New results and a palaeomagnetic overview of the Pontides in northern Turkey

Abstract

SUMMARY Palaeomagnetic results are reported from 16 sites within volcanic and volcano-sedimentary rocks of Cretaceous and Eocene age from the central Pontides in northern Turkey. The sampled area is bounded by the North Anatolian Fault (NAF) to the south and the Black Sea to the north. The palaeomagnetic data collected demonstrate the presence of both non-rotated and anticlockwise rotated regions; (i) declination directions including Lower–Upper Cretaceous and Eocene sites do not indicate any significant rotations north of where the NAF exhibits an arcuate shape, (ii) 20° anticlockwise rotation was observed in the Sinop peninsula, the northernmost extremity of the central Pontides, (iii) in the west of the central Pontides, two sites with normal and reversed antipodal directions indicate a 20° anticlockwise rotation and (iv) another region lies to the east of the study area and shows a rotation in an anticlockwise sense of about 5°–30°. The Upper Cretaceous and Eocene directions reported in this paper and other palaeomagnetic studies show that there is not much difference between the inclination values of the Upper Cretaceous (I= 40.1°, α95= 7.2°) and the Eocene sites (I= 39.6°, α95= 8.1°). Furthermore, the values of the inclination available from both sedimentary and volcanic Upper Jurassic–Lower Cretaceous formations are shallower than the Upper Cretaceous ones. This suggests that the entire Pontides have undergone a northward drift of over 2000 km since the Upper Jurassic.