Kinematics of conjugate shear zones, displacement partitioning and fragmentation of the upper rigid crust during denudation of high-P rocks (Pelagonian and Sub-Pelagonian Zones, Greece) A. Diamantopoulos a, ⁎, A. Krohe b , E. Mposkos a a National Technical University of Athens, School of Mining and Metallurgical Engineering, Division of Geological Sciences, Athens, Greece b University of Muenster, Institute of Mineralogy, Laboratory for Geochronology, Germany ABSTRACT ARTICLE INFO Article history: Received 28 April 2008 Accepted 28 May 2008 Available online 3 June 2008 Keywods: Non-coaxial strain Cataclastic flow Shear zones Kinematics Detachment Hellenides In the Sub-Pelagonian and Pelagonian Zones, kinematic analyses on faults and cataclastic shear zones document an overall displacement vector towards NNW and WSW/SSW for Attica and western Macedonia, respectively. This tectonic episode is interpreted as being triggered by the kinematically Oligocene–Miocene detachment of the Sub-Pelagonian and Pelagonian Zones from the high-P rocks. During this episode the Sub- Pelagonian and Pelagonian Zones were decoupled along detachment zones, fragmentised by brittle mechanisms and horizontally stretched in km-scale. The strain record of the cataclastically-deformed lithologies of the upper plates reveals a complex kinematic pattern with displacement partitioning in an overall non-coaxial regime. These structural processes are considered to be kinematically linked to the exhumation of the high-P rocks, deforming the Sub-Pelagonian and Pelagonian Zones. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Numerous studies pointed out that high-P rocks appear in the footwall of detachment faults formed during and after continental collision. Those detachments are frequently associated with the mechanical decoupling of the rigid upper plate from a plastically deforming lower plate (Wernicke and Burchfiel, 1982; Krohe and Mposkos, 2002; Jolivet et al., 2004; Brun and Sokoutis, 2007) that contain the high-P rocks. In the Hellenic orogen, metamorphic rocks of the Attic-Cycladic belt in the Olympos window and in Attica that experienced Eocene high-pressure (HP) metamorphism at the Moho depth lay in contiguous contact with rocks that stayed in the upper crust and deformed in a brittle manner. These brittely deformed rocks belonging to the Sub-Pelagonian and Pelagonian Zones are separated from the high-P rocks by systems of discrete detachment faults and form the upper plate of metamorphic core-complexes. The present article deals with two selected areas from the Internal Hellenides, the Sub-Pelagonian Zone in Attica and the Pelagonian Zone in western Macedonia (Kossmat, 1924; Brunn, 1956; Aubouin, 1973), Fig. 1 . In these areas, the Sub-Pelagonian and Pelagonian Zones constitute the upper plate of Cenozoic core complexes. While there are numerous kinematic and strain analyses of the high-P rocks of the lower plates that explain their exhumation paths, little attention has been paid to the mechanical and kinematic response of the upper plate during decoupling and displacement along the detachments. Particularly, it is still enigmatic which brittle-type deformational structures in the Pelagonian and Sub-Pelagonian Zones are kinema- tically related to displacements along detachments and to plastic deformation in the lower plate during exhumation of high-P rocks. In a general view, the finite geometry of the structures of the Pelagonian and Sub-Pelagonian Zones reflects successive deformation episodes during the last 10 Ma due to extension in the Aegean province (Brunn, 1976; Jacobshangen, 1977; Angelier, 1978). Kinematic and strain analyses from Attica and western Macedonia are presented in order to reveal the deformation partitioning of the different structures, the kinematic path and the displacement magnitudes in both areas. Well-exposed shear zones and fault rocks are studied in more than 250 different locations in the field. We point out the displacement vectors, the deformation intensity between the shear zones and in the different lithologies. A qualitative study of the finite and instantaneous strain (Turner and Weiss, 1963) was performed and strain distribution (Cowan et al., 2003) of the shear zones in all the scales were analysed. Moreover, it is shown that in both areas the deformation is kinematically linked with detachment of the upper plate from the lower plate's metamorphic rocks and occurred simultaneously in a uniform geodynamic domain. The complete structural scenario suggests that horizontal stretching and fragmentation of the upper plate is partitioned into different domains Tectonophysics 473 (2009) 84–98 ⁎ Corresponding author. Tel.: +30 210 7722069; fax: +30 210 7722126. E-mail addresses: diamantopoulos@metal.ntua.gr (A. Diamantopoulos), krohe@nwz-uni-muenster.de (A. Krohe), mposkos@metal.ntua.gr (E. Mposkos). 0040-1951/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2008.05.028 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto