New palaeomagnetic results from the Polish part of the Pieniny Klippen Belt, Carpathians--evidence for the palaeogeographic position of the Czorsztyn Ridge in the Mesozoic

摘要

Middle and Upper Jurassic limestones from the Polish part of the Pieniny Klippen Belt (PKB) were palaeomagnetically studied at six localities. The Middle Jurassic red crinoidal limestones of the Krupianka Limestone Formation and Oxfordian radiolarites of the Czajakowa Radiolarite Formation, sampled in the eastern part of the Polish section of the PKB, were either unsuitable for palaeomagnetic studies (Krupianka Klippe) or remagnetized in the Neogene (Baba and Zaskalskie-Bodnarowka klippen). The Czorsztyn Limestone Formation was investigated at the localities of Krempachy (upper Middle Jurassic: uppermost Bajocian?-Callovian?), Oblazowa (middle Oxfordian) and Rogoznik (Rogoza Coquina Member - Kimmeridgian). A pre-folding, mixed polarity component of magnetization was revealed, which was interpreted as primary. Palaeoinclinations differ slightly, but not significantly, between localities. The palaeolatitude of the Polish sector of the PKB, averaged for the Middle/Upper Jurassic, amounts to 22 deg N (+ - 5 deg). It corresponds to the estimated palaeolatitudes of the northern margins of the Adriatic microplate and indicates a significantly large distance from the European plate. There is a growing evidence for a northward drift of the PKB in the Late Jurassic up to the earliest Cretaceous: from the palaeolatitude of 22 deg N in the Late Jurassic up to 28 deg N in the western part, in Poland/W Slovakia, and from 28 deg up to 36 deg N in the eastern part of the PKB in Ukraine. Systematically lower palaeolatitudes in the west combined with existing palaeogeographic and geotectonic scenarios would account for a NE-SW orientation of the Czorsztyn Ridge in the Late Jurassic/earliest Cretaceous.