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![Geological map of the western Adamawa Yade domain [26]](publication/348758163/figure/fig2/AS:11431281115518892@1674965673837/Geological-map-of-the-western-Adamawa-Yade-domain-26.png)
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![Geological map of Cameroon modified after [10]. Fault system comprises...](publication/348758163/figure/fig1/AS:11431281115527381@1674965673754/Geological-map-of-Cameroon-modified-after-10-Fault-system-comprises-the_Q320.jpg)
![Geological map of the western Adamawa Yade domain [26]](publication/348758163/figure/fig2/AS:11431281115518892@1674965673837/Geological-map-of-the-western-Adamawa-Yade-domain-26_Q320.jpg)
The Tikar plain is located on the Cameroon Central Shear Zone. It is also part of the North Equatorial Pan-African Belt. It is formed of granitoids intruded in places by mafic and intermediate dykes. The mafic dykes are essentially banded gabbros composed of plagioclases, pyroxenes, amphiboles, biotites and opaques. Their textures range from porphy...
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Bhavani Complex, part of the Palghat Cauvery Shear Zone in Southern Granulite Terrain of Peninsular India, is comprised of petrological and geochemical characters of high temperature and pressure domains manifested by distinctive reaction textures in granulitic facies rocks. The study is focused on field relation, petrological and geochemical inter...
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... Unlike the volcanic edifices of the Cameroon Volcanic Line (CVL), the Central Cameroon Shear Zone (CCSZ) consisting mainly of granites, gneisses and mylonites hosts very few mafic rocks. Despite this rarity, some mafic dykes have been discovered in the Magba [18] and Njimom [19] areas in the CCSZ and their origin and tectonic setting have been discussed. However, in the Mfengou-Manki area, columnar jointed basalts were not observed. ...
... Located in the southern part of the Adamawa Yade domain (Central domain) (Fig. 1), precisely within the Central Cameroon Shear Zone (CCSZ), the Foumban-Magba area (hosting the study zone) is made up of granitoids subdivided into granites, gneisses, mylonites and migmatites and few mafic to intermediate rocks [18,[26][27][28][29]. The Central Cameroon Shear Zone is a Pan-African mega structure made up of lineaments oriented N70E and extending from Sudan into northeastern Brazil [29]. ...
... The Central Cameroon Shear Zone is a Pan-African mega structure made up of lineaments oriented N70E and extending from Sudan into northeastern Brazil [29]. This fault network allowed the upwelling of the mafic rocks magma following the C 2 shear axes and their emplacement within the granite and gneiss substratum [18]. The mafic rocks are high-K calc-alkaline to shoshonitic and are situated in the Magba area within the Foumban-Magba Zone. ...
In the Central Cameroon Shear Zone, several studies were focused on granitoids and very few on mafic rocks. Here we report the petrography, geochemistry and mineralogy of the Mfengou-Manki mafic rocks in order to constrain their petrogenesis and tectonic settings and the role of lithospheric and asthenospheric mantle sources in their genesis. The studied mafic rocks are subdivided into columnar jointed basalts and mafic dykes. Clinopyroxene thermobarometry indicates that the mafic dykes crystallized at a temperature of 1071 to 1193 °C and a pressure of 4 to 12 kbar while the columnar jointed basalts emplaced at a temperature of 1064 to 1152 °C and 2 to 13 kbar pressure. The mafic dykes and columnar jointed basalts present high La/Sm, Sm/Yb, Nb/Yb and Th/Yb ratios, indicating garnet to spinel transition zone mantle source. The multi-element diagram of the mafic dykes display enrichment in Nb, Ta, Pb and Ti and depletion in Th, U, Ce and Zr compared to that of the columnar jointed basalts (slight depletion in Nb and Ta and pronounced depletion in U, Pb and Zr and enrichment in Cs, Ba and Rb) indicating the little involvement of the sub-continental lithospheric mantle to the formation of the columnar jointed basalts. The Nb/La ratio > 1 for the mafic dykes and < 1 for the columnar jointed basalts also suggest the derivation of the mafic dykes from the asthenospheric mantle and the columnar jointed basalts from the mixed lithospheric-asthenospheric mantle due to the sub-continental lithospheric mantle delamination under the Central Cameroon Shear Zone.
... The Tikar plain, situated in the Cameroon Central Shear Zone, is part of the North Equatorial Pan-African Belt. It is formed by granitoids rocks intruded sometimes by mafic and intermediate dykes [14]. The mafic dykes are essentially banded gabbro with porphyroblastic to porphyritic textures and are composed of plagioclases, pyroxenes, amphiboles, biotite and opaque minerals. ...
This paper studied Late Iron Age ceramic fragments from Nditam village (Centre Region, Cameroon), the technological features and deduced the type of the raw materials used to produce them by combining different analytical techniques based on X-ray fluorescence, powder X-ray diffraction, thermogravimetry, polarized optical microscopy, spectrophotometry and hydric tests. Macroscopic observations suggest the existence of three types of ceramics according to their colour, black, greyish and red, in the two opposite surfaces, outer (or external) and inner (internal). The chemistry indicates that non-calcareous clayey material was used for ceramic production. The correlation between mineralogy, petrography and the geology of the region suggests a local production of ceramics. Moreover, the chemistry of the samples confirms the existence of the three macroscopic groups and suggests the use of local raw materials for their production. From the mineralogical point of view, quartz, feldspar and mica (biotite and muscovite) were identified in all the samples, while kaolinite and amphibole were detected in some of them. The differences in the mineralogy may indicate some variations in the firing temperature, being lower in the ceramics containing kaolinite compared to the other samples. All the samples have similar water absorption behaviour. According to the colours of the ceramics, a prevalence of oxidising firing conditions was present in the kilns. However, partial reducing and short duration firing conditions were also possible. Comparative study with the mineralogy of ethnographic ceramics from southern Cameroon shows some similarities and suggests a continuity in the use of different local clay pits in this region over time.
... The NE part of the pluton consists of microgranite and granite porphyry, and these rocks are affected by fracture-controlled quartz-mica and quartz-topaz greisen alteration and by large-scale pervasive argillic alteration. Erosional relics of rhyolite cover the intrusive rocks and the basement (Tchameni et al., 2006;Ngako et al., 2008;Ntieche et al., 2021). Tin mineralization occurs in quartz stockworks, silicified breccia and greisen bodies, and residual weathering deposits in the NE part of the pluton, and is mined at a small scale (ESM Fig. 1). ...
... In this study, field descriptions of the dolerite dykes cross-cutting the Pan-African basement (DPB) and the dolerite and gabbroic dykes cross-cutting the Cretaceous sedimentary basin (DGCSB) are used together with petrographic, bulk-rock geochemistry, as well as Sr-Nd-Pb isotopic data to constrain the geodynamic setting and ori- (Aka et al., 2018;Asaah et al., 2022;Huang et al., 2021;Keutchafo Kouamo et al., 2019;Mey Atour et al., 2020;Ntieche et al., 2021;Silpa et al., 2021). Contrary to other geological formations of the CL, basaltic dykes have been less studied and those with transitional/subalkaline character have been described in some zones of the continental segment of this line (Aka et al., 2018;Asaah et al., 2022;Keutchafo Kouamo et al., 2019;Ngounouno et al., 2001;Tchaptchet et al., 2017;Tchouankoue et al., 2012;Tchouankoue et al., 2014). ...
In this study, field descriptions of the dolerite dykes cross‐cutting the Pan‐African basement (DPB) and the dolerite and gabbroic dykes cross‐cutting the Cretaceous sedimentary basin (DGCSB) are used together with petrographic, bulk‐rock geochemistry, as well as Sr – Nd – Pb isotopic data to constrain the geodynamic setting and origin of these mafic (basanite, basalt and basaltic andesite in composition) rocks that outcrop in the Figuil–Léré area. The DPB dykes are alkaline with SiO 2 of 46.63–49.03 wt% and MgO of 3.93–7.11 wt%. In contrast, the DGCSB dykes are subalkaline with SiO 2 ranging between 50.24 and 53.16 wt% and MgO fluctuating between 5.22 and 7.90 wt%, comparable to dykes described in other regions of the Cameroon Line (CL). The rocks studied belong to the tholeiitic series and were emplaced in within‐plate basalts (WPB) and mid‐ocean ridge basalts (MORBs) setting. The variations in major and trace elements from the basanite to basaltic andesite compositions are dependable with fractional crystallization (FC) of different mineral phases such as opaque minerals, olivine, clinopyroxene, amphibole and alkali feldspar. Most samples exhibit negative Nb–Ta and positive Sr anomalies, which together with the negative correlation between MgO and ⁸⁷ Sr/ ⁸⁶ Sr, and isotopic ratio of ²⁰⁶ Pb/ ²⁰⁴ Pb <19.5 (18.27–19.49) suggests interactions of crustal components. Nevertheless, this contamination seems limited because there is a positive correlation between SiO 2 and ¹⁴³ Nd/ ¹⁴⁴ Nd plot and low Ba contents (72–210 ppm) of the samples compared to the mid‐continental crust (259–628 ppm). Trace element modelling proposes a derivation of the Figuil–Léré dykes from parental melts generated by 4%–15% partial melting of a source containing garnet peridotite in the mixed lithospheric–asthenospheric mantle. The isotopic data of the dykes studied with hybrid magma composition are characterized by more radiogenic ⁸⁷ Sr/ ⁸⁶ Sr, ¹⁴³ Nd/ ¹⁴⁴ Nd and ²⁰⁶ Pb/ ²⁰⁴ Pb isotopic ratios with a dominant mixing of depleted MORB mantle (DMM)–enriched mantle 1 (EM1)–enriched mantle 2 (EM2), like those of other mafic dykes of the CL.
