Stable isotope measurements along the rivers Malaya Kuonamka and Bol'shaya Kuonamka in Siberia

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 100km apart in the Tommotian-Atdabanian portion ofthe 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.