Syn- and post-orogenic exhumation of metamorphic rocks in North Aegean

Abstract

Abstract. The Olympos-Ossa-Pelion (OOP) ranges, in NW Aegean, encompass Greece highest summit and are located near the extremity of the North Anatolian Fault (NAF). Struc- tural and thermochronological data gathered in the OOP ranges show that the main exhumation of metamorphic nappes occurred in the Eocene, at ca. 43–39 Ma. This early exhumation, associated with ductile, then brittle-ductile nor- mal faulting with northeastward transport, is coeval with oro- genic shortening in the close area. Cooling rates, and likely exhumation, have been low between ∼40Ma and ∼20 Ma. 40Ar/39Ar crystallization ages (between 20 and 15 Ma) ap- pears related to brittle-ductile normal faulting and likely as- sociated with Neogene Aegean back-arc extension. The dat- ing of a diabase dyke, and the geometry of associated brittle jointing, of onshore and offshore active normal faults suggest a shift in extension direction after 4Ma, possibly in relation with the propagation of the NAF in northern Aegean.