Mulde event explained

The Mulde event was an anoxic event, and marked the second of three relatively minor mass extinctions (the Ireviken, Mulde, and Lau events) during the Silurian period. It coincided with a global drop in sea level, and is closely followed by an excursion in geochemical isotopes. Its onset is synchronous with the deposition of the Fröjel Formation in Gotland.^[1] Perceived extinction in the conodont fauna, however, likely represent a change in the depositional environment of sedimentary sequences rather than a genuine biological extinction.^[2]

Higher resolution δ¹³C isotope analysis identifies differences in the organic and carbonate carbon isotope curves (Δ¹³C), allowing the inference of a sustained drop in CO₂ levels coincident with the extinction once sedimentological data are taken into account.^[3]

Notes

The Ireviken, Mulde, and Lau events were all closely followed by isotopic excursions.

Notes and References

1. Samtleben, C. . Munnecke, A. . Bickert, T. . 2000 . Development of facies and C/O-isotopes in transects through the Ludlow of Gotland: Evidence for global and local influences on a shallow-marine environment . Facies . 43 . 1 . 1–38 . 10.1007/BF02536983. 2000Faci...43....1S . 130640332 .
2. 10.1111/pala.12326. Harnessing stratigraphic bias at the section scale: Conodont diversity in the Homerian (Silurian) of the Midland Platform, England. Palaeontology. 2017. Jarochowska. Emilia. Ray. David C. Röstel. Philipp. Worton. Graham. Munnecke. Axel. 61. 57–76. 135200300 . free.
3. 10.1016/j.chemgeo.2021.120256 . 0009-2541 . Asynchronous δ13Ccarb and δ13Corg records during the onset of the Mulde (Silurian) positive carbon isotope excursion from the Altajme core, Gotland, Sweden . 2021 . Biebesheimer . Ellie J. . Cramer . Bradley D. . Calner . Mikael . Barnett . Bruce A. . Oborny . Stephan C. . Bancroft . Alyssa M. . Chemical Geology . 576 . 120256 . 2021ChGeo.57620256B . 234817512 .