The Lau event
The last and severest Silurian crisis, with turnover rates matching the great mass extinctions.
- When
- Known to
- ± 2 million years
- Era
- Silurian, Paleozoic
About 420 million years ago the Lau event brings faunal turnover otherwise seen only in the 'big five' extinctions, together with a huge carbon isotope excursion and a return of microbial seafloor communities. Cooling appears to have driven stronger upwelling, delivering nutrients that expanded anoxia from deep basins onto the shelves. It is a case of cooling, rather than warming, intensifying ocean anoxia.