Geological Magazine



A Vendian–Cambrian boundary succession from the northwestern margin of the Siberian Platform: stratigraphy, palaeontology, chemostratigraphy and correlation


JULIE K. BARTLEY a1c1p1, MICHAEL POPE a2, ANDREW H. KNOLL a1, MIKHAIL A. SEMIKHATOV a3 and PETER YU. PETROV a3
a1 Botanical Museum, Harvard University, 26 Oxford St., Cambridge, MA 02138, USA
a2 Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
a3 Geological Institute, Russian Academy of Sciences, Moscow 109017, Russian Federation

Abstract

Siberia contains several key reference sections for studies of biological and environmental evolution across the Proterozoic–Phanerozoic transition. The Platonovskaya Formation, exposed in the Turukhansk region of western Siberia, is an uppermost Proterozoic to Cambrian succession whose trace and body fossils place broad limits on the age of deposition, but do not permit detailed correlation with boundary successions elsewhere. In contrast, a striking negative carbon isotopic excursion in the lower part of the Platonovskaya Formation permits precise chemostratigraphic correlation with uppermost Yudomian successions in Siberia, and possibly worldwide. In addition to providing a tool for correlation, the isotopic excursion preserved in the Platonovskaya and contemporaneous successions documents a major biogeochemical event, likely involving the world ocean. The excursion coincides with the palaeontological breakpoint between Ediacaran- and Cambrian-style assemblages, suggesting a role for biogeochemical change in evolutionary events near the Proterozoic–Cambrian boundary.

(Received January 15 1997)
(Accepted January 15 1998)


Correspondence:
c1 Author for correspondence.
p1 Present address – Geology Department, State University of West Georgia, Carrollton, GA 30118, USA; jbartley@westga.edu


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