A team of U.S. scientists found that, each repetitive cycle of 60 million years, biodiversity of our planet greatly decreases, approaching the limits of extinction. Strange extinction cycle would have started about 500 million years ago, driven by a geological phenomenon which moves from deep ocean crust affects the variety of plant and animal species.
The key to finding the mysterious phenomenon is the isotope strontium-87, according to Adrian Melotte physicist at the University of Kansas, USA. This is one of four stable isotopes of the element strontium, although less frequently (7%) than strontium-86 and strontium-88.
Researchers Richard Bambach, D.Petersen Kenna and John M. McArthur, found that the fossils of marine creatures of Sr-87 concentration compared with the Sr-86 increases every 60 million years, consistent with extinction waves.
According to Professor Mellot, the only way to strontium-87 is produced in nature is the radioactive decay of the element rubidium.
It is known that rubidium is present in igneous rocks from the crust, so traces of strontium-87 indicates that something happened with igneous rocks every 60 million years: an event resulting in massive erosion of these rocks and thus reach the ocean large amounts of Sr-87, which is kept in marine fossils.
Researchers are advancing the idea that tectonic movements of the continents rough ground causes increase in some regions; igneous rocks exhibit a phenomenon more intense erosion, but also lead to lower depth ocean waters, especially in coastal areas, causing extinction of many species.
The frequency of the phenomenon leads researchers to advance the idea of a “pulse of the Earth”” caused by convection processes within the planet but it is a little understood phenomenon which intrigues the researchers.”