Restraining bends in high temperature shear zones: The “Central Cameroon Shear Zone”, Central Africa

Neoproterozoic High-K Calc-Alkaline Granitoids from Bapa-Batié, North Equatorial Fold Belt, Central Cameroon: Petrogenesis and Geodynamic Significance

“…2.1Ga), (ii) dominance of metasedimentary sequences with Neoproterozoic deposition ages, (iii) ubiquitous presence of flat-lying structures of Neoproterozoic age (~650-600 Ma), and, (iv) dominance of transpressional/transcurent deformation After 600 Ma. The lack of evidence for closure of wide oceanic domains in all these regions does not support the interpretation of the central and south domains of the PANEFB as a series of amalgamated terranes [18]. Destabilisation of a pre-existing continent that formed at the end of Paleoproterozoic/Eburnean orogeny [67] provides the simplest explanation to the above findings.…”

“…These large NE-striking transcurent faults, as well as the Adamaoua Fault inside the central domain, are regarded as possible prolongations of the major shear zones of NE Brazil in a pre-drift Gondwana reconstruction [15][16][17][18]. This central domain consists of Paleoproterozoic high-grade gneisses (850-900°C, 1-1.2GPa) with Archean inheritance in the Palaeoproterozoic gneiss of Meiganga intruded by widespread Neoproterozoic syntectonic plutonic rocks of high-K calc-alkaline Affinities [4-6, 9, 19-24].…”

“…Conventional U-Pb zircon dating has yielded an age of 602 ± 1.4 Ma for this syntectonic Pan-African magmatism in the Batié area [26]. Some geochronological investigations have been carried out on some major magmatic complexes: the Ngondo granitic complex [19], Bandja charnockitic massif [18] and Bangwa granites [25] in the central domain; their emplacement ages vary from 557 ± 8 to 686 ± 17 Ma (Rb/Sr whole rock); an U-Pb zircon ages of 640 ± 15Ma and 638 ±2 Ma were obtained on the Bandja charnockite and Bangwa granite respectively. All these ages span the early stage of the deformation (orthogneisses) to the late uplift stages (post-tectonic massifs) of the Pan-African fold belt in Cameroon [9,11,19,26].…”

Evidence for the Upwelling of Mafic Bodies into the Upper Crust beneath the N40-50°E Branch of the Pan-African Central Cameroon Shear Zone from Gravity Studies

“…These gneisses are affected by NE striking ductile transcurrent/transpression shear zone known as Foumban-Foutoni shear zone [20] [21] [22] [23] which has controlled the emplacement of 610 to 570 Ma post-collision granitoids (leucogranites, granites, syenites) of high-K calc-alkaline, peraluminous and shoshonitic affinities [21] [24] [25].…”

“…The low anomaly observed may be due to the emplacement of the sheet-like granitoids reported in the area [22] [25] and volcanic low density products (pyroclastic materials) emitted through the Baleng Lake exposed in the area. The third low gravity anomaly area in Bangou, displays a NW-SE oriented which then curves into N20˚E and comes back to the NW-SE trend.…”