Abstract
The characteristic difference of some 20 to 30 ‰ in the 13C/ 12C rations of reduced (organic) and oxidized (carbonate) carbon as observed in the contemporary environment can be traced back over 3.5 (if not 3.8) Ga of recorded Earth history. There is little doubt that the enrichment of isotopically light carbon in fossil organic matter ultimately derives from the bias in favor of 12C during photosynthetic carbon fixation (notably the RuBP carboxylase reaction of the Calvin cycle). Accordingly, the mainstream of the sedimentary δ 13C org record can be most reasonably explained as geochemical evidence of the isotope-discriminating properties of the principal CO 2-fixing enzymatic reaction of the assimilatory pathway, thus giving eloquent testimony to an extreme degree of evolutionary conservatism in the biochemistry of autotrophic carbon fixation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
