Carbon-isotope evidence reported from 3.7 Ga Isua sediments

Assembled from 14 blocks · 1 evidence · 6 related

1. Story
2. Minik Rosing reported graphite microparticles in more than 3,700 million-year-old seafloor turbidites from Isua in West Greenland whose carbon-13 content is depleted to a degree characteristic of biological carbon fixation. Organisms preferentially take up the lighter isotope, so biological carbon is isotopically light and the residual inorganic pool is correspondingly heavy — a fractionation that is easy to measure and hard to produce abiotically at the same magnitude. The claim is important because it does not depend on any structure being biological in shape, which is the weak point of every stromatolite and microfossil claim of comparable age. Its own weak point is that certain abiotic reactions, including some hydrothermal and metamorphic processes, can produce isotopically light carbon, so the argument turns on how large a fractionation is achievable without life.
3. Knowledge
4. Isua supracrustal belt, southwest Greenland
5. Carbon-isotope evidence reported from 3.7 Ga Isua sediments
6. Connections
7. Isua supracrustal belt, southwest Greenland
8. The origin of life
9. The origin of life
10. Carbon-isotope evidence reported from 3.7 Ga Isua sediments
11. Structures at Isua are reported as 3.7 Ga stromatolites
12. The Isua stromatolite claim is reassessed and rejected
13. Evidence
14. Supports the carbon-isotope evidence for biological carbon fixation in more than 3.7 Ga Isua sediments. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked. Volume and page range are quoted from standing knowledge and were not re-checked.