Discovery of granulite in the Mianxian-Lueyang suture zone, Mianxian area and its tectonic significance

Abstract

Mafic granulite lithoblocks, found at many localities near Xujiaping Village of Caimahe Town in Mianxian Coun-ty , occur in Mian-Lue suture zone as a lithoblock. Its metamorphic mineral assemblage is Cpx + Gt + PKAn30)+Qz + Rut. Temperature is between 657∗C and 772∗C calculated by thermometer of Ellis et al. Pressure ranges from 0. 82 GPa to 1. 17 GPa based on barometer by Newton et al. . Corrected values are respectively 0. 97 GPa and 1. 32 GPa. In thin-section, retrograde reaction in the mafic granulite is observed as Gt + Cpx = Hb + Pl. This reflects clockwise P-T-t path and metamorphic process with isothermal decompression, indicating collisional histroy along Mian-Lue suture zone of Qinling orogen.