Syn- and post-orogenic exhumation of metamorphic rocks in North Aegean
29 Nov 2007
1Institut de Physique du Globe de Paris, UMR7174 CNRS, Paris, France
2Lab. Dynamique de la Lithosphère, UMR 5573 CNRS, USTL, Montpellier, France
3Lab. Sciences de la Terre, UMR5570 CNRS, UCB Lyon, France
4Lab. Tectonique, UMR7072 CNRS, Univ. P. et M. Curie, Paris, France
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). Structural 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 normal faulting with northeastward transport, is coeval with orogenic shortening in the close area. Cooling rates, and likely exhumation, have been low between ~40 Ma and ~20 Ma. 40Ar/39Ar crystallization ages (between 20 and 15 Ma) appears related to brittle-ductile normal faulting and likely associated with Neogene Aegean back-arc extension. The dating 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.