Maps of the paleography of Iran are presented to summarize and review the geological evolution of the Iranian region since late Precambrian time. On the basis of the data presented in this way reconstructions of the region have been prepared that take account of the known major movements of continental masses. These reconstructions, which appear at the beginning of the paper, show some striking features, many of which were poorly appreciated previously in the evolution of the region. They include the closing of the 'Hercynian Ocean' by the northward motion of the Central Iranian continental fragment(s), the apparently simultaneous opening of a new ocean ('the High-Zagros Alpine Ocean') south of Iran, and the formation of 'small rift zones of oceanic character' together with the attenuation of continental crust in Central Iran.With the disappearance of the Hercynian Ocean, the floor of the High-Zagros Alpine Ocean started to subduct beneath southern Central Iran and apparently disappeared by Late Cretaceous – Early Paleocene time (65 Ma). From this time the compressional motion between Arabia and Eurasia has been accommodated in Iran by shortening and thickening of the continental crust. This crustal thickening is accompanied by a progressive, though eventful, transition from marine to continental conditions over the whole region.A striking feature highlighted in this study is the existence of extensive alkaline and calc-alkaline volcanics, which appear to be unrelated to subduction. The intrusion of these rocks started in Middle Eocene time (45 Ma) and extended to the present. It is clear that some major fault systems have played a continuous but varied role from the Precambrian until the present, and whatever controlled the original fold orientation at the onset of continental compression (65 Ma) apparently still controls the orientation of contemporary folding.

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...

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Between 1939 and 1999 the North Anatolian fault (NAF) experienced a westward progression of eight large earthquakes over 800 km of its morphological trace. The 2000‐km‐long North Anatolian transform fault has also grown by westward propagation through continental lithosphere over a much longer timescale (∼10 Myr). The Sea of Marmara is a large pull‐apart that appears to have been a geometrical/mechanical obstacle encountered by the NAF during its propagation. The present paper focuses on new high‐resolution data on the submarine fault system that forms a smaller pull‐apart beneath the Northern Sea of Marmara, between two well‐known strike‐slip faults on land (Izmit and Ganos faults). The outstandingly clear submarine morphology reveals a segmented fault system including pull‐apart features at a range of scales, which indicate a dominant transtensional tectonic regime. There is no evidence for a single, continuous, purely strike‐slip fault. This result is critical to understanding of the seismic behaviour of this region of the NAF, close to Istanbul. Additionally, morphological and geological evidence is found for a stable kinematics consistent both with the long‐term displacement field determined for the past 5 Myr and with present‐day Anatolia/Eurasia motion determined with GPS. However, within the Sea of Marmara region the fault kinematics involves asymmetric slip partitioning that appears to have extended throughout the evolution of the pull‐apart. The loading associated with the westward propagation process of the NAF may have provided a favourable initial geometry for such a slip separation.