Directory of RSS feeds

RSS feeds in the directory: 2798

Added today: 0

Added yesterday: 0

Company / Other

Mass extinction and volcanism

The scientific approach 25.07.2016 at 06:07

Site news

Legendary volcanic eruptions in various regions of the world today are considered guilty of four of five mass extinctions on Earth.

the Most significant episodes of the decay of life on our planet in different historical periods were attributed to falling asteroids, microbes produce gases or volcanic eruptions. The so-called big five mass extinction led to the extermination of most animals and plants on Earth, including the dinosaurs 66 million years ago. The new data clearly indicate a catastrophic eruption as the real culprits of extinction. High-precision Dating of rocks allows to correlate in time the disaster with four major extinctions and to link the eruption with a lethal change in the atmosphere, which will be illustrated next.

for Example, 251.9 million years ago, life stopped in the Permian. Then disappeared over 95% of marine and 70% terrestrial species. About the same period of time in the large igneous province of the Siberian traps occurred the great volcanic activity. To be sure, if geological activity before the extinction and could she become his reason, geochronology Seth Burgess (Seth Burgess) and Samuel Bowring (Samuel Bowring) from mit went with colleagues to Siberia for further geochronology.

the Scientists collected tiny crystals of zircon and perovskite from igneous rocks. During the formation of these crystals they have uranium, which constant speed is converted into lead when the cooling on the earth's surface, the ratio of uranium to lead shows how long ago outpouring. As mentioned in a report published in August 2015 in the journal Science Advances, most of the eruptions on the planet began 300 thousand years before the universal extinction reached the highest point. Geochemists also found indications of a rapid rise in carbon dioxide level — another consequence of the deadly eruption in the atmosphere of the time; a similar increase occurred in the species extinction in the late Devonian, Triassic and Cretaceous periods.

These eruptions are classified as extraordinary: emissions cover a huge field, sometimes stretching thousands of miles, plow up volcanic craters. Geologists call such areas of large igneous provinces (BMP). Today the remains of the eruptions form extensive fields of solidified lava in the remote areas of Asia and other places. The eruption of these large provinces were a breathtaking sight: magma rises into the atmosphere dazzling fountains km altitude, hot yellow lava flowed in long rivers, everywhere spread burning sulfur fog.

But the lava and ash caused mass extinction of species, this deadly spiral has spun gases of sulfur dioxide and carbon dioxide. Some new research data inspired Geophysics Mark Richards (Mark Richards) from the University of California, Berkeley, and geologist Walter Alvarez (Walter Alvarez), supporters of the asteroid theory of dinosaur extinction, to clarify its provisions. In April 2015 they published in the GSA Bulletin, the report suggested that the energy hitting Earth asteroid precipitated the most violent eruption in the Cretaceous period. Thus, study of volcanic activities strengthened the impact theory, which, unlike the dinosaurs, continues to live.


Source: In the world of science [07] 2016