Southward migration of arc magmatism during latest Cretaceous associated with slab steepening, East Pontides, N Turkey: New paleomagnetic data from the Amasya region

Abstract

A new paleomagnetic study was carried out on the Findikli formation in the Amasya region, which is to the north of the Ankara-Erzincan Neotethyan suture zone, in order to better understand the paleogeographic evolution of the Pontides tectonic belt during the Maastrichtian. Samples were collected from volcanoclastic sandstones and lavas at 51 sites. Rock magnetic experiments identified pseudo-single domain (PSD) titanomagnetite as the main magnetic carriers at the majority of sites. Progressive thermal and alternating demagnetization revealed that the characteristic remanent component is removed between 400 and 580 degrees C or 20-100 ml, respectively. A high temperature component, which indicates the presence of titano-hematite, is found only in some lavas. Declinations show a systematic dispersion across the study area related to tectonic rotations about vertical axes. Inclinations are consistent, however, and yield a mean paleolatitude of 20.0 degrees N +/- 2.5 degrees for the Maastrichtian. Comparison of the results from this study with the reference direction of the East Pontides from the Turonian-Campanian is best explained with a model involving slab roll-back and marginal basin formation between 90 and 65 Ma period. (C) 2010 Elsevier B.V. All rights reserved.