Neotectonic intersection of the Aegean and Cyprus tectonic arcs: extensional and strike-slip faulting in the Isparta Angle, SW Turkey

The Isparta Angle and adjacent Antalya Bay areas constitute an important se gment of the eastern Mediterranean region, located at the intersection of t he southward-convex Aegean and Cyprus arcs. Some recent tectonic maps show the Isparta Angle as a NW-SE compressional lineament extending eastwards in to the Kyrenia Range of northern Cyprus. However, fault data from the onsho re Isparta Angle, together with offshore shallow seismic reflection data, s how that the present morpho-tectonic setting is dominated by extension. The last phase of compression to affect the area studied in the Late Miocene, was accompanied by regional nappe emplacement (Lycian Nappes). Onshore, fau lt planes, measured from fault zones bounding both the limbs and the core o f the Isparta Angle are oriented predominantly NE-SW, NW-SE and N-S. Superi mposed slickenfibres show that reverse faults were succeeded, in turn, by r ight-lateral faults, then by normal faults. The fault phases are dated by s tratigraphical and geomorphological evidence. Reverse faults date from the Late Miocene, or earlier compressional deformation, whereas the right-later al faults mainly developed during latest Miocene-Early Pliocene. Normal fau lting dominated from the Late Pliocene-Recent. An interpretation of shallow seismic reflection data shows that Antalya Bay is characterised by a NW-SE -trending asymmetrical graben system that has continued to be active. Durin g the Late Miocene-Early Pliocene right-lateral strike-slip resulted from s heer along the eastern termination of a zone of extension and rotation that characterises the western Aegean. This shear was focused in a N-S directio n by inherited zones of structural weakness in the basement (Antalya Comple x). The switch to NE-SW extension in the Late Pliocene-Quaternary relates t o a regional change in stress direction throughout the Aegean region and wa s accompanied by strong uplift of the Bey Daglari region of the Taurus Moun tains, bordering the Isparta Angle in the west. The Isparta Angle is the li nk between: (a) the extensional province of western Turkey bounded to the s outh by the actively subducting Hellenic are; and (b) the uplifted Anatolia n plateau bounded to the south by the Cyprus subduction zone. Understanding the Miocene to Recent tectonic development helps elucidate the kinematics of the region. The new structural data presented lend no support for recent suggestions that the Isparta Angle and Antalya Bay represent parts of a re gional compressional zone related to plate collision. (C) 1998 Elsevier Sci ence B.V. All rights reserved.