Paleomagnetism and the Alpine tectonics of Eurasia IV : Jurassic, Cretaceous and Eocene pole positions from northeastern Turkey

Abstract

In April 1965 and May 1966 several groups of samples were collected by the author in northern and eastern Turkey in view of a study of their magnetic properties.

The characteristic magnetizations of four groups of Eocene and Cretaceous volcanic rocks and sediments had the following directions of magnetization and virtual pole positions (after demagnetization and correction for the tectonical dip): Eocene:(Tunceli) D = 152.5°, I = − 48° and pole 65°N, 66°W.* Upper Cretaceous-Eocene:(Gümüshane) D = 346°, I = +40° and pole 69.5°N, 98.5°W. Cretaceous:(Gümüshane) D = 153.5°, I = − 36.5° and pole 60.5°N, 81.5°W. Cretaceous:(Niskar) D = 140°, I = − 36° and pole 51°N, 64°W.

For one group of Jurassic sandstones from the Bayburt-Gümüshane region it proved to be very difficult to determine accurately the characteristic direction of magnetization: the samples contained secondary magnetizations, concealing the ancient natural remanent magnetization (N.R.M.). The result is therefore regarded as unreliable. Three groups, varying in age from Permian to Eocene, contained only present-day local geomagnetic field directions and these directions are considered to be secondary.

As the most simple interpretation of previous data and the above mentioned results, the author suggests the hypothesis that Turkey, the Arabian Shield and Africa have acted as one drifting unit since Late Mesozoic times.