Carbon and oxygen isotope variations in Precambrian cherts
- California Institute of Technology, Pasadena (USA)
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 post-depositional 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 {delta}{sup 13}C value of ca. {minus}33{per thousand}/PDB is proposed for the Precambrian kerogen. The difference between Proterozoic and Phanerozoic ({minus}27{per thousand}) {delta}{sup 13}C values could be linked to the flowering of life at the end of the Precambrian.
- OSTI ID:
- 5557789
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Vol. 52:6; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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