The low 13C/12C ratio in some Neoproterozoic carbonates is considered to be evidence of carbon cycle perturbations unique to the Precambrian. Here, all published oxygen and carbon isotope data for Neoproterozoic marine carbonates are compiled. The combined isotope systematics are found to be identical to those of well-understood Phanerozoic examples, suggesting an influx of photosynthetic carbon rather than perturbations to the carbon cycle — and implying an explosion of photosynthesizing communities on late Precambrian land surfaces.
- L. Paul Knauth
- Martin J. Kennedy
