The Shuram excursion
Carbon isotopes plunge further than at any other time in Earth's history, and nobody is sure why.
- When
- —
- Duration
- 7 million years
- Known to
- ± 5 million years
- Era
- Neoproterozoic, Proterozoic
Marine carbonates worldwide record δ¹³C values as low as −12‰ over a span of up to 10 million years — the deepest and longest negative excursion known. Interpretations range from the oxidation of an enormous reservoir of dissolved organic carbon to a fundamental reorganisation of ocean circulation, with some arguing the signal is diagenetic rather than original. It sits immediately before the diversification of the Ediacaran biota.