Constraints on the kinematics of post-orogenic extension imposed by stretching lineations in the Aegean region

New kinematic data from shear zones of Tertiary age in the metamorphosed ba sement of the Aegean region, in combination with published kinematic, litho logical and palaeomagnetic data, have enabled us to determine a detailed ki nematic evolution of the region during post-orogenic extension in the Aegea n. Three distinct stages are recognised. Firstly, extension of both the wes tern and eastern Aegean started in the Late Oligocene-Early Miocene (simila r to 36-25 Ma ago), initially in an similar to 023 degrees direction. Stage two started shortly after this with the division of the Aegean crust into the West Aegean Block (a coupled assemblage of small blocks) bound on its n orthwestern and southeastern margins by the Scutari-Pec Line and Mid-Cyclad ic Lineament (fracture zones), respectively. Between 25 Ma and similar to 3 Ma the West Aegean Block underwent similar to 30 degrees clockwise rotatio n, whilst the eastern Aegean underwent, on average, similar to 19 degrees a nticlockwise rotation. Rotation of the West Aegean Block as a semi-coherent block was aided by the relative 'coolness' of the block compared to the 'w armer' eastern Aegean region. As the crust thinned and rotated, the NW-SE-t rending faults which characterise the West Aegean Block were cross-cut by E -W-trending faults. Ln the latest Miocene-Pliocene, the thermal front migra ted westwards into the West Aegean Block and the Mid-Cycladic Lineament cea sed activity. The final kinematic stage marked the start of the subdivision of the West Aegean Block into two portions in the Pliocene. The southeaste rn portion (NW Cycladic area) coupled with the SW Cycladic area to form a C entral Aegean Block that started to translate southwest. The northern and w estern portion rotated a further similar to 10-15 degrees clockwise whilst the southeastern rim rotated anticlockwise. These data demonstrate that Aeg ean post-orogenic extension is not dominated by a single block rotation or radial spreading event, but is characterised by the sequential formation an d reformation of lithospheric-scale blocks that have developed in response to large-scale partitioning of rotational strain. (C) 1998 Elsevier Science B.V. All rights reserved.