... Varied types of deposits are located along the Cenozoic CVL, such as; clastic deposits (Kenfack et al., 2011;Tchouatcha et al., 2022b) or chemical deposits (Bisse et al., 2018;Tchouatcha et al., 2018), and the Precambrian CCSZ (Ngako et al., 1991;Ntieche et al., 2021) reactivated during the Cenozoic periods (Le Marechal and Vincent 1971;Ngangom, 1983;Dumont, 1984Dumont, , 1987Tchouatcha et al., 2010Tchouatcha et al., , 2016. ...
Terrigenous sediments located along the Central Cameroon Shear Zone and the Cameroon Volcanic Line, respectively, in the Mbere and Laopanga basins located in the Adamawa Region, were subject to provenance, paleoenvironmental deposition,
and tectonic setting studies, using palynological, mineralogical, grain shapes and facies analyses. The stratigraphic succession consists of two positive sequences and seven lithofacies (Gcm, Gmm, Sm, Sh, St, Fml, and Fh) in the Mbere Basin
and fve positive sequences and six lithofacies (Gcm, Gmm, Ghm, Sm, Sh, and Fml) in the Laopanga Basin, deposited in an active tectonic context. The deposits vary from proximal to sub-distal in the Mbere Basin and are mainly proximal in the
Laopanga Basin. The heavy mineral analysis highlights several distributing sources, with minerals from basic volcanic rocks (olivine and basaltic hornblende), metamorphic rocks (kyanite, andalusite, and sillimanite), minerals from metamorphic and volcanic rocks (augite, diopside), and minerals common to all types of rocks (zircon, garnet, and hornblende), indicating the heterogeneous source rocks. The deposits lack any marine species, and the pollens and spores’ assemblages include Ricceaceae, Chenopodiaceae, Malvaceae, Gramineae, Compositae. The available geochronological data of volcanic rocks suggest a Plio-Pleistocene age to these sequences. Sedimentary structures and palynological data indicate a continental fuvio-lacustrine environment of deposition. The lightly abundant kaolinite and the presence of ferric minerals associated to sporopollenite species indicate a more or less hot and semi-arid climate. The Phanerozoic reactivation of Precambrian faults has led to the setting up of continental depression as in the cases of Laopanga and Mbere basins.
... It hosts the huge shear area also called the Cameroon Central Shear Zone (CCSZ) extending from Foumban to Banyo Ntieche et al. 2020). The granitoids from the central domain emplaced around 600 Ma are syn to post-tectonic and mainly present high-K calc-alkaline affinity (Ntieche et al. 2017(Ntieche et al. , 2021. The central domain also presents Paleoproterozoic to Archean remnants of about 2.1 Ga (Toteu et al. 2001). ...
Situated at the central part of the Central African Fold Belt in Cameroon, the Shissa pluton consists of two-mica granites and biotite granites. All the granites are shoshonitic in nature and present high K2O/Na2O ratios (1.50–2.42). The biotite granites are subaluminous and present I-type character (A/CNK ranges 1.0–1.1). The two-mica granites are typically two-mica alkali granites with S-type signature (A/CNK ranges 1.1–1.21) and Al2O3-rich (Al2O3 = 12.86–13.40 wt.%) than the biotite granites (Al2O3 11.24–13.26 wt.%). The Shissa granites multi-element patterns show enrichment in LILE such as Rb, Th, U, and Pb and are depleted in HFSE such as Ti, Ba, and P, suggesting the crustal source with an inherited arc signature. All the granites present the Nb/Th ratio (0.2–1.2) significantly lower than that of the mantle (> 15), indicating the crustal source for the granites. The chemistry of the biotites suggests that the biotite granites are generated from the partial melting of already differentiated metabasite to metatonalitic source under high oxidizing conditions at the temperature between 908 and 1009 °C, while the two-mica granites were formed under moderated oxidizing conditions between 836 and 917 °C from the assimilation of felsic crustal component by the biotite granite magma during its ascent. The Shissa granites formed at a relatively hydrous environment (4 wt.% of the water content). The upwelling of the asthenosphere through slab break-off may have favored the partial melting of the meta-igneous lower crust by supplying the thermal anomaly as it is the case in the Central African Fold Belt in Cameroon. The whole-rock geochemistry and the biotite mineral chemistry suggest the collisional tectonic setting for the Shissa granite as several granitoid plutons in the CAFBC.
