A suture related accretionary wedge in the Gondwana assembly: Insights from serpentinites in the Hoggar shield, Algeria

The assembly of West Gondwana supercontinent involved several complex processes that led to the formation Hoggar shield during Panafrican-Brasiliano event. We present first petro-geochemical, geochronological and field data serpentinite lenses exposed along In-Tedeini domain, within deformed talc-schist magmatic-sedimentary formations. serpentinites preserved main characteristics their parent peridotites (Al/Si: 0.004–0.03; Mg/Si: 1.14–1.62; Al2O3: 0.15–1.37 wt%; Mg#: 85.3–94; Ti: 9.34–120 ppm; Nb: 0.007–0.46 ppm), attesting a highly depleted mantle wedge protolith in subduction zone. This is agreement with high Cr# (0.55–0.6), low moderate Mg# (0.36–0.65) TiO2 contents (<0.1 wt%) constitutive Cr-spinels. Geochemical modelling suggest both North South units have experienced intense similar fluid-induced dynamic melting episodes. evolution these two has diverged, Southern unit being refertilized by small volume island-arc basaltic melts generated wedge. Serpentinization rocks probably occurred under static conditions at temperature corresponding essentially amphibolite-facies conditions. Field relations exhumation massive major sinistral shear zones steeply dipping eastward, assisted talc-schists localized transpressive deformation. First U-Pb zircon ages obtained from metasomatic chloritite serpentinites; they may recorded age (770 ± 5 Ma) related Panafrican island arcs emplacement (631 10 crust; or rather correspond serpentinization events endured rocks. All together, reported results support presence suture zone, oriented NNW-SSE. outlined exhumed collisional accretionary wedge, which connects western central Hoggar, following east-dipping subduction. tectonic system would contributed closure Goiás-Pharusian ocean.