Gonzalo López SánchezSEGUIRMadrid Updated: Save Send news by mail electrónicoTu name *
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geologists know that in the past 540 million years ago the Earth has gone through at least five mass extinction events , in which volcanoes, asteroids, or the growth of some organisms led to a real biological collapse. These events occur when the biodiversity (the variety and distribution of species) and the abundance of organisms decreases dramatically and in a period of time, not very long, on the geological scale. Probably the most famous is the mass extinction of the Cretaceous-Tertiary, which ended with the reign of the dinosaurs and 75% of the species, largely due to the impact of a large meteorite.
But this has not been the most serious of all that have passed through living beings. Ago 251 million years ago extinction Permian-Triassic was about to erase the life from the face of the Earth. This event led to the disappearance of 96% of marine species and 83 for all genres in a period of a million years, for what, with reason, it is known this cataclysm as the “Great Slaughter” . During this unfortunate era, the oceans have reached steamy temperatures of 40 ° c at the Equator, and the planet suffered a profound global warming. It took millions of years for the living beings regain the lost ground.
it Is believed that this mass extinction was caused by one of the volcanic events most gigantic known: the eruption of the “Stairs Siberian”.
for two million years volcanoes were releasing lava, to cover about seven million square kilometers of surface, and huge quantities of noxious gases, some able to climb a 5 ° C global average temperature. But the signs point to that something more happened at that time to explain the extinction of so many species: we talk about the impact of an object extraterrestrial, of tectonic movements or of the mass release of clatratos of methane from the bottom of the oceans.
Extension of the lava released by the eruptions of the Stairs Siberian – Wikipedia
A study published this week in the journal “Geology” has shed more light on what happened during the mass extinction of the Cretaceous-Tertiary. A team of scientists from the University of the State of Arizona (U.S.) has provided the first direct evidence of another factor that could contribute to the global warming associated with this cataclysm: burning massive amounts of coal, materials rich in carbon and wood .
The researchers, led by Lindy Elkins-Tanton, traveled up the Stairs Siberia, where it is suspected that the lava did burn significant amounts of coal and vegetation. Thanks to an article previously published, they found an area, close to the river Angara , where it is piled up with interesting outcrops of rocks volcanoclásticas (formed by pieces of different origin during an eruption), in whose inside there are important clues as to what happened.
huelllas of the disaster
During six years the team has been traveling to that region to collect approximately 450 pounds of rocks. Steve Grasby, one of the co-authors of the work and researcher at the Geological survey of Canada, examined these specimens, and found indications of coal and wood burned the end of the Permian, the time in which occurred the “Great Slaughter”. In fact, the remains were consistent with what found in a previous investigation, in which Grasby found remains of charcoal and wood in the islands of the canadian Arctic, which are believed to come from the washing of the traces left by the eruptions of the Stairs Siberian.
A wall made entirely of rocks volcanoclásticas next to the river Angara in Siberia – Scott Simper
“Our study shows that the magmas of the Stairs Siberian incorporated carbon and organic material,” said Lindy Elkins-Tanton said in a statement. “That gives us a direct evidence that the magmas burned large amounts of coal and organic matter during the eruption”.
These clues support the hypothesis that the global warming of the Permian-Triassic was able to rely on the combustion of coal, carbonates, and shales rich in carbon, able to release high amounts of carbon dioxide (CO2) and methane (CH4) , both important greenhouse gases.
“The above observations are interpreted as evidence that the combustion of coal and organic matter, along with forest fires, occurred in response to the vulcanism”, are written by the authors of the study. Given that these traces of coal and wood burned have been found in the south and in the center of the region of the Stairs Siberian, believe that this phenomenon “was extensive” and that, therefore, could have a role “significant” in the “Great Slaughter”.
currently, some scientists have proposed that the planet is in the sixth great extinction , because of the annihilation of species caused by human activity. In addition, the evidence points to the existence of a global warming that has increased the average temperatures of 0.9 ºC in a little more than 100 years, a sigh in the geological scale, again because of the release into the atmosphere of significant amounts of greenhouse gases.