A subducted Neoproterozoic rift assemblage: The Egere Group (central Hoggar, Algeria)

摘要: Abstract The metasedimentary Egere Group (central Hoggar, Algeria) mainly comprises abundant marbles, metapelites, metaquartzites and mafic rocks, all affected by eclogitic metamorphism. Field relationships pre-metamorphic features in the northern region attest that most eclogites represent basaltic metatufs, metabasalts extruded during carbonate sedimentation sills. A slice of ultramafic rocks includes polymictic sedimentary breccias containing blocks marble, suggesting these a preserved piece ocean-continent transition. observations, along with published metamorphic constraints age determinations suggest was deposited Neoproterozoic rift zone. Following peak metamorphism (T = from 700 to 770 °C P max. around 19 kbar after Doukkari et al., 2014), anatexis at decreasing pressure. Strong high-temperature ductile deformations, NW-verging folds thrustings relate exhumation lower crust assisted viscous flow anatectic domes. location similar pre-tectonic calc-alkaline plutons exposed west 4°50 fault Iskel terrane formed west-dipping subduction setting.