... The precision is always less than 1%. The procedure is explained in Ntieche et al. (2016Ntieche et al. ( , 2021. The mineral chemistry was done using a CAMECA SX 100 (15 kV, 10 nA) electron probe micro-analyser (EPMA) at the Indian Institute of Science, Bengaluru, India. ...
Situated in the Tikar plain, the Nkoula granitoid suites consist of granites, quartz monzonites and syenites. The petrography, mineral chemistry and whole-rock geochemistry of the studied granitoids were done. The rocks are mainly made up of quartz, K-feldspar, plagioclase, amphibole, biotite ± sphene ± epidote. They are I-and S-type, metaluminous to peraluminous, magnesian and belong to high-K calc-alkaline to shoshonitic series. K-feldspars are orthoclase and plagioclases have the chemical composition of oligoclase. Biotites are reequilibrated primary Mg-rich while amphiboles are magmatic, calcic and essentially magnesian. All the granitoids display LREE enrichment and HREE depletion with negative Eu anomaly. The primitive mantle normalized trace element patterns display Rb, Ba, U, Th and Pb enrichment and depletion in Nb, Ta, Ti and P. The major and trace element variations indicate that fractional crystallization plays an important role during the magmatic processes of the S-type magma. The trace element ratios Ba/Rb, Nb/Ta, Y/Nb, Th/La, Sm/La, Hf/Sm and Ta/La, along with the biotite and amphibole chemistry, point to a crust-mantle mixed source for the Nkoula granitoid suites. The granitoids emplaced in the syn-collisional and volcanic arc setting. The most likely processes for the Nkoula granitoid consist of the partial melting of the subducted slab and the probable contribution of a mantle component. The break-off of the subducted slab may have favored the upwelling of the asthenosphere that supplies heat for the partial melting of the slab and crust components. The Nkoula granitoid magma displays 3–5 wt.% of water and was formed under high oxidizing conditions. They were emplaced at relatively shallow depth (3–9 km) and crystallized at about 800–900 °C in the Adamawa-Yade continental crust due to the subduction of the Yaounde oceanic crust under the Adamawa-Yade domain during the Pan-African orogeny.
... Worldwide, several studies concerning mafic dyke's interactions with host crustal rock/magma and their emplacement process has been done (Vermon et al., 1988;Frost and Mahood, 1987;Andersson, 1991;Neves and Vauchez, 1995;Marcus et al., 1997;Piochi et al., 1999;Baxter and Feely, 2002;Santhosh and Vikoleno, 2006). It has been shown that, in several granitoid plutons, mafic dykes or enclaves more often host deformation structures formed during their ascent and emplacement in the crust following faults or shear axis (Ntieche et al., 2017;Ntieche et al., 2021). Mafic and felsic magmas are also generally used as petrological indicators of magama chamber process such as mixing or mingling (Jayananda et al., 2019;Jayananda et al., 2014;Elangovan et al., 2017;Jessica et al., 2002;Marcus et al., 1997;Piochi et al., 1999). ...
Field and petrographic studies of the Makenene area in the Central African Fold Belt in Cameroon reveals several features testifying the mafic and felsic magmas interactions and their coeval nature. They are: (1) the Mafic Magmatic Enclaves (MMEs) scattered throughout the Makenene granitoid pluton and displaying sub-rounded shape and back veining, (2) flow structures consisting of schlierens at the tails of MMEs, folded MMEs along with felsic host granitoids with hinge indicating the flow direction, (3) irregular or cuspate boundary between MMEs and host granitoids, (4) quenching of apatite and biotites minerals, (5) MMEs enclosing other MMEs or felsic host granitoids. The mafic magma injection operated during at least four stages (from early to late crystallization state of the host magma) leading respectively to the formation of homogenized granitoid; sub-spherical MMEs scattered in the pluton; dismembered dyke and undisturbed synplutonic mafic dyke. The Makenene area registered four deformation phases (D1 to D4). The first two deformation phases occurred before the magmatism and migmatization events. The third phase is coeval to the magmatism and the migmatization period (at the Eburnean orogeny (2.08-2.07 Ga)). The fourth phase is related to the Panafrican orogeny.
Technical report for the Geological and Aquifer productivity map. AGES Technical Report 09
