Spinel-quartz association in the Androyen granulite terrain in the southern part of Madagascar

Abstract

We examined petrological characteristics of the metapelites from the Androyen system, which occupies the eastern part of the terrain. It is composed of charnockite, leptynites, pyroxenite, granite and metapelites. This terrain is bounded by two major shear zones: to the north by the SW-SE trending Bongolava-Ranotsara shear zone and to the west by NS Betroka shear zone. In this study we mapped Spl-Qtz occurrences in the metapelites in strikingly wide areas extending over ∼200km. Spl-Qtz rocks are distributed along the two shear zones (Bongolava Ranotsara shear zone and Betroka shear zone). The Spl-Qtz metapelites probably represent the roots of the continental crust uplifted during the Pan African collision event.