Geology of the northern side of the Gulf of Edremit and its tectonic significance for the development of the Aegean grabens

Abstract

This paper describes the Neogene evolution of north-Western Anatolia based on geological data collected in the course of a new mapping program. The geological history of the region, as recorded by the Neogene sedimentary and magmatic rocks that overlie the Paleozoic-Triassic basement, began after a lake invasion during the Early Miocene period with the deposition of shale-dominated successions. They were accompanied by calc-alkaline intermediate lavas and pyroclastic rocks ejected through NNE trending fractures and faults. The Lower-Middle Miocene successions were deformed under a compressional regime at the end of the Middle Miocene. The deposition of the overlying Upper Miocene-Lower Pliocene successions was restricted to within NE-SW trending graben basins. The graben bounding faults are oblique with a major strike-slip displacement, formed under approximately the N-S extension. The morphological irregularities formed during the Miocene graben formations were obliterated during a severe erosional phase to the end of the deposition of this lacustrine succession. The present E–W graben system as exemplified from the well-developed Edremit graben, postdates the erosional phase, which has formed during the Plio-Quaternary period. © 2001 Éditions Scientifiques et médicates Elsevier SAS