Neotectonic deformation in the western sector of tectonic escape in Anatolia: palaeomagnetic study of the Afyon region, central Turkey


Gursoy H. , Piper J., Tatar O.

TECTONOPHYSICS, cilt.374, ss.57-79, 2003 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

Following final closure of the Neotethyan Ocean during the late Miocene, deformation in central Turkey has led to crustal thickening and uplift to produce the Anatolian Plateau followed by westward extrusion of terranes by strike-slip. Widespread volcanism has accompanied this latter (neotectonic) phase, and palaeomagnetic study of the volcanism shows a coherent record of differential block rotations, indicating that the Anatolian region is not a plate (or 'platelet') sensu stricto but is undergoing distributed internal deformation. To evaluate the scale of neotectonic rotations in the transition zone near the western limit of tectonic escape and the border of the extensional domain in central-west Turkey, we have studied the palaeomagnetism at 82 sites in volcanic suites distributed along a similar to 140-km lineament with north-south trend and ranging in age from 18 to 8 Ma. Comparable deflection of magnetic remanence from the present field direction is identified along the full length of the lineament. A mean clockwise rotation of 12.3 +/- 4.2degrees is determined for this western sector of the Anatolian strike-slip province. Since similar rotations are observed in the youngest and oldest units, this cumulative rotation occurred after the late Miocene. When interpreted together with results elsewhere in Anatolia, it is inferred that the rotation is later than crustal thickening and uplift of the Anatolian Plateau and entirely a facet of the tectonic escape. Inclinations are mostly similar to 10degrees shallower than the predicted Miocene field and are considered to reflect the presence of a persistent inclination anomaly in the Mediterranean region. Larger rotations departing from the regional trend are also observed within the study region, but are confined to the vicinity of major faults, notably those bounding the Afyon-Aksehir Graben.