Magneto- and carbon-isotope stratigraphy of the Lower-Middle Bathonian in the Sokur section (Saratov, Central Russia): implications for global correlation

Abstract

The discovery of Tethyan and Boreal fossils in Bathonian deposits of the Sokur section in the vicinity of Saratov (Central Russia) reopened the possibility of direct correlation of the Bathonian sections in different paleobiogeographic provinces, which require further integrated studies involving both paleontological (based on different groups of fauna) and physicochemical (paleomagnetic and isotope-geochemical) methods. Stable carbon isotope data for belemnite (Cylindroteuthididae) rostra from the Sokur section show that the Subboreal Oraniceras besnosovi Zone and Boreal Arcticoceras harlandi Subzone are correlated with the Zigzag Zone of the standard scale, whereas the Boreal A. ishmae Subzone can be correlated completely or, even partly, with the Tenuiplicatus Zone. We identified equivalents of chrons of the geomagnetic polarity time scale (GPTS): e-Bath N, m-Bath R, and lt-Bath N, corresponding to the Lower-Middle Bathonian and, possibly, lowermost Upper Bathonian.