Quaternary neotectonics of the South Aegean arc

Abstract

The sedimentary and tectonic Quaternary evolution of the South Aegean arc has been interpreted from 8000 line-km of sparker seismic reflection profiles. The older parts of basins formed by E–W-trending faults and accumulated hemipelagic sediment. Younger active faulting trends NNW in the western part of the arc and ENE in the eastern arc. The ENE-trending faults record sinistral strike-slip motion broadly parallel to the convergence direction of the Aegean–Anatolian and African plates. The north–south faults in the western arc are similar to those on land in the south Peloponnese. Chronology is estimated from sedimentation rates in cores and from stacked progradational units on basin margins controlled by eustatic changes in sea level. The younger fault pattern developed at 0.6–0.8 Ma in the western and central arc, but progressively younger in the southeastern part of the arc. The older basin fill with E–W faults is of early Quaternary and Pliocene age. An older regional unconformity corresponds to an early Pleistocene unconformity in the Cretan basin. Particularly in the area east of Santorini, faulting has resulted in startling changes in palaeogeography, such that some areas were late Pliocene basins, positive features during the Pleistocene and then subsided 600 m in the last 0.2 Ma. Such rapid basin inversion resulted in uplift of stratified hemipelagic muds, which were deformed by creep or failure, so that debris flow deposits accumulated in valleys and ponded basins. These fundamental tectonic changes in the past two million years indicate that much of the deformation resulting from the interaction of the Eurasian, African and Anatolian–Aegean plates is taken up at the southern margin of the Aegean microplate, probably because subduction of the African plate has slowed as a result of collision of continental crust. Regional fault patterns are a consequence of spatially varying effects of subduction roll-back.