Cooling history of the Chapedony metamorphic core complex, Central Iran: Implications for the Eurasia-Arabia collision

New apatite and zircon (U-Th)/He thermochronometry is used to constrain the late-stage cooling history of the Chapedony metamorphic core complex in the Saghand region of Central Iran, providing new constraints on the Cenozoic tectonic evolution of this segment of the Euro-Arabian collision zone. Zircon and apatite He ages from the footwall indicate that it cooled to near-surface temperatures by 30 Ma. Combined with previous high temperature thermochronology, the new data require that the Chapedony metamorphic core complex cooled from similar to 750 degrees C to similar to 60 degrees C in less than 20 million years (at similar to 80 degrees C/Myr). Cooling of the complex occurred through tectonic exhumation at a rate of 12-1.5 km/Myr. Exhumation of the core complex occurred during the main phase of subduction of the distal Arabian margin beneath the Central Iranian Plate at 49 to 30 Ma. Zircon He ages from the hangingwall units of the complex suggest an earlier pulse of exhumation in Middle-Late Cretaceous. Apatite He ages from the hangingwall (22-30 Ma) are significantly younger than the core complex exhumation but is consistent with the regional timing of initial Eurasia-Arabia collision. (C) 2011 Elsevier B.V. All rights reserved.