Middle Miocene high-pressure metamorphism and fast exhumation of the Nevado-Filabride Complex, SE Spain

Abstract

This study provides new constraints on fast cooling and exhumation rates of high-pressure metamorphic rocks in young active mountain belts. Ion microprobe (SHRIMP) U-Pb analysis of zircon in a pyroxenite layer of the Cerro del Almirez ultramafic rocks (Nevado-Filábride Complex, southern Spain) gave an age of 15.0 ± 0.6 Myr (95% c.l.). Mineral inclusions demonstrate that zircon formed close to the high-pressure peak. Combined with previous fission track data, the 15 Myr age suggests high cooling (~ 80 °C Myr-1) and exhumation (~ 1.2 cm yr-1) rates for the unit. The new results indicate that both the Nevado- Filábride Complex and the overlying Alpujárride Complex, with somewhat higher ages and exhumation rates, underwent similar metamorphic evolutions at different times. This implies that the Alpujárride rocks were exhumed when the Nevado-Filábride was subducting and that the same tectonic scenario propagated from one portion of the Betic Cordilleras to another.