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Carbon and oxygen isotope variations in precambrian cherts

Robert, François (1988) Carbon and oxygen isotope variations in precambrian cherts. Geochimica et Cosmochimica Acta, 52 (6). pp. 1473-1478. ISSN 0016-7037. doi:10.1016/0016-7037(88)90218-9.

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Isotopic compositions of O in bulk Precambrian cherts and of C in the insoluble organic matter trapped in the silica have been determined. A general negative correlation relates these two variables and indicates that postdepositional alteration may have markedly modified the pristine isotopic ratios of the C compounds and their hosts. This interpretation is in good agreement with the expected isotopic trends for C and O resulting from secondary geological thermal events. Based on this correlation, a maximum δ^(13)C value of ca.− 33%.PDB is proposed for the Precambrian kerogen. The difference between Proterozoic and Phanerozoic (−27%.) δ^(13)C values could be linked to the flowering of life at the end of the Precambrian.

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Additional Information:© 1988 Published by Elsevier Ltd. Received 15 July 1986, Accepted 17 February 1988. I am grateful to S. Epstein for his financial, scientific and above all personal support, which made the present study possible. I thank L. P. Knauth and J. W. Schopf for generously contributing samples and geological information about the problems studied in this paper. Scientific discussions with J. A. Karhu on oxygen isotopes in cherts were of great help. I thank J. O’Neil, M. Schidlowski, J. M. Hayes and J. Veizer for their careful reviews, J. Halbout for his help in English and C. Godecaux for her help in drafting the figures. This work was supported by NSF grant (EAR-8313086).
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Issue or Number:6
Record Number:CaltechAUTHORS:20171122-083350850
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Official Citation:François Robert, Carbon and oxygen isotope variations in precambrian cherts, In Geochimica et Cosmochimica Acta, Volume 52, Issue 6, 1988, Pages 1473-1478, ISSN 0016-7037, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:83424
Deposited By: Tony Diaz
Deposited On:22 Nov 2017 17:18
Last Modified:15 Nov 2021 19:58

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