Integrated chronostratigraphy of the Vendian System of Siberia: implications for a global stratigraphy

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Abstract
Integrated δ 13 C chemostratigraphy and sequence stratigraphy are developed for a succession of Vendian strata (Nokhtuisk section) on the southern margin of the Siberian platform. The carbonates exhibit secular variations in δ 13 C and at least three major depositional sequences that encompass the last c. 20 million years –(<565–545 Ma) of Vendian time. Correlation of these events with key sections in eastern Siberia reveals the development of three cratonic sequences that partition the Vendian System of Siberia into high-resolution time slices (third-order sequences). The third-order events form a larger depositional sequence, which is correlated with greater confidence on a global-scale. With the aid of global chemostratigraphic constraints, the second-order sequence in Siberia is interpreted to represent the youngest of at least two sequences of eustatic origin that span the latest 60 million years of terminal Neoproterozoic time. Evidence for repeated glaciations in many basins at this time provides a plausible mechanism for the third-order cratonic sequences in Siberia. However, effects due to sea-floor spreading related to the break-up of the supercontinent Rodinia are invoked as the primary mechanism for the longer-term, second-order sea-level fluctuations.