A Vendian-Cambrian boundary succession from the northwestern margin of the Siberian Platform: stratigraphy, palaeontology, chemostratigraphy and correlation.
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 upper-most 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.
Bartley
J K
JK
Botanical Museum, Harvard University, Cambridge, MA 02138, USA. jbartley@westga.edu
Pope
M
M
Knoll
A H
AH
Semikhatov
M A
MA
Petrov PYu
D005075:Biological Evolution; D002247:Carbon Isotopes; D002254:Carbonates / Q000032:analysis*; D005580:Fossils; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D055593:Geological Phenomena; D005844:Geology; D019110:Meteoroids; D010103:Oxygen Isotopes; D010163:Paleontology; D012800:Siberia
D002247:Carbon Isotopes; D002254:Carbonates; D010103:Oxygen Isotopes