It coincided with a global drop in sea level, and is closely followed by an excursion[clarification needed] in geochemical isotopes.
Its onset is synchronous with the deposition of the Fröjel Formation in Gotland.
[4] Perceived extinction in the conodont fauna, however, likely represent a change in the depositional environment of sedimentary sequences rather than a genuine biological extinction.
[5] 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.
[6] ^1 The Ireviken, Mulde, and Lau events were all closely followed by isotopic excursions.