Victor METANG

Nappe tectonics in the Matomb-Hegba area, South-Central Cameroon: Implications on the tectonic evolution of the Yaoundé Group in the Central African Orogenic Belt

Victor Metang, Henri Appolinaire Kenzo, Rose Noël Ngo Belnoun, Dior-Christelle Mboutchouang, Steve Franck Bamou-Wandji, Brigitte Domkam and 1 more

Geosystems and Geoenvironment

This paper documents the thrust tectonics in the Yaoundé Group using detailed field mapping and satellite imagery data. The litho-stratigraphic of the Matomb-Hegba area located W of the Pan-African Yaoundé series comprised two main metasedimentary units: (1) garnet-kyanite migmatites at the top, dated at 622 ± 43 Ma, and (2) garnet-rutile micaschists at the bottom, with ages ranging between 546 and 604 Ma. The contact between the two lithological units is materialized by a ductile shear zone evidenced by structural and remote sensing data: inversion of the foliation at the contact of the shear zone, P 2 folds with southern vergence, E-W to NE-SW sinistral shear planes, uniform dip (towards the SE) and several criteria indicating a sinistral and dextral kinematics respectively in light grey mylonites and in dark grey mylonites along the ductile shear zone. During D 2 deformation stage, subhorizontal S 2 foliation associated to NE-SW Lm 2 mineral lineations were developed in garnet-kyanite migmatites. The thrusting contact zone is characterized by mylonitized micaschists (light grey mylonites) and migmatites (dark grey mylonites) separated by talcschist and amphibolite boudins which would have served as a ‘‘soap layer’’ leading to the slipping of garnet-kyanite migmatites over garnet-rutile micaschists. The disposition of garnet-kyanite migmatites (sometimes outcrop in the form of klippes) over garnet-rutile micaschists, the presence of a ductile shear zone at the contact of the two lithological units, and the NE-SW mineral lineation suggest the existence of at least two tectonic nappes (garnet-kyanite migmatites and garnet-rutile micaschists) with NE-SW-trends in the Yaoundé Group. This nappe disposition induced by ductile shear corroborates well with the compressive shear tectonics as described in the NE of Brazil and in the northern and eastern part of the Saharan Block.

• #geological and geochemical analysis
• #geochemistry and geologic mapping
• #geological and geophysical studies worldwide
• #nappe

Anatexis of metadiorite from the Yaoundé area, Central African Orogenic Belt in Cameroon: implications on the genesis of in-source granodiorite leucosomes

Victor Metang, Emmanuel Nomo Negue, Sylvestre Ganno, Jonas Didero Takodjou Wambo, Marcel Astrid Ewolo Teme, Arnaud Cedric Teda Soh and 5 more

Arabian Journal of Geosciences

• #geological and geochemical analysis
• #high-pressure geophysics and materials
• #geochemistry and geologic mapping
• #geology

Petrology and geochemistry of the Pan-African high-K calc-alkaline to shoshonitic–adakitic Bapé plutonic suites (Adamawa-Yade block, Cameroon): evidence of a hot oceanic crust subduction

Jacqueline Numbem Tchakounté, Fuh Calistus Gentry, Aurélie Ngamy Kamwa, Victor Metang, Joseph Mvondo Ondoa, Charles Nkoumbou

International Journal of Earth Sciences

• #geological and geochemical analysis
• #geochemistry and geologic mapping
• #earthquake and tectonic studies
• #geology

New Data on the Genesis and Evolution of the Primitive Magmas of Mount Cameroon: Contribution of Melt Inclusions

Legrand Joseph Tchop, Pauline Wokwenmendam Nguet, Benjamin Ntiéche, Victor Metang, Jacques Dili Rake, Merlin Isidore Teitchou and 3 more

Journal of Geological Research

Mount Cameroon is a Plio-Quaternary volcanic massif, without a centralcrater, made up of more than 140 pyroclastic cones. It is one of theactive volcanoes of the Cameroon Volcanic Line. Mount Cameroon meltinclusions are found in microdroplets trapped in the early minerals (olivines)from the pyroclastic products. The analysis of these melt inclusions allowedus to find primitive liquids compared to lavas. Major elements study ofthe magmatic inclusions, trapped in the most magnesian olivines (Mg#84-86) of Mount Cameroon revealed “primitive” liquids of basanite and alkalibasalt type with variable composition compared to the much more uniformbasalts of the magmatic series of Mount Cameroon. The study of thesetrapped liquids shows that: (1) the original primitive lavas did not undergothe process of evolution by FC, but rather underwent fundamentally (orexclusively) the process of partial melting; (2) the emitted lavas, evolvedessentially by FC; (3) the variations in the trace element contents of theprimitive liquids directly reflect a variation in the rate of partial melting ofa homogeneous mantelic source. The very high La/Yb ratios of the MountCameroon melt inclusions (> 20) characterize a garnet lherzolite source.Spectra of the melt inclusions show a negative anomaly or depletion in K,Rb and Ba as those of HIMU. The “primitive” liquids and lavas of MountCameroon represent a co-genetic sequence formed by varying degrees ofpartial melting of a source considered as homogeneous.

• #geological and geochemical analysis
• #geochemistry and geologic mapping
• #high-pressure geophysics and materials
• #melt inclusions

Application of Remote Sensing for the Mapping of Geological Structures in Rainforest Area: A Case Study at the Matomb-Makak Area, Center-South Cameroon

Victor Metang, Charles Nkoumbou, Tchakounté Numbem Jacqueline, Daniel Njopwouo

Journal of Geosciences and Geomatics

In the areas with rainforest vegetation, the use of SRTM (Shuttle Radar topography Mission) data because of their penetrative characters, high quality and availability, offers a new approach for the detection and interpretation of the geological structures. This paper presents the new structural mapping results of the Matomb-Makak area (western part of the Pan-African Yaounde series), based on the combined field survey and satellite image processing methods. The study area is characterized by dense forest vegetation with difficult access, scarcity and discontinuity of the available outcrops. As a consequence, geological mapping in this type of environment is difficult, time-consuming, expensive, and even dangerous and not accurate. During the field work, 280 outcrops have been investigated in which five main lithological units have been distinguished. In order to identify the foliation trajectories and the fractures network of kilometric scale, the techniques of remote sensing were used. The processing of SRTM data led to the detection of linear anomalies. These anomalies have been verified and validated to structural map on the basis of field data. The analysis of the structural map indicates: (1) two directions of S2 foliation (NE-SW major direction, locally folded and NW-SE secondary direction), (2) one family of faults trending NW-SE which locally displace the foliation, (3) a ductile shear zone with NNE-SSW trends which deflects the S2 foliation. The two directions of foliation observed in the Matomb-Makak area as well as the NW-SE direction of fault are similar to those observed in the Yaounde series by other authors. However, the structural map obtained from the interpretation of field data is quite different to that obtained from remote sensing. We have noticed that the folding structures resulting from the interpretation of the field data are not observed on the structural map obtained from the interpretation of satellite image processing. Thus, the mapping of foliation trajectories in the rainforest area on the solely basis of the field measurements, is most of the time, an extrapolation which does not represent the structural architecture at regional scale. It is concluded that the combination of field-based mapping and remote sensing methods are useful tool for the mapping of geological structures within the densely vegetated regions of southern Cameroun.

• #geochemistry and geologic mapping
• #geological and geophysical studies
• #groundwater and watershed analysis
• #shuttle radar topography mission