Abstract

New fission-track thermochronologic data from the high-pressure (P)–low-temperature (T) rocks of Crete, Greece, combined with pressure, temperature, and stratigraphic constraints reveal that their subduction began between 36 and 29 Ma. Metamorphism took place in western Crete at peak conditions of 10 ± 2 kbar and 400 ± 50 °C between 24 and 19 Ma, and rapid exhumation to <10 km and <300 °C at a minimum rate of 4 km/m.y. was completed before 19 Ma. Constraints from the thermal history of the plate above the inferred extensional detachment reveal that tectonic unroofing contributed 85% to 90% of the overall exhumation of the high-P–low-T rocks of Crete. We propose that the Hellenic subduction zone has acted as a retreating plate boundary since at least the early Oligocene, and collision and extension during this time were driven by roll-back associated with slab-pull rather than by gravitational collapse as a consequence of crustal thickening. The speed of subduction and exhumation of the high-P–low-T rocks of Crete within ∼10 m.y. has important implications for other orogenic belts, showing that rocks can be subducted, metamorphosed at high pressure, and exhumed, despite slow overall plate convergence, within the uncertainties of many paleontologic and isotopic age data.

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