Clockwise, low- metamorphism of the Aus granulite terrain, southern Namibia, during the Mesoproterozoic Namaqua Orogeny

2013

Abstract The Aus granulite terrain forms part of the Mesoproterozoic Namaqua Metamorphic Complex (NMC) of southern Africa. The terrain consists of pre- to syn-tectonic granitoid gneisses containing subordinate aluminous metasediments, metapsammites, mafic granulite and calc-silicate, all of which have been metamorphosed and migmatised to varying degrees. Pseudosection modelling of garnet–sillimanite–cordierite–biotite aluminous metapelitic samples constrain peak metamorphic conditions at 5.5 kbar and 825  ° C. Pseudomorphs of sillimanite after andalusite constrain early prograde conditions of ∼ 550–600  ° C at below 4 kbar, whereas the replacement of sillimanite by garnet–cordierite and sub…