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Carbon isotope stratigraphy of the Precambrian–Cambrian Sukharikha River section, northwestern Siberian platform

Published online by Cambridge University Press:  16 April 2007

ARTEM KOUCHINSKY
Affiliation:
Department of Palaeozoology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden
STEFAN BENGTSON
Affiliation:
Department of Palaeozoology, Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden
VLADIMIR PAVLOV
Affiliation:
Institute of Physics of the Earth, Bol'shaya Gruzinskaya 10, Moscow 123995, Russia
BRUCE RUNNEGAR
Affiliation:
NASA Astrobiology Institute, MS 240–1, Ames Research Center, Moffett Field, California 94035, USA
PETER TORSSANDER
Affiliation:
Department of Geology and Geochemistry, Stockholm University, SE-106 91 Stockholm, Sweden
EDWARD YOUNG
Affiliation:
Department of Earth and Space Sciences, University of California, Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, California 90095-1567, USA
KAREN ZIEGLER
Affiliation:
Department of Earth and Space Sciences, University of California, Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, California 90095-1567, USA

Abstract

A high-resolution carbon isotope profile through the uppermost Neoproterozoic–Lower Cambrian part of the Sukharikha section at the northwestern margin of the Siberian platform shows prominent secular oscillations of δ13C with peak-to-peak range of 6–10 ‰. There are six minima, 1n–6n, and seven maxima 1p–7p, in the Sukharikha Formation and a rising trend of δ13C from the minimum 1n of − 8.6 ‰ to maximum 6p of + 6.4 ‰. The trough 1n probably coincides with the isotopic minimum at the Precambrian–Cambrian boundary worldwide. Highly positive δ13C values of peaks 5p and 6p are typical of the upper portion of the Precambrian–Cambrian transitional beds just beneath the Tommotian Stage in Siberia. A second rising trend of δ13C is observed through the Krasnoporog and lower Shumny formations. It consists of four excursions with four major maxima that can be correlated with Tommotian–Botomian peaks II, IV, V, and VII of the reference profile from the southeastern Siberian platform. According to the chemostratigraphic correlation, the first appearances of the index forms of archaeocyaths are earlier in the Sukharikha section than in the Lena–Aldan region.

Type
Original Article
Copyright
© 2007 Cambridge University Press

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