Skip to Main content Skip to Navigation
New interface

La zone de cisaillement de Kandi et le magmatisme associé dans la région de Savalou-Dassa (Bénin) : étude structurale, pétrologique et géochronologique

Abstract : The present study focuses on the structural characteristics of the Kandi shear zone (KSZ) and the time and space relationships between deformation and magmatic events in the central region of Bénin. This tectonic structure is a segment of a lithospheric-scale shear zone that extends from the Hoggar massif (Algeria) to the Atlantic Coast in Bénin and continues down to western Brazil. The present work aims at better understanding the late to post-collision geodynamic evolution of the pan African Dahomeyide fold beltIn summary, this study reveals that the Kandi shear zone in the Central-Bénin is a large (more than 50 km width) dextral transcurrent shear zone, where the latest increments of deformation occur as more localized (kilometric-scale width) shear bands at low temperature. The KSZ activity started at c. 610 Ma and affected the rock basement, including Paleoproterozoic granulites and Neoproterozoic gneisses, migmatites and granitoids. The granitoids intrusions that are spatially associated to the KSZ display ante- to syn-shearing structural features. The earliest intrusion, ante-tectonic Dassa has sub-alkaline affinity deriving from crustal and depleted mantle magmas. This sub-alkaline series carry on during the transcurrent shearing with the Gobada, Tré, Tchetti intrusions. The latest magmatic event of Fita intrusion suggests the transition from sub-alkaline to alkaline magmas, probably reflecting mantle source evolution, from depleted to enriched mantle. We also showed that the Idaho-Mahou volcano-sedimentary basin opened during the transcurrent shearing and the volcanic mafic and felsic rocks are probably related to the successive sub-alkaline to alkaline intrusions. The occurrence of mantle-derived magmas in the shear zone confirms the lithospheric scale of the Kandi shear zone. According to the available radiometric data from the Dahomeyides fold belt, the Kandi shear zone activity seems to contemporaneous with the nappes stacking and thrusting stages in the external orogenic zone (Atacora and western Benin plain) orogen-scale. It also indicates that the KSZ was coeval with the major shear zones from the easternmost region of the Dahomeyides fold belt (NE Nigeria), of the Hoggar and Braziliano belts.
Document type :
Complete list of metadata

Cited literature [148 references]  Display  Hide  Download
Contributor : ABES STAR :  Contact
Submitted on : Tuesday, February 25, 2014 - 10:42:10 AM
Last modification on : Tuesday, October 19, 2021 - 6:59:06 PM
Long-term archiving on: : Sunday, May 25, 2014 - 11:10:29 AM


Version validated by the jury (STAR)


  • HAL Id : tel-00951647, version 1


Luc Adissin Glodji. La zone de cisaillement de Kandi et le magmatisme associé dans la région de Savalou-Dassa (Bénin) : étude structurale, pétrologique et géochronologique. Sciences de la Terre. Université Jean Monnet - Saint-Etienne; Université d'Abomey-Calavi (Bénin), 2012. Français. ⟨NNT : 2012STET4001⟩. ⟨tel-00951647⟩



Record views


Files downloads