New minimal 87SR/86SR values in biogenic carbonates of the Permian of the Omolon massif (North-Eastern Asia)

For the first time very low values (up to 0,706707) of the ratio 87Sr/86Sr were recorded in the biogenic carbonates of the Omolon massif (Northeast Asia) of the Capitanian age. These results are in good agreement with previously obtained data on limestones in Japan (Kani et al., 2013; 2018). In general, the strontium ratio curve constructed by us repeats the well-known world trend, differing by its somewhat underestimated (by an average of 0,000-0,0008) its values. The Capitanian strontium minimum can be associated with the entry into the ocean of significant amounts of lightweight femic strontium due to a sharp increase in paleospreading. The maximum values of the strontium ratio, obtained from the middle part of the Intomodesma evenicum bivalve Subzone are 0,706986, which corresponds to the upper part of the Wuchiapingian stage.