Quaternary evolution of the Corinth Rift and its implications for the Late Cenozoic evolution of the Aegean

Abstract

International audienceWe present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active Aegean region. We focus first on the 130 km long Corinth Rift, an asymmetric graben where a flight of terraces of marine origin are uplifted. We show that the edges of the terraces lie in the footwall of the normal fault bounding the Corinth Rift and correspond to sea-level highstands of late Pleistocene age. Using a detailed analysis of aerial and SPOT imagery supported by field observations, we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault. The elevation of the terraces' inner edges was estimated at 172 sites with an error of + 5 m. This data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level. To date the deformation, we correlate the Corinth terraces with late Pleistocene oxygen-isotope stages of high sea-level stands and with global sea-level fluctuations. Using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary-element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault. We show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000. All the terraces are fitted for fault slip increasing in proportion to terrace age, and the component of regional uplift is found to be less than 0.3 mm yr-'. The best fits give a slip rate of 11 f 3 mm yr-' on the main rift-bounding fault over the last 350 kyr. Other geological and morphologic information allows us to estimate the total age of the main fault (z 1 Ma) and to examine the mechanical evolution of the Corinth Rift. The minimum observed sediment thickness in the Gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6-7 mm yr-' (40 per cent less than estimated with modelling). Even this slip rate is nearly 10 times higher than for comparable features in most of the Aegean and elsewhere in the world. At a larger scale, the spacing and asymmetry of the rift systems in the Aegean suggest strain localization in the upper mantle, with slow extension starting 15 Myr ago or earlier. The more recent (1 Myr), rapid phase of rifting in Corinth partly reactivated this earlier phase of extension. The younger faulting in Corinth appears to result from its present location in the inhomogeneous stress field (process zone) of the south-westward propagating tip of the southern branch of the North Anatolian Fault. We extend these relations to propose a mechanical model for the Late Cenozoic evolution of the Aegean. As the Arabia/Europe collision progressed in eastern Turkey it caused Anatolia to move to the west and the North Anatolian Fault to propagate into the Aegean, where the early slow extension star...

Kinematic reconstructions and magmatic evolution illuminating crustal and mantle dynamics of the eastern Mediterranean region since the late Cretaceous

“…Finally, additional extensional basins opened in the Peloponnese and along the eastern coast of the Hellenides, within the so-called Central Hellenides Shear Zone [Papanikolaou and Royden, 2007;Royden and Papanikolaou, 2011]. These basins include the Gulf of Corinth, which has accommodated ~15 km of N-S extension since the Pliocene (figure 3) [Armijo et al, 1996;Rohais et al, 2007;Jolivet et al, 2010b].…”

“…At the same time, extension ceased in the Cyclades and has localized at the edges of the Aegean domain, where highangle normal faulting has formed several grabens and half-grabens (figures 8w-y), such as in the Evvia island and the Corinth region (forming the Central Hellenic Shear Zone [Papanikolaou and Royden, 2007]), the Peloponnese, the Cretan Sea and the Menderes massif [Armijo et al, 1996;Royden and Papanikolaou, 2011;Pérouse et al, 2012]. This extensional tectonic regime has been accompanied in the Hellenides by a clockwise rotation of ~10° and ~23° north and south of the Central Hellenic Shear Zone [van Hinsbergen et al, 2005a;Bradley et al, 2013], increasing the curvature of the trench.…”

The role of elasticity in simulating long-term tectonic extension

“…King et al 1988;Weissel & Karner 1989;Armijo et al 1996;Schouten et al 2010). Further, the differences in rift morphology across spreading rates are generally well explained by rheological factors (i.e.…”

Crustal Strain in the Marmara Pull‐Apart Region Associated With the Propagation Process of the North Anatolian Fault

“…1a) [Armijo et al, 1999]. It has also been suggested that the propagating tip of the NAF reached the Corinth rift system in Greece around ~1 Ma [Armijo et al, 1996;Armijo et al, 1999]. Whether the westward propagation of the NAF is driven by the Arabia-Eurasia convergence and Anatolian block extrusion or by slab-pull mechanism associated with the Hellenic subduction zone (or by a combination of both processes) is subject of debate [e.g Armijo et al, 2003;Flérit et al, 2004;Sternai et al, 2014].…”

“…It is generally accepted that the NAF initiated at the Karlıova triple junction about ~10-13 Myrs ago [Şengör et al, 1985;Barka, 1992;Armijo et al, 1996;Armijo et al, 1999] and has grown by westward propagation over its nearly 2000 km-long trace (Fig. 1a) [Armijo et al, 1999].…”