Tectonic rotations south of the Bohemian Massif from palaeomagnetic directions of Permian red beds in Hungary

Abstract

Palaeomagnetic studies were carried out in Permian red beds of the Balaton Highlands, the Mecsek Mountains and the Bükk Mountains of Hungary. Statistically well defined directions were obtained from six localities in the Balaton Highlands and two localities in the Mecsek Mountains. No meaningful results were obtained from the Bükk Mountains. Three magnetic components were identified from red beds of the Balaton Highlands: (1) in haematite with a very high unblocking temperature (700°C), interpreted as a Permian magnetization (D c = 79°, I c = -11°, k = 24, α 95 = 13.6°), in six samples from three beds in a single locality (2) a secondary but ancient component residing mainly inmaghemite (D = 314°, I = 49°, k = 48, α 95 = 10.0°), in 84 samples from six localities with a within-locality scatter increasing on unfolding; and (3) a direction parallel to the present field (D = 7°, I = 62°, k = 46, α 95 =7.7°), in nine samples from a single locality. For the Balaton Highlands, the component 1 direction agrees with directions obtained from Permian red beds and volcanics in the eastern part of the Southern and Eastern Alps and the Inner West Carpathians. All show large, apparent rotations relative to stable Europe since the Permian. Component 2 is of post-folding (post-Aptian) age. Its direction agrees with known Late Cretaceous directions from the Transdanubian Central Mountains, which also show significant counterclockwise rotation relative to stable Europe. The characteristic magnetization for the Mecsek Mountains resides in haematite and may be primary. The directions indicate only a slight net counterclockwise rotation of the Mecsek Mountains with respect to stable Europe since the Permian.