Boreal-tethyan correlation of the Jurassic-Cretaceous boundary interval by magneto - and biostratigraphy

As a result of detail sampling and paleomagnetic study of the 27- m- thick section of Jurassic - Cretaceous boundary beds in the Nordvik Peninsula ( Anabar Bay, Laptev Sea), a succession of M-zones correlative with chrons M20n - M17r is established for the first time in the Boreal deposits. Inside the normal polarity zone corresponding to Chron M20n, a thin interval of reversed polarity, presumably an equivalent of the Kysuca Sub-zone ( M20n. 1r), is discovered. The other thin interval of reversed polarity established within the next normal polarity zone ( M19n) is correlated with the Brodno Subzone ( M19n. 1r). The same succession of normal and reversed polarity zones has been discovered recently in the Jurassic - Cretaceous boundary beds of the Tethyan sections: in the Bosso Valley ( Italy), at the Brodno ( Slovak Republic) and Puerto Escano ( Spain) sites. Correlation of successions established lead us to conclusion, that the Jurassic - Cretaceous boundary corresponds in the Panboreal Superrealm to a level within the Craspedites taimyrensis Zone of the upper Volgian Substage. Hence, the greatest part of Volgian Stage should be included into the Jurassic System. Biostratigraphic data do not contradict this conclusion.