First precise Jurasic/Cretaceous boundary correlation between Tethydian and Boreal regions based on magnetic polarities 145 Ma old rocks

Petr Pruner

The Boreal and the Tethyan Jurassic/Cretaceous boundary strata were successfully correlated for the first time using high resolution magnetostratigraphic investigations. According to present knowledge, the actually used provisional Boreal and the Tethyan J/K boundaries are heterochronous. All attempts to correlate the boundary J/K beds between the Boreal and the Tethyan realms by biostratigraphic methods failed. On several pilot localities (e.g. Bosso–Italy, Brodno–Slovakia, Puerto Escaňo–Spain; Nutzhof–Austria; Nordvik Peninsula–Russia) was successfully used for correlation the high resolution magnetostratigraphy together with detailed microbiozonation. We used these methods of high resolution magnetostratigraphy for the correlation the elaborated pilot sections and try to found suitable isochrones events for a proposal of definitive J/K boundary. International Commission on Stratigraphy (Subcommission on Cretaceous) submitted new proposal of fixing J/K boundary. The base of M18r (M18r / M19n interval) has been chosen in preference to short magnetic intervals and precise calibration of stratigraphic markers on wider geographical areas.

The research study was realized in close international cooperation with the Faculty of Science, Charles University; Nuclear Physics Institute ASCR; VŠB-Technical University of Ostrava; Geological Institute of RAS, Moscow; University of Granada and Napoli.