Papers by Periclex Martial Fosso Tchunte
Minerals, Apr 30, 2018
The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt... more The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB), is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG). It is made of two main rock groups: (1) the metaluminous barren muscovite granite (MsG) and (2) the Nb-Ta bearing peraluminous leucogranite (MsL) which expresses four subtypes. The evolved Rare-element MsL is subalkaline, slightly peraluminous (ASI = 1.01-1.21), and it displays flat REE chondrite-normalized patterns with a strong negative Eu anomaly (Eu/Eu* = 0.02-0.20). It belongs to the peraluminous low phosphorus Rare-element Granites and L-type igneous rocks, as shown by the relatively low Zr/Hf (4.8-14) and Nb/Ta (1.4-9.0) ratios and the positive slope of the Zr-Hf-Nb-Ta profile in spider diagrams. The rare-element-bearing mineral is represented by columbite-group minerals (CGM) and other Nb-Ta-oxides (Nb-rutile and pyrochlore supergroup minerals). The CGM is classified as Mn-columbite, with Ta# and Mn# ratios increasing from core to rim. Two stages of mineralization are identified; the earliest stage (CGM-I) consists in scattered tabular or prismatic euhedral grains that were related to magmatic fractionation. The latest stage (CGM-II) is expressed as a Ta-rich Mn hydrothermal CGM episode represented as rims and/overgrowths around and/or as veinlet crosscutting CGM-I or in cleavage planes of muscovite. The U-Pb dating of columbite and monazite of the Mayo Salah leucogranite indicates a late-Neoproterozoic magmatic-hydrothermal mineralization event from 603.2 ± 5.3 to 581.6 ± 7.2 Ma, as consistent with both late D 2 to D 3 events that were recorded in the CAFB in Cameroon, and the associated continental collision environment. The Nb-Ta mineralization of the Mayo Salah pluton provides evidence for the presence of RMG in Northern Cameroon of CAFB, and its temporal association with the youngest period of metallogenic epoch of Nb-Ta-ore formation in Africa associated to Pan-African times.
Petrography and geochemistry of the Letta Pan-African plutonic and metamorphic rocks in eastern part of the Central African Fold Belt in Cameroon
Arabian Journal of Geosciences
Journal of Geoscience and Environment Protection, 2021
The Pan-African/Brasiliano orogenic belts are a part of numerous Neoproterozoic orogenic belts th... more The Pan-African/Brasiliano orogenic belts are a part of numerous Neoproterozoic orogenic belts that belong to the long-lived orgenic cycle that distancing phase started at the Tonian around 1.0 Ga. The Tonian magmatism fairly documented in the Neoproterozoic belts of Borborema Province (NE-Brazil), seemed so far inexistent in the Central African Orogenic Belt (CAOB) although these two belts were geologically correlated. Through the Lu-Hf geochronological analysis on zircon of tonalite, the present work, coupled with the previous data, suggests the existence of a Tonian age magmatism in the Central Cameroon Domain of the CAOB although the latter is much reworked. The Nguesseck tonalite outcrops in the northern part of the Mbé-Sassa-Mbersi region, in the northern edge of Central Cameroon Domain of the CAOB and in the Tcholliré-Banyo shear zone (TBSZ). The Lu-Hf data obtain on the zircon grains of this tonalite reveal juvenile Hf TDM age of ca. 1.0 Ga. This age, combined to the previous geochemical data suggests that the protholites of this tonalite would have extracted from the source during the distancing phase (rifting and oceanization) of the Pan-african/Brasiliano orogeny at the early Neoproterozoic.
Open Journal of Geology, 2020
In the syenitic pluton of Guider (593 ± 4 Ma) in the NorthWest Cameroon domain of Central African... more In the syenitic pluton of Guider (593 ± 4 Ma) in the NorthWest Cameroon domain of Central African Fold Belt, mineralized N-S to NE-SW vertical or sub-vertical quartz and quartz feldspar veins has been recently identified. In this contribution, we present petrography and mineralogy of these veins, in order to constrain their genesis and emplacement mechanisms based on detailed field work, petrographic studies and chemical characterization of minerals by using an electron probe microanalyser (EPMA). Field observations and vein microstructures show that the emplacement of the veins has been controlled by the dextral N-S trending strike-slip shear zones related to the regional D2 deformation phase. The results of mineralogical analysis reveal the co-presence of silicates and metallic minerals that include magnetite, ilmenite, pyrite, bismuthite, galena (very rare) and sulphide complexes (BiPbS, BiAgPbS, FeBiPbCuS, BiFe(TeS), FeBiPbS, BiPbCuS). The gangue is represented by quartz (quartz 1, quartz 2 and quartz 3), feldspars, sericite, chlorite, yellowish brown clay minerals, and hematite. The textural relationships between sulphides, quartz and alteration products show that the mineralization is essentially syn-to late-D 2 and suggest that syenitic country rock and dextral shear zones have played an important role in the metallogenesis of these veins. This mineralization shows characteristics for copper-bearing calc-alkaline deposits, but differs from these by its more extensive alteration and its abundance in hematite. Substitutions of Al(IV) by Si(IV) in sericite associated with the sulphide mineralization and cataclastic deformation suggest that the temperature of trapping of the fluids is between 230˚C and 275˚C.
