The Great Oxidation Event

Assembled from 48 blocks · 2 evidence · 31 related

1. Story
2. The irreversible appearance of free oxygen in Earth's atmosphere, and the largest change any organism has ever made to the planet. Oxygenic photosynthesis in cyanobacteria had probably been operating for some time before this, but the oxygen produced was consumed by reduced iron and sulfur in the oceans and by volcanic gases; the event is the point at which production finally exceeded that sink. The evidence is not the presence of oxygen but the disappearance of a signature that requires its absence: the mass-independent fractionation of sulfur isotopes vanishes from the sedimentary record, and it cannot be regenerated once an ozone layer exists. Concentrations after the transition are poorly constrained — probably somewhere between a fraction of a per cent and a few per cent of present atmospheric levels, far below modern values — and the rise was not monotonic, with evidence of transient oxygen pulses before it and a substantial excursion after. The consequences include the loss of most of the anaerobic biosphere to what was, for it, a poison.
3. Knowledge
4. Stromatolites
5. Mass-independent fractionation of sulfur isotopes
6. Banded iron formations
7. Endosymbiosis and the eukaryotic cell
8. The Great Oxidation Event
9. The Cambrian explosion
10. Connections
11. LUCA — the last universal common ancestor
12. Mass-independent fractionation of sulfur isotopes
13. Banded iron formations
14. The origin of life
15. Stromatolites
16. The Cambrian explosion
17. Endosymbiosis and the eukaryotic cell
18. Mass-independent fractionation of sulfur isotopes
19. Banded iron formations
20. The origin of life
21. The Great Oxidation Event
22. Structures at Isua are reported as 3.7 Ga stromatolites
23. The Isua stromatolite claim is reassessed and rejected
24. Molecular clock dating
25. Ediacara Hills, Flinders Ranges
26. Fortune Head GSSP, Newfoundland
27. Konservat-Lagerstätte (exceptional preservation)
28. Burgess Shale, Yoho National Park
29. Anomalocaris
30. Chengjiang fossil site, Yunnan
31. The Great Oxidation Event
32. The end-Ordovician mass extinction
33. Fortune Head GSSP, Newfoundland
34. Burgess Shale, Yoho National Park
35. Chengjiang fossil site, Yunnan
36. Anomalocaris
37. Konservat-Lagerstätte (exceptional preservation)
38. Molecular clock dating
39. The evolution of multicellularity
40. The Great Oxidation Event
41. The Great Oxidation Event
42. The Great Oxidation Event
43. Sulfur mass-independent fractionation is proposed as an atmospheric oxygen proxy
44. The Great Oxidation Event
45. The Great Oxidation Event
46. Evidence
47. Supports the use of mass-independent sulfur isotope fractionation as a proxy for an anoxic, ozone-free atmosphere and its disappearance as a marker of the Great Oxidation Event. 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.
48. Supports the general Precambrian narrative used here: stromatolite biogenicity reasoning, banded iron formation requirements, endosymbiotic origin of organelles and the framing of mass extinction as a measurement problem. Published in 2003, so it predates the 2016, 2018 and 2024 results also cited in this pack. 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.