids (Neoproterozoic), (8) pre-to-syntectonic granitoids (Neoproterozoic), (9) faults, (10) shear direction, (11) boundaries of Simi locality, (12) study area; (b) orohydrographic model of Simi and its surroundings; (c) topographic variation in the study area. Source: Modified from Toteu et al (2008).…”

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

“…They are, therefore, zircons crystallized from crustal magmas. 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).…”

“…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].…”