C and Sr Isotope Chemostratigraphy and Pb–Pb Age of Carbonate Deposits of the Vorogovka Group (Neoproterozoic), Northwest of the Yenisei Range

Abstract

The C and Sr isotopic signatures and the Pb–Pb age of carbonate sedimentary rocks of the Vorogovka Group in the reference section in the Vorogovka River valley, northwestern Yenisei Range, were obtained. The deposits of the group ascribed to the Severnaya Rechka, Mutnina, and Sukhaya Rechka Formations fill a large trough, and lithological and textural features indicate a high sedimentation rate. Most of the carbonate rocks are represented by limestones with low Fe/Sr and Mn/Sr ratios and average δ18O value (–6.0 ± 1.6‰ V-PDB), indicating the well-preserved isotope systems of the rocks. The 87Sr/86Sr ratios and δ13С values vary within narrow limits of 0.70816–0.70826 and –1.4 to +0.8‰ for Upper Severnaya Rechka limestones and 0.70818–0.70829 and +1.0 to +2.0‰ for Sukhaya Rechka limestones, respectively. The Pb–Pb isochrone ages of carbonate rocks of the Severnaya Rechka and Sukhaya Rechka formations are 580 ± 40 Ma (MSWD = 1.4) and 565 ± 90 Ma (MSWD = 1.1), respectively. According to chemostratigraphic and isotope-geochronological data, the accumulation of limestones of the Vorogovka Group could have occurred at 580–550 Ma, that corresponds to the Late Vendian or Late Ediacaran. It is evident that the duration of accumulation of Vorogovka Group did not exceed 10–15 m.y. The Vorogovka Trough is different from in the sedimentation pattern from other Late Vendian marginal troughs at the southwestern part of the Siberian Platform and formed independently.