Multiple Ediacaran tectono‐metamorphic events in the Adamawa‐Yadé Domain of the Central Africa Fold Belt: Insight from the zircon U–Pb LAM‐ICP‐MS geochronology of the metadiorite of Meiganga (Central Cameroon)

Abstract

One of the many orogeny cycles in Central Africa is the Pan‐African orogeny which took place during the Neoproterozoic era. In central Cameroon, the reworked materials are Archean to Palaeoproterozoic rocks of sedimentary and magmatic origin and subsequent granitoids. The metadiorite of Meiganga is a syntectonic magmatic rock, affected by three deformational phases. It is characterized by a schistosity highlighted by a banded structure related to migmatization and made up of green hornblende, biotite, plagioclase, quartz, chlorite, opaques minerals, apatite, zircon, and titanite. Zircon grains of the metadiorite are prismatic or roundish. Internally, they show oscillatory zonation, blurred oscillatory zonation, and sector zoning. Some grains portray an outer cathodoluminescence bright band with blurred oscillatory zonation and which transgress the inner oscillatory domain; zircons contain inclusions or are inclusion free. Laser‐ablation microprobe‐inductively coupled plasma‐mass spectrometry U–Pb data allow in relation with the internal structure of the zircon to decipher many tectono‐metamorphic steps in the Ediacaran phase of the Pan‐African Orogeny: (a) syntectonic emplacement of the dioritic protolith at 637 ± 5 Ma; (b) syn‐D2 melting process at 623 ± 2 Ma; (c) D3 time interval between 608 ± 2 and 562 ± 6 Ma; and (d) maximum age of the dextral movement of the regional shear zone at 570 ± 8 Ma. Ages founded in the studied metadiorite sample are recorded individually in different area of the Adamawa‐Yadé area of the Central African Fold Belt and the Borborema Province of NE Brazil, showing that the two domains underwent the same tectono‐metamorphic history during the Ediacaran period.

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).…”

“…The Central Cameroonian Domain within which the Adamawa Plateau is located is tectonically dominated by fault systems with directions ranging from N20E to N70E (Lassere, 1961;Ngako et al, 1991Ngako et al, , 2003Ngako et al, , 2008Njanko, et al, 2010;Toteu et al, 2008). Structural studies of the Adamawa domain highlight four deformation phases: D1, D2, D3 and D4 (Ganwa et al, 2011(Ganwa et al, , 2017Ngako et al, 1991Ngako et al, , 2003Ngako et al, , 2008Tchameni et al, 2006). The D1 phase is marked by flat foliation associated with isoclinal folds and an N110˚E-N140˚E stretching lineation that is locally well preserved.…”

“…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).…”

Geochemistry of the Neoproterozoic Mbondo-Ngazi Tina Metasediments, Adamawa Area, Central Cameroon: Source Provenance and Tectonic Setting

“…Of these three domains, the central domain or Adamawa-Yade Domain (AYD) has been widely investigated for the past two decades, but their geodynamic evolution remains controversial and/or unrevealed. Many studies have been mainly concentrated on petrogenesis of granitoids which are widespread in the central domain [7][8][9][10][11][12][13][14][15] and only few works on the metamorphic rocks [7,16,17,18,19] In comparison to the granitoids, the metamorphic rocks, especially metasedimentary rocks from the central domain have received very little attention even though sedimentary rocks contain a wealth of information about provenance and crustal evolution [20,21]. It is now well established that detrital sediments contains part of a record of geologic history.…”