Journal of Geosciences and Geomatics, 2018
Field petrographic and structural data of the Mbé-Sassa-Bersi area exposed two main group of rock... more Field petrographic and structural data of the Mbé-Sassa-Bersi area exposed two main group of rock (metamorphics and plutonics) which were affected by polyphase deformation. The structural evolution is marked by four deformation phases called D 1 , D 2 , D 3 and D 4. The geometrical arrangement of D 1 structures (flat-lying foliation, horizontal lineation, recumbent folds and overlapping) allow to linked this deformation phase to tectonic nappe verging toward SSE. The second deformation stage (D 2) corresponds to simple shear dominated transpression and characterized by the evolution of the Tcholliré-Banyo shear zone (TBSZ) that showing sinistral movement. The third deformation phase (D 3), is marked by strain partitioning induced by transpression and links to the evolution of the Central Cameroon shear zone (CCSZ) that displays dextral motion. D 1 , D 2 and D 3 are associated to migmatization, development and emplacement of granitic magmatism. During D 2 and D 3 , the magmatic rocks are emplaced under the control of the two main crustal shear zones (TBSZ and CCSZ). D 4 deformation is responsible for the development of faults, fracture and joints and corresponds to brittle tectonic. The main NW-SE direction of faults and fractures suggest that D 4 stage shows traces of the Benue trough. On the whole, Nappe tectonic, followed by transpressive tectonic are the main tectonic type developed during the Pan-African Orogeny in Central North Cameroon.
Minerals, 2018
The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt... more The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB), is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG). It is made of two main rock groups: (1) the metaluminous barren muscovite granite (MsG) and (2) the Nb-Ta bearing peraluminous leucogranite (MsL) which expresses four subtypes. The evolved Rare-element MsL is subalkaline, slightly peraluminous (ASI = 1.01-1.21), and it displays flat REE chondrite-normalized patterns with a strong negative Eu anomaly (Eu/Eu* = 0.02-0.20). It belongs to the peraluminous low phosphorus Rare-element Granites and L-type igneous rocks, as shown by the relatively low Zr/Hf (4.8-14) and Nb/Ta (1.4-9.0) ratios and the positive slope of the Zr-Hf-Nb-Ta profile in spider diagrams. The rare-element-bearing mineral is represented by columbite-group minerals (CGM) and other Nb-Ta-oxides (Nb-rutile and pyrochlore supergroup minerals). The CGM is classified as Mn-columbite, with Ta# and Mn# ratios increasing from core to rim. Two stages of mineralization are identified; the earliest stage (CGM-I) consists in scattered tabular or prismatic euhedral grains that were related to magmatic fractionation. The latest stage (CGM-II) is expressed as a Ta-rich Mn hydrothermal CGM episode represented as rims and/overgrowths around and/or as veinlet crosscutting CGM-I or in cleavage planes of muscovite. The U-Pb dating of columbite and monazite of the Mayo Salah leucogranite indicates a late-Neoproterozoic magmatic-hydrothermal mineralization event from 603.2 ± 5.3 to 581.6 ± 7.2 Ma, as consistent with both late D 2 to D 3 events that were recorded in the CAFB in Cameroon, and the associated continental collision environment. The Nb-Ta mineralization of the Mayo Salah pluton provides evidence for the presence of RMG in Northern Cameroon of CAFB, and its temporal association with the youngest period of metallogenic epoch of Nb-Ta-ore formation in Africa associated to Pan-African times.
