Disproved the hypothesis that the end of the Ice Age Earth-snowball

Disproved the hypothesis that the end of the Ice Age''Земля-снежок''

Cliffs of the Yangtze River, where they found the samples dolomitita depleted in carbon-13. (Photo by M. Kennedy / UC Riverside.)

Rock on which the theory is based on how 600 million years ago, the ice age ended, actually formed much later and at a temperature so high that no living beings to them could not be connected. This is the conclusion a team of scientists led by researchers at the California Institute of Technology (USA).

Glaciation that covered almost the entire planet (hence the concept of "earth-snow"), interrupted quite suddenly. They say it was due to the large amount of methane emerging from the ocean and permafrost.

Basic physical evidence to support this theory, because the samples were obtained dolomitita (dolostone) from southern China, which contain much less carbon-13 than conventional representatives of this type of carbonate rocks. Experts have suggested that these rocks were formed when the rising methane oxidation ("eat") microorganisms in the Dolomites. The idea makes sense also because methane usually contains a low concentration of carbon-13, so if the methane gets into the breed, breed and really should contain less carbon-13. On the other hand, the hypothesis is controversial, because there is no other evidence of the presence in the carbonate rocks of the early Earth organisms fed with methane.

New research and do it denies. The scientists used a method developed by John Euler of the California Institute of Technology. It is dedicated to the analysis of the way in which rare isotopes (eg, carbon-13) are grouped together in crystalline structures. This grouping is strongly temperature dependent immediate environment: the higher it is, the less sticking, and vice versa.

It turned out that the source of carbon in the samples studied dolomitita not oxidized and turned into carbonate on the surface of the planet. This happened in a very hot environment deep in the earth, besides the millions or tens of millions of years after the end of the Ice Age.

"The next stage of research will be the question of why the carbonate rocks, poor carbon-13 and resulting seepage of methane was produced just 400 million years or so ago — said lead author John Grottsinger. — From the first three billion years of history has been preserved evidence of carbonates oxidation of methane — a very curious fact that the geological record. We believe that this may be due to changes in the chemistry of the ocean. "

The study is published in the journal Nature.

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