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 ultrarnafic rocks (Nevado-Filabride
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 (similar to 80 degreesC Myr(-1)) and
exhumation (similar to 1.2 cm yr(-1)) rates for the unit. The new
results indicate that both the Nevado-Filabride Complex and the
overlying Alpujarride Complex, with somewhat higher ages and exhumation
rates, underwent similar metamorphic evolutions at different times.
This implies that the Alpujarride rocks were exhumed when the
Nevado-Filabride was subducting and that the same tectonic scenario
propagated from one portion of the Betic Cordilleras to another.