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Granites are widespread in many Precambrian orogenic belts worldwide; therefore, they can provide insights into orogenic processes and associated magmatism. Zircon U Pb age, monazite Th-U-total Pb age and whole-rock geochemical data for a granite pluton from the Gari-Gombo area in the Adamawa-Yade domain of the Central African Fold Belt (CAFB) in East Cameroon are presented. The granite is composed dominantly of perthitic K-feldspars, quartz, plagioclase and minor biotite with accessory monazite, apatite and zircon. LA-ICP-MS zircon U Pb dating yielded an age at ca 631–620 Ma, which is interpreted as age of emplacement that coincides with the onset of D2 Pan-African deformation. Monazite grains in Gari-Gombo granite follow strictly the huttonite substitution trend in Th + U vs Si coordinates. Monazites give consistent Neoproterozoic ages of 630 ± 4 Ma and 602 ± 4 Ma, indicating that growth history and crystallization age of monazites also correlate well with the Pan-African plutonism and granulite facies metamorphism (ca 614–600 Ma) in the Gari-Gombo area. The Gari-Gombo pluton samples show high-K calc-alkaline magnesian, slightly peraluminous signature, high SiO 2 (70.16–78.80 wt%), K 2 O (4.39–5.38 wt%), and Rb (165–248 ppm), and low P 2 O 5 ≤ 0.01 wt% and Sr (146–222 ppm) contents. They have highly-fractionated REE pattern ((La/Yb) N = 6.17–148.18), moderately Eu negative anomalies (Eu/Eu* = 0.53–0.93) and the obviously Nb and Ti negative anomalies. These geochemical features suggest that the Gari-Gombo pluton is a highly fractionated I-type granite generated by partial melting of older meta-igneous materials at middle to lower crustal levels. The 2.9 and 0.95 Ga inherited zircon grains identified within the studied granites further confirm the existence of ancient crust in this region. • The ca 631– 620 Ma Gari-Gombo pluton emplaced during the D2 regional Pan-African deformation. • Gari-Gombo pluton intrusive granites represent highly fractionated I-type granite generated by partial melting of partial melting of 2.9 Ga meta-igneous rocks. • EPMA U-Th-Pb monazite dating of the Gari-Gombo granite yields metamophic recrystallization ages of 602 ± Ma. [ABSTRACT FROM AUTHOR]

Though Yaoundé zone is characterized by abundant rains, access to safe drinking water becomes a difficult activity, because of climate change and pollution caused by human activities. Lineament zones on the earth’s surface are important elements in understanding the dynamics of the subsurface fluid flow. However, good exposures of these features are always lacking in some areas around Yaoundé, characterized by thick alteration. During field surveys these conditions, in many cases, hinder the proper characterization of such features. Therefore, an approach that identifies the regional lineaments on remote-sensing images (Landsat Thematic Mapper and shaded digital terrain models), with its large scale synoptic coverage, could be promising. This paper aims to the structural organization of lineament network in the crystalline basement of Yaoundé from remote sensing data and characterize them by statistical and geostatistical techniques. The results were validated on the basis of the geological maps, the hydrogeological maps and the outcrop data. Statistical analysis of the lineaments network shows a distribution along the N0–10, N20–30, N40–60 and N140–150. The correlation between the productivity of high yield wells and the closest lineament confirms that these lineaments are surface traces of regional discontinuities and act as main groundwater flow paths. [ABSTRACT FROM AUTHOR]

Electron microprobe (EPMA) monazite Th–U – Pb ages have been determined from a suite of granulite and granitoids rocks of the Sangmelima granite-greenstone Belt (SGB) of the Ntem Complex in Cameroon or NW Congo Craton. The monazite-bearing rocks include charnockitic gneiss, migmatitic tonalite-trondhjemite-granodiorite (TTG) gneisses, granodiorite, monzogranite and a late pegmatite intrusion. The monazites of Sangmelima can be classified as monazite-Ce. Based on published ages and EPMA Th–U – Pb monazite age data from the SGB, the geodynamic evolution of the NW Congo Craton was refined through its tectonometamorphic and magmatic events. The major charnockitic and TTG magmatism event in Ntem Complex occurred between ~2950 and 2850 Ma. This Mesoarchean crystalline basement underwent two major ductile tectonothermal events M 1 – D 1 and M 2 – D 2. (1) The onset of M 1 – D 1 corresponds to the migmatization of TTG at 2843 Ma coeval with the emplacement of syn-kinematic granite dykes (monzogranites) at 2840–2825 Ma. The S 1 regional penetrative foliation (D 1) was progressively generated during the M 1 metamorphic event, which led to the formation of associated hypersthene-garnet-bearing granulitic mineral assemblage that peaked at ~2830 Ma. (2) The M 2 – D 2 event between 2760 and 2740 Ma corresponds to the folding of S 1 regional foliation by F 2 folds and development of C 2 shear zones synchronous with the anatexis event that generated the high-K granitoids at 2750 Ma. Late Neoarchean granitic pegmatite/aplite dikes and/or veins emplaced during the brittle deformation D 3 and protracted cooling of the Ntem Complex between ~2700 and 2550 Ma. Our new EPMA monazite U–Th – Pb ages from the SGB highlight similar magmatic and tectonothermal events of the adjacent northern Gabonese domain and the Chaillu Massif in Gabon part of the NW Congo craton (ca. 3.0–2.5 Ga). • Major crustal accretion event in the NW Congo Craton between 2.95 and 2.85 Ga. • Long-lasting Archean deformation history characterized by two major tectonothermal events at 2.84–2.82 Ga and 2.76–2.74 Ga. • CHIME-EPMA U-Th- total Pb monazite dating for Archean rocks. [ABSTRACT FROM AUTHOR]

Structural study of in the Sangmelima granite-greenstone terrains (SGB) provide a new overview of the evolution of the Ntem Complex (South Cameroon), the northwestern part of the Congo Craton. The regional deformation is marked by a strong steep dips foliation and steeply plunging mineral-stretching. D 1 -related structures are folding and shearing by a D 2 deformation that is synchronous with extraction granitic dykes. D 1 –D 2 structures were developed during regional E-W sub-horizontal shortening under ductile conditions associated with steeply dipping principal stretching in a transpressive regime, progressive strain localization along strike-slip shear zones. Syn-D 1 mineral assemblages and high strain microstructures suggest that ductile deformation D 1 occurred under high-grade metamorphic conditions, whereas D 2 microstructures suggest a brittle deformation. The strain patterns in the SGB recorded a long-lasting Archean tectonic history within the Archean Ntem Complex (ca. 2.83–2.72Ga). Finally, some Archean structures were reactivated during a brittle deformation (D 3), likely during the Eburnean event. • This paper present a new overview of the tectonic model in the Ntem Complex (South Cameroon), Congo Craton. • D 1 regional horizontal shortening is associated with high-grade metamorphism and partial melting. • D 2 transpressional deformation coeval with extraction granitic dykes. • D 1 -D 2 structures suggest a long-lasting progressive Archean deformation in Ntem Complex. [ABSTRACT FROM AUTHOR]