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A crashing crust could have turned the earth into a giant snowball



Today, the earth is a fairly temperate place, but about 700 million years ago, ice covered the planet from pole to pole, in an extreme glacial period often called "snowball earth." Scientists have proposed a whole range of theories for what could have frozen the world, and a new study has suggested that the root of all could be the beginnings of plate tectonics.

As inhabitants of the earth We have learned to accept that changing plates and earthquakes are just an unavoidable part of life. But this activity is the exception rather than the rule: Most other planets, except perhaps Mercury, are much quieter.

"The Earth is the only body in our solar system that is known to have plate tectonics, where the lithosphere is fragmented like puzzle pieces that move independently," says Robert Stern, co-author of the study. "It is much more common that planets have an outer solid shell that is not fragmented, known as" single-site tectonics. "

That did not happen on our planet. At some point in the distant past, the solid lid broke apart into plates that still move today. It is still in debate just when this transition took place, but it is generally believed that this monumental separation took place between 3 and 3.5 billion years ago. However, the new study suggests a much younger transition between 800 and 600 million years ago in the middle of the Neoproterozoic era. According to geologists at the University of Texas in Austin and Dallas, geological features previously associated with plate tectonics are only so far back, and the earth seems to have been relatively quiet about a billion years ago.

"If you look at the surviving records, the diagnostic evidence for modern plate tectonics, which involves deep subduction, is mainly Neoproterozoic and younger," says Nathaniel Miller, co-author of the study. "But most people think we have so much earlier in the Earth's history."

But there is another important piece of evidence for this revised timeline. A cataclysm like the Earth's crust, which breaks up and rearranges itself into smaller pieces, would undoubtedly have had global repercussions ̵

1; and the results would probably have looked similar to the Snowball Earth, which perfectly fits the newly proposed timeframe. [19659004] UT researchers collected 22 hypotheses previously proposed as mechanisms that cool the planet down to the snow-bale level, including volcanic eruptions, changes in the planet's axis of rotation, and rocks that pull more carbon dioxide out of the atmosphere.

The team believes that the beginnings of plate tectonics could be the cause of all these scenarios. The breakup would have increased the explosive arc volcanism and stimulated mantle clouds that would have flushed huge amounts of material into the atmosphere. In the meantime, the displacement plates could also cause the earth to wobble around its axis.

"We reviewed the literature and explored all the mechanisms proposed for Snowball Earth," says Stern. "The onset of plate tectonics could be responsible for any of these explanations." The fact that strong climatic and oceanographic effects are observed during the Neoproterozoic period is a strong supportive argument that this is indeed the time of the transition from single cell to plate tectonics is an argument that has not been considered to our knowledge yet. "

The researchers confirm that their proposal contradicts conventional thinking and that the possible link needs to be explored more closely. For example, the event Snowball Earth could only be the result of a period of increased tectonic activity, not just from the beginning.

The study was published in the journal Terra Nova . [19659013]! Function (f, b, e, v, n, t, s) {if (f.fbq) return; n = f.fbq = function () {n.CallMethod?
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