The Pan-African Biotite-Muscovite Granite and Amphibole-Biotite Granite of Doua (Central Cameroon): Zircon Features, LA-MC-ICP-MS U-Pb Dating and Implication on Their Tectonic Setting

Abstract

The Doua area belongs to the Adamawa-Yadé domain (AYD) of the Central African Fold Belt (CAFB) in Cameroon. It is crossed by the Central Cameroonian Shear Zone (CCSZ). The purpose of this research is to determine the tectonic setting of granites of the studied area, based on their petrography, zircons feature and their ages. Petrographicaly, the Doua area is made up of plutonic rocks hosted in an ortho or paraderivative metamorphic basement. Amphibole-biotite granite (ABG) and biotite-muscovite granite form hills and crop out on the hill side, as flagstones in the valley or river bed, and as huge blocks. Amphibole-biotite granite is granular in texture and made up of amphibole, biotite, feldspar, accessory minerals (Sphene, zircon, and apatite) and secondary minerals (sericite). Biotite-muscovite granite (BMG) is granular to granular porphyritic in texture, made up of biotite, muscovite, plagioclase, K-feldspar, quartz, accessory minerals (zircon, opaques minerals) and secondary minerals (chlorite, sericite). ABG show elongated zircon grains with well-developed magmatic oscillatory zonation. LA-ICP-MS U-Pb data from these zircons define a concordia age of 607 ± 3 Ma and considered as crystallization age of the granite. BMG shows zircon with various shape and various internal structures (oscillatory zonation, sector zonation, blurred oscillatory zonation …) which are divided into two sets. The first set regarded as xenocryst from Paleoproterozoic granitoids emplaced at 2126 ±36 Ma or from sediments which detritus comes from such granitoids. The second set of zircons shows effects of recent lead lost and a subconcordant U-Pb age of 646 ± 39 Ma . ABG was emplaced during the D3 deformational phase, date at 607 ± 3 Ma , while BMG was trigger because of syn-D1 activity of the CCSZ at 647 ±46 Ma in association with the collisional process.

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

“…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., 2011, 2017; Kanouo et al., 2021; Lassere, 1961; Ngako et al., 1991, 2003, 2008; Njanko, et al., 2010; Owono, 2008; Toteu et al., 2008) (Figure 1c). The name Lom series designates, in reality, a set of epi‐to‐mesozonal metasediments, constituted of volcano‐sedimentary 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).…”

“…Several geological studies have been carried out in the Adamawa region in general, and in the Simi locality in particular, for geological surveys (Diguim et al, 2017;Ganwa et al, 2011Ganwa et al, , 2017Lassere, 1961;Le maréchal & Vincent, 1971;Ngako et al, 1991Ngako et al, , 2003Ngounouno et al, 2001;Njanko, et al, 2010;Toteu et al, 2008). These studies situate Adamawa in the Central Cameroon Domain (or Adamawa-Yade Domain), which is one of the subdivisions of the North Equatorial Pan-African Channel (Figure 2).…”

“…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).…”

Bastnaesite K-9: A Homogenous Natural Reference Material For In-Situ U–Pb And Th–Pb Dating

“…Data reduction for U-Pb was done using algorithms of Schmitz and Schoene (2007) 14 and Th-Pb was calculated using PBDAT 15 using the decay constants of Jaffey et al (1971) 16 and assuming a Th/U ratio of the magma of 4. Any common Pb in excess of the blank amount is assumed based on the Stacey and Kramers (1975) 17 model at 100 Ma.…”