ASSESSMENT OF DIACHRONISM OF BIOSTRATIGRAPHIC BOUNDARIES BY MAGNETOCHRONOLOGICAL CALIBRATION OF ZONAL SCALES FOR THE LOWER CRETACEOUS OF THE TETHYAN AND BOREAL BELTS

Abstract

Complex bio- and magnetostratigraphic studies of Lower Cretaceous deposits in the central Volga region, Northern Caucasus, and other regions carried out by the authors of the present communication for more than 10 years resulted in the detailed correlation of biostratigraphic zonal scales between each other (mainly upper Hauterivian–Aptian) and with the “standard” scale of the Western Mediterranean. Paleomagnetic inversions are known to be synchronous for all rock sequences on the earth regardless of the latitude of their formation. Therefore, correlation of regional magnetoand biostratigraphic scales (magnetochronological calibration) allowed us to establish and assess quantitatively for the first time the asynchronous nature of the series of stratigraphic boundaries, which were regarded as synchronous for different paleogeographic belts.