The Mulde event was an anoxic event, and marked the second of three relatively minor
mass extinction
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
Lau
Lau or LAU may refer to:
People
* Lau (surname)
* Liu (劉/刘), a common Chinese family name transliterated Lau in Cantonese and Hokkien
* Lau clan, one of the Saraswat Brahmin clans of Punjab
* LAU (musician): Laura Fares
Places
* Lebane ...
events) during the
Silurian
The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleoz ...
period. It coincided with a global drop in sea level, and is closely followed by an excursion in
geochemical
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass num ...
s. Its onset is synchronous with the deposition of the Fröel Formation in
Gotland
Gotland (, ; ''Gutland'' in Gutnish), also historically spelled Gottland or Gothland (), is Sweden's largest island. It is also a province, county, municipality, and diocese. The province includes the islands of Fårö and Gotska Sandön to ...
. Perceived extinction in the
conodont
Conodonts ( Greek ''kōnos'', " cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, whi ...
fauna, however, likely represent a change in the depositional environment of sedimentary sequences rather than a genuine biological extinction.
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.
Notes
The Ireviken, Mulde, and Lau events were all closely followed by isotopic excursions.