| Titre | Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation |
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| Auteur | Bond, D; Grasby, S E |
| Source | Geology vol. 48, 2020 p. 1-5, https://doi.org/10.1130/G47377.1  Accès ouvert |
| Image |  |
| Année | 2020 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20200056 |
| Éditeur | Geoscience World |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/G47377.1 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Sujets | extinctions biotiques; volcanisme; isotopes de carbone; pluies acides; météorites; géochimie atmosphérique; paléoclimats; écologie marine; milieux marins; paléontologie; Phanérozoïque; Cambrien;
Ordovicien; Silurien; Dévonien; Permien; Jurassique |
| Illustrations | tableaux; diagrammes stratigraphiques; diagrammes schématiques; cartes de localisation |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Gestion de programme de l'ouest de l'Arctique |
| Diffusé | 2020 05 18 |
| Résumé | (disponible en anglais seulement)
The Ordovician saw major diversification in marine life abruptly terminated by the Late Ordovician mass extinction (LOME). Around 85% of species were eliminated
in two pulses 1 m.y. apart. The first pulse, in the basal Hirnantian, has been linked to cooling and Gondwanan glaciation. The second pulse, later in the Hirnantian, is attributed to warming and anoxia. Previously reported mercury (Hg) spikes in
Nevada (USA), South China, and Poland implicate an unknown large igneous province (LIP) in the crisis, but the timing of Hg loading has led to different interpretations of the LIP-extinction scenario in which volcanism causes cooling, warming, or
both. We report close correspondence between Hg, Mo, and U anomalies, declines in enrichment factors of productivity proxies, and the two LOME pulses at the Ordovician-Silurian boundary stratotype (Dob's Linn, Scotland). These support an extinction
scenario in which volcanogenic greenhouse gases caused warming around the Katian-Hirnantian boundary that led to expansion of a preexisting deepwater oxygen minimum zone, productivity collapse, and the first LOME pulse. Renewed volcanism in the
Hirnantian stimulated further warming and anoxia and the second LOME pulse. Rather than being the odd-one-out of the "Big Five" extinctions with origins in cooling, the LOME is similar to the others in being caused by volcanism, warming, and
anoxia. |
| GEOSCAN ID | 326103 |
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