Carbon isotopic oscillations are useful to elucidate the stratigraphy and biogeochemical
events around the Precambrian–Cambrian transition. New isotopic data from the Manykaj and
Emyaksin formations of the eastern Anabar Uplift (Siberia) help to correlate the Lower Cambrian
and Neoproterozoic–Cambrian transitional beds across the Siberian Platform. The similarity of
trends and amplitudes of the carbon isotopic curves, together with biostratigraphic and sequence-stratigraphic
markers from the Anabar Uplift, provide a precise correlation with the southern part of
the Siberian Platform. Diagenesis of argillaceous limestones of the Emyaksin Formation has apparently
not affected the primary isotopic variations. The resulting curve is nearly identical in sections
about 100 km apart in the Tommotian–Atdabanian portion of the formation. Relatively frequent and
pronounced isotopic oscillations in the lower beds of the Emyaksin Formation fit between features I
and II of the southern Siberian isotopic reference scale but are undetected therein owing to the depositional
hiatus at the base of the Tommotian Stage in its type section. This confirms the transgressive
onlap from the north suggested by previous studies, and makes the appearance of the Cambrian skeletal
fossils on the Siberian Platform less abrupt. The hiatus in the south appears to embrace at least two
biostratigraphic zones as recognized in the north. The case is strengthened for a pre-Tommotian
Cambrian Stage in Siberia, the biostratigraphic framework for which has been elaborated earlier.