Catastrophic asteroid collision with Earth ahead of several large-scale volcanic eruptions in the fight for the title of the biggest killers of life on Earth. The breakthrough led to the re-surfaced two things: a collision that occurred 250 and 65 million years ago. The first mass extinction occurred at the boundary of the Triassic and Permian geological periods — then, according to fossil evidence, had died more than 90% of marine life forms and about 70% of the land. The second (and probably the most well-known) — on the border of the Cretaceous and Tertiary periods, it led to the extinction of the dinosaurs and most animals and plants co-exist with them.
Both events were accompanied by violent volcanic activity, so that many scholars have suggested that it is the volcanoes are the direct perpetrators of the death of the living. However, the discovery and analysis of the crater formed by a collision with an asteroid 65 million years ago, and meteorite fragments that emerged clearly in a collision with an asteroid 250 million years ago, have led many to believe that these events, not volcanism, are a major cause of extinctions. Two new studies support this hypothesis.
Asteroid impact can cause a catastrophe
In 1991, scientists found on the Mexican peninsula of Yucatan crater depth of 900 meters and a diameter of 180 kilometers, formed after the fall of the Earth giant comet or asteroid about 65 million years ago. Then it began to clash as the probable cause of extinction at the boundary of the Cretaceous and Tertiary periods.
Recently, a group of scientists led by Asish Basu, a geochemist at the University of Rochester in New York, found dozens of unusual mineral inclusions in two samples of rock taken from Graphite Peak (Graphite Peak) in Antarctica. According to them, these pieces — particles of meteorite that crashed into the Earth 250 million years ago. "We analyzed them and found out that the substance of extraterrestrial origin," — said Basu. The researchers also found particles of essentially pure metallic iron in the Antarctic rock — in their words, not earthly and extraterrestrial origin. Most of these particles are similar to the results in China (referring to the same time), which appears to have been formed during the condensation of clouds formed by an asteroid impact on earth.
At Graphite Peak was discovered, and the third (the most controversial) feature of a collision with a celestial body — clusters of carbon atoms in the form of balls. This gave Basu and his colleagues to claim that all of this material originated in a collision with a meteorite / asteroid that occurred on the border between the Permian and Triassic periods. Now Basu started looking crater, which could be produced at the event.
In another study of geochemistry at the University of Hawaii compared the ratio of two isotopes of osmium in seawater — the results of research led them to conclude that the rough work of the volcanoes on the border between the Cretaceous and Tertiary periods caused global warming, but hardly was the main cause of death of the dinosaurs.
This gives reason to believe that although the volcanic activity occurred during the collision, the peak of volcanism was a few hundred thousand years before the asteroid fell on the Yucatan Peninsula, causing a mass extinction.