ИСТИНА

Kashpir reference section is located to the south of Syzran’ town near Kashpir Village, on the right bank of Volga River (N 53º01′56″, E 48º27′05″), where Middle Volgian – Hauterivian deposits are exposed (Fig. 1). Kashpir is one of historical sections of the Volgian Stage, which was reported in numerous publications and was proposed as the stratotype of Kashpurian Stage by I.G. Sasonova and N.T. Sasonov. The Jurassic – Cretaceous transition interval of the section has been re-described recently (Rogov et al., 2015) and characterised by ammonites (Rogov et al., 2015; Baraboshkin et al., 2015), belemnites and Buchias (Dzyuba, Urman, Shurygin, 2015), palynomorphs (Harding et al., 2011; Pestchevitskaya, Lebedeva, Ryabokon, 2011), ostracods (Kolpenskaya, 1995), stable isotopes (Gröcke et al., 2003, the Ryazanian only), palaeomagnetic and mineralogical data (Baraboshkin et al., 2015; Ruffell et al., 2002). Therefore, Kashpir section is one of the most well-studied sections in Subboreal Realm. Even if it is highly condensed, it contains a number of potential direct markers (ammonites, belemnites, buchiids and dinocysts; palaeomagnetic reversal and stable isotope data), which could be used for interregional correlation of J/K boundary interval (Figs. 1, 2). Unfortunately only stable isotopes and palaeomagnetic reversals one may use for the direct Boreal–Tethyan correlation of the both Tithonian / Volgian and Berriasian / Ryazanian. It needs additional study. Nevertheless, Kashpir section could be proposed as auxiliary section in Subboreal Realm to the GSSP, which hopefully will be chosen in the future.