Palaeomagnetic study of the Karaman and Karapinar volcanic complexes, central Turkey: neotectonic rotation in the south-central sector of the Anatolian Block

In the Anatolian sector of the Afro-Eurasian collision zone a palaeotectoni c collisional phase (Paleocene to Miocene) responsible for emplacement of t he Pontide and Tauride orogens has been replaced by a neotectonic phase of continental deformation (Late Miocene/Early Pliocene to Recent). The latter phase appears to have been accommodated mainly by crustal thickening durin g Late Miocene and Pliocene times, but was succeeded by complex differentia l rotations of fault blocks during crustal extrusion in Late Pliocene and Q uaternary times. In this study we have investigated palaeomagnetism of Mioc ene-Recent volcanic rocks comprising the western extension of the Central A natolian Volcanic Province located in the south-central part of the Anatoli an Block with the aim of resolving deformations near to the border with the Tauride orogen. Rock magnetic investigations identify low-Ti magnetite ass emblages of primary cooling-related origin. These have predominant multidom ain structures but significant fractions of single domains are always prese nt; low-temperature alteration is largely absent. The Karaman Volcanic Comp lex (Late Pliocene) shows a net rotation of -5.7 +/- 6.9 degrees not signif icantly different from the regional field axis during Recent times. The Kar apinar Volcanic Field (Brunhes epoch) identifies a larger net rotation of - 23.1 +/- 12.0 degrees in a restricted sample. The adjoining Karacadag Volca nic Complex (Late Miocene-Pliocene) and Middle Miocene lavas beneath the Ha sandag Complex define net rotations of -8.1 +/- 5.9 degrees and -16.4 +/- 8 .9 degrees respectively. Analysis of palaeomagnetic results from Late Creta ceous-Recent rock units emplaced in Anatolia during the palaeotectonic and neotectonic regimes shows that rates of rotation have accelerated in post-P liocene times as crustal thickening has given way to tectonic escape. A nea r-uniform anticlockwise rotation of 25-35 degrees has characterised much of this block during the most recent phase of deformation and appears to have occurred in common with the Eurasian Plate to the north of the North Anato lian Fault Zone. Whilst this rotation appears to extend south eastwards acr oss the Ecemis Fault Zone towards the East Anatolian Fault, the present stu dy shows that smaller differential anticlockwise rotations have characteris ed the south-central region of the block where it has interacted at its sou thwestern margin with oroclinal bending focussed on the Isparta angle. (C) 1998 Elsevier Science B.V. All rights reserved.