Neogene anticlockwise rotation of central Anatolia (Turkey): preliminary palaeomagnetic and geochronological results

Abstract

A palaeomagnetic and geochronological study was carried out on fifty sites from the Neogene volcanic province of central Anatolia. Results from this analysis show that there has been a progressive anticlockwise rotation of this region over the period spanning at least the last 10–12 Ma. We interpret this rotation as having resulted from the collision of Arabia with Anatolia along the Bitlis suture. If we assume a constant rate of rotation we obtain a rate of 2.4°/Ma. This value is significantly higher than the present-day rotation rate obtained from GPS (1.3±0.1°/Ma) and also implies that these rocks have been rotating at their present rate since well before collision occurred along the Bitlis suture (∼12 Ma): a geologically unreasonable conclusion. If, however, we combine these data with data from other palaeomagnetic studies with good age control the resultant curve seems to show three distinct linear segments: (1) 0–5 Ma with a very slow rate of rotation (1.2°/Ma); (2) 5–12 Ma where we observe a rapid increase of rotation rate to 6.5°/Ma; and (3) >12 Ma, when the rotation rate is again essentially zero (−0.041°/Ma). These results are generally consistent with a model calling for Middle Miocene collision along the Bitlis suture and Late Plio–Pleistocene initiation of motion along the North and East Anatolian fault zones.