| Early exhumation of high-pressure rocks in extrusion wedges: Cycladic blueschist unit in the eastern Aegean, Greece, and Turkey Auteur(s) : Ring, U. Will, T. Glodny, J. Kumerics, C. Gessner, K. Thomson, S. Gungor, T. Monie, Patrick Auteurs secondaires : Department of Geological Sciences, Canterbury University, Christchurch ; Université du Québec Institut für Mineralogie, Universität Würzburg ; Universität Würzburg GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ) Institut für Geowissenschaften, Johannes Gutenberg-Universität, Mainz ; Johannes Gutenberg Universitat Mainz School of Earth and Geographical Sciences, University of Western Australia, Crawley ; Université du Québec Department of Geology and Geophyiscs, Yale University, New Haven ; Université du Québec Jeoloji Mühendisligi Bölümü, Dokuz Eylül Üniversitesi, Bornova ; Université du Québec Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Éditeur(s) : HAL CCSD American Geophysical Union (AGU) Résumé : Structural, metamorphic, and geochronologic work shows that the Ampelos/Dilek nappe of the Cycladic blueschist unit in the eastern Aegean constitutes a wedge of high-pressure rocks extruded during early stages of orogeny. The extrusion wedge formed during the incipient collision of the Anatolian microcontinent with Eurasia when subduction and deep underthrusting ceased and the Ampelos/Dilek nappe was thrust southward over the greenschist-facies Menderes nappes along its lower tectonic contact, the Cycladic-Menderes thrust, effectively cutting out a ∼30- to 40-km-thick section of crust. The upper contact of the Ampelos/Dilek extrusion wedge is the top-to-the-NE Selçuk normal shear zone, along which the Ampelos/Dilek nappe was exhumed by ∼3040 km. Detailed Rb-Sr and 40Ar/39Ar dating of mylonites demonstrates that both shear zones operated between 42 and 32 Ma. There is no evidence for episodic motion during the ∼10 Myr life span of the shear zones, suggesting that both shear zones operated in a steady, nonepisodic fashion. Our data provide supporting evidence that simultaneous thrust-type and normal sense shearing can accomplish the early exhumation of deep-seated rocks ISSN: 0278-7407 hal-00405013 https://hal.archives-ouvertes.fr/hal-00405013 DOI : 10.1029/2005TC001872 | Partager
|