Kinematic and thermal evolution during two‐stage exhumation of a Mediterranean subduction complex

We examine the kinematic and thermal evolution of the Nevado‐Filabride Complex (NFC), an Early to Middle Miocene subduction complex within the Betic Cordillera of southern Spain. Thermobarometry from the NFC in the Sierra Alhamilla reveals an inverted geothermal gradient, with peak temperatures and pressures of 560°C and 13 kbar reached in the uppermost tectonic unit. The NFC cooled during exhumation, defining a linear PT path that remained within the stability field of kyanite until the aluminosilicate breakdown reaction. Geo‐ and thermochronology suggest the NFC was subducted and exhumed to the surface within ∼10 m.y., recording an early stage of fast cooling from peak T through ∼250°C, followed by a late stage of slower cooling as the rocks approached the surface. The exhumation is associated with a progressive change in kinematics, with early co‐axial fabrics showing NNE‐SSW‐trending stretching lineations, and late non‐coaxial fabrics showing SSW‐trending lineations. A new tectonic model is proposed to explain these data, in which rocks at the leading edge of the Iberian margin were subducted southeastward beneath the thin, hot, Alboran lithosphere to form the NFC. The rocks at the top of the slab began to be exhumed once they reached 48–67 km depth. They were initially exhumed rapidly along the top of the subducting slab, in a subduction channel geometry; then upon reaching the middle crust, were captured by a low‐angle detachment fault with a WSW shear sense and final exhumation was accommodated more slowly in a core‐complex geometry.