Original paper

Petrology of microdiamond-bearing schists from the Torrox unit, Betic Cordillera, Spain

Ruiz Cruz, Maria Dolores; Sanz De Galdeano, Carlos

Abstract

Microdiamond inclusions in garnet have been identified in pre-Triassic schists of unknown age from the Torrox unit in the Alpujárride complex, Internal Zone of the Betic Cordillera, Spain. Prior to this, ultrahigh-pressure (UHP) phases have been identified in granulites and gneisses associated with peridotites in the western zone of the Cordillera and in the NW of the Rif Mountains. This new finding reveals that the UHP metamorphism affected a crustal sequence notably thicker than previously assumed. In contrast with granulites and gneisses, in which only the UHP event and the local thermal effect of the peridotite emplacement have been identified, schists record a complex poly-metamorphic history, which contrasts with previous interpretations based on an exclusively Alpine metamorphic scenario. In addition to the UHP event, the schists show clear signals of two later metamorphic events, recorded by several stages of garnet growth, by staurolite?andalusite parageneses, and by matrix micas. In this study the metamorphic sequence is established, but the timing of the different metamorphic events remains uncertain.

Keywords

betic cordilleradiamondgarnetschistsspainuhp metamorphism