The End Ordovician Mass ExtinctionThis plot shows “extinction intensity”, defined as the
The End Ordovician Mass ExtinctionThis plot shows “extinction intensity”, defined as the fraction of genera that go extinct over a short time period. There are thought to be 5 major mass extinctions during the Phanerozoic, marked and labeled on this graph. The first of these on the list is the end-Ordovician.Because it is so long ago, scientists are still working to understand the cause. A new paper measured geochemistry of rocks crossing this boundary from what is today South China and found a pair of high-mercury layers at that boundary. One possibility is that this high mercury content represents the output from extremely active volcanoes, as is thought to be the driver of the end-Permian Mass Extinction (https://tmblr.co/Zyv2Js2OUCRsV). However, as of now there is no known “Large Igneous Province” at the time, leaving plenty more work to do to understand this extinction.-JBBImage credit:https://commons.wikimedia.org/…/File:Extinction_Intensity.s…Original paper:http://geology.geoscienceworld.org/content/45/7/631 -- source link
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