As a result of the complex analysis of petromagnetic, micro- and macrofaunistic data of deposits on the Kallovian – Oxfordian boundary of Dubki section (Saratov), which is one of candidates for a role of a Global Boundary Stratotype Section and Point of Oxfordian boundary (GSSP), it is established significant correlation between magnetic susceptibility variations and changes of an abundance, a specific variety of ostracodes, foraminiferes and ammonites.