Javascript är avstängt eller blockerat i din webbläsare. Detta kan leda till att vissa delar av vår webbplats inte fungerar som de ska. Sätt på javascript för optimal funktionalitet och utseende.

Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Mikael Calner

Mikael Calner

Professor

Mikael Calner

Osmium and lithium isotope evidence for weathering feedbacks linked to orbitally paced organic carbon burial and Silurian glaciations

Författare

  • Adam D. Sproson
  • Philip A.E. Pogge von Strandmann
  • David Selby
  • Emilia Jarochowska
  • Jiří Frýda
  • Jindřich Hladil
  • David K. Loydell
  • Ladislav Slavík
  • Mikael Calner
  • Georg Maier
  • Axel Munnecke
  • Timothy M. Lenton

Summary, in English

The Ordovician (∼487 to 443 Ma) ended with the formation of extensive Southern Hemisphere ice sheets, known as the Hirnantian glaciation, and the second largest mass extinction in Earth History. It was followed by the Silurian (∼443 to 419 Ma), one of the most climatically unstable periods of the Phanerozoic as evidenced by several large scale (>5‰) carbon isotope (δ13C) perturbations associated with further extinction events. Despite several decades of research, the cause of these environmental instabilities remains enigmatic. Here, we provide osmium (187Os/188Os) and lithium (δ7Li) isotope measurements of marine sedimentary rocks that cover four Silurian δ13C excursions. Osmium and Li isotope records resemble those previously recorded for the Hirnantian glaciation suggesting a similar causal mechanism. When combined with a new dynamic carbon-osmium-lithium biogeochemical model we suggest that astronomical forcing of the marine organic carbon cycle, as opposed to a decline in volcanic arc degassing or the rise of early land plants, resulted in drawdown of atmospheric CO2, triggering continental scale glaciation, intense global cooling and eustatic sea-level lows recognised in the geological record. Lower atmospheric pCO2 and temperatures during the Hirnantian and Silurian glaciations suppressed CO2 removal by silicate weathering, driving 187Os/188Os and δ7Li variability, supporting the existence of climate-regulating feedbacks.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2022-01-01

Språk

Engelska

Publikation/Tidskrift/Serie

Earth and Planetary Science Letters

Volym

577

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geology

Nyckelord

  • eccentricity and precession
  • Hirnantian glaciation
  • orbital obliquity
  • osmium (Os/Os) and lithium (δLi) isotopes
  • silicate weathering
  • Silurian palaeoclimate

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0012-821X