The geologic record of the exhumed root of the Central African Orogenic Belt in the central Cameroon domain (Mbé – Sassa-Mbersi region)
Journal of African Earth Sciences, 2019
Journal of African Earth Sciences, 2017
The Ngaound er e granite pluton, in Central-North Cameroon, located near the Central Cameroon She... more The Ngaound er e granite pluton, in Central-North Cameroon, located near the Central Cameroon Shear zone (CCSZ), and previously studied for its petrography and geochemistry, is characterized by the absence of macroscopic markers of deformation. In this study, we report microstructures and magnetic fabrics (AMS) of this pluton and discuss the relationship with the Pan-African evolution of the CCSZ. The pluton consists of a porphyritic Hbl-Bt-monzogranite at its rim and a porphyritic biotite-granite at its core, a petrographic distribution denoting a normal zoning pattern, i.e. more silicic toward the centre. As expected, magnetic susceptibilities values also exhibit a zoning pattern in agreement with petrographic zonation. Thermomagnetic data indicate that this pluton is dominantly ferromagnetic in behaviour. As indicated by its microstructures, the pluton has suffered a continuum of deformation from the magmatic state to the high temperature solid-state during magma crystallization and solidification. The magnetic foliations dominantly strike NE-SW and dip moderately to steeply and the lineations mostly plunge shallowly to the NE or SW, roughly parallel to NE-to ENE-trending Central Cameroun Shear Zone (CCSZ). The foliation poles define a girdle pattern with a zone axis (52 /11) rather close to the best line of the lineations (44 /21). These fabrics correlate with the structures of the country rocks ascribed by several workers to a regional transpression. Toward the margins of the pluton, particularly the northern one, the lineations tend to rotate from NE to N in azimuth. This change is interpreted as due to strain partitioning, simple shearing with NE-SW extension being relayed by compression toward the northern pluton border. This new magnetic fabric study suggests that the Ngaound er e pluton (poorly dated at c. 575 Ma) was emplaced during the late stages of the CCSZ dextral transpressive movement. It also provides some more constraints on the correlation between the CCSZ system and the shear zone system of NE-Brazil.
Journal of African Earth Sciences, 2017
Satellite map of the study area with the location of dated samples, some structures, microstructu... more Satellite map of the study area with the location of dated samples, some structures, microstructures and kinematic markers in the Tcholliré batholith.
International Journal of Geosciences, 2015
In this article, we discussed about the petrography and geochemistry of magmatic rocks of the Mbi... more In this article, we discussed about the petrography and geochemistry of magmatic rocks of the Mbip massif located SW of Tcholliré, in Central North Cameroon (Central African Fold Belt). Petrographic study shows that this massif is made of granodiorite, amphibole-biotite granite, and biotite granite which often contain enclave of mafic rocks (gabbro). Granodiorites and granites show porphyritic texture and consist dominantly of plagioclase and alkaline feldspar phenocrysts, quartz, biotite and often few amphibole. The gabbro enclaves are characterized by a granular porphyroid texture constituted of amphibole, plagioclase and olivine phenocrysts, all in a matrix of small crystals of plagioclase, olivine, amphibole, pyroxene and opaque minerals. All the analyzed rocks provide geochemical features of sublkaline serie and have nothing to do with the alkaline nature previously signaled in the former works. Granodiorites and granites are shoshonitic to calc-alkaline strongly potassic affinity consistent with emplacement in the continental collision setting. They present positive anomalies in Rb, Th, U; negative anomalies in Sr, P, Ti, Nb, Ta and some facies contain hydrated minerals such as amphibole. These characters are consistent with crustal and mantle contribution in their genesis. The mafic rocks (gabbro) have geochemical characteristics conferring a mantle origin, as confirmed by the high Mg# value (49.9). On the whole, the fractional crystallization of the magma formed by melting of crustal material and the magmat-* Corresponding author. E. N. Negue et al. 762 ic mixing are the main petrogenetic process in the Mbip massif. Petrographic studies and geochemical data shows that the Mbip massif was emplaced in an active continental margin, into transitional regime from the end of maximum compression to the beginning of relaxation.
Field studies, Landsats 8 OLI/TIRS processing and the digital elevation model of SRTM images perm... more Field studies, Landsats 8 OLI/TIRS processing and the digital elevation model of SRTM images permit us to map the Mokong area, region situated in arid zone and located to the Northen part of the central African Orogenic belt in Cameroun. The use of Landsat’s number 3 band of made it possible to highlight the lineaments. It has been noticed after analyses that the maximum number of lineaments are oriented N-S direction. The second major trends of lineaments in the study area are respectively, ENE-WSW, E-W and SSE-NNW. The landsat OLI/TIRS processing (colorful composition, band math, and principal component analysis) are permitted to discriminate four mains rocks types: gneisses-amphibolite; biotite granite, diorite-granodiorite and tonalite. All those facies are partially covered by alluvial deposits in the southern erea. The digital elevation model has permitted to identify some volcanic cover. The method used in this work offers promising prospects for geological mapping of arid re...
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Papers by Periclex Martial Fosso Tchunte