Ancient minerals reveal the harsh climate on the continents

A new study of ancient minerals called zircon shows that once existed a harsh climate, perhaps destroying the surface of the new continents formed on Earth.

Zircon - the oldest material on earth - is present on Earth from 4.4 billion years ago when our planet was only 150 million years old. According to the University of Wisconsin-Madison geologist John Valley, because zircon crystals are particularly stable for chemical changes, they become the gold standard for dating ancient rocks.

Earlier Valley used these tiny mineral particles, even smaller than a particle of dust, to prove that the continents and liquid water formed on the surface of the earth much earlier than everyone thought. about 4.2 billion years ago.

In a new article published online in Earth and Planetary Science Letters, a group of scientists led by geologist Takayuki Ushikubo, Valley and Noriko Kita of the University of Wisconsin - Madision proved that continents and Liquid water existed at least 4.3 billion years ago and was subjected to intense weather due to the harsh climate.

The time chart depicts the geological context that formed Jack Hills zircon - an ancient mineral formed when the earth was less than 500 million years old.(Artwork: Andree Valley)

Ushikubo - the first author of the study - says that the weather in the atmosphere provides the answer to the long-standing question in geology: why can't any form of rock be found within the first 500 million years after the earth was formed.

He said: 'Currently there are no more rock samples left before 4 billion years ago. Some see this as evidence of the existence of high temperatures at the ancient time of the earth. ' Previously, this phenomenon was explained by the hypothesis that meteorite destroyed the surface of the earth or the possibility that the earth existed in the form of red hot lava that rock could not form.

Today's analysis opens a completely different perspective.

Ushikubo and colleagues used a complex means called ion detecting microphones to analyze isotopic ratios of the element lithium in zirconic minerals on Jack hill in western Australia. By comparing the chemical mark with the lithium component in zircon in the continental crust and primitive rock layer similar to the earth's man-ti shell, they found evidence that the young planet has formed. The continent, had relatively cool temperatures as well as having water at the time of mineral zircon in Australia.

Jack Hills, Australia.(Photo: www.geology.wisc.edu )

Ushikubo said: '4.3 billion years ago, the earth had a suitable environment for living.' The vestige of lithium in zirconium also showed that the rock appeared on the surface of the earth but was weathered and watery. break down, this is determined by a heavy lithium isotope. 'The weather has formed on the surface of the continental crust or on the ocean floor, but the observed lithium component is only formed in the continental crust. ' The results demonstrate that perhaps the widespread pattern of weather has destroyed the first layer of earth on earth.

The oldest zirconium crystal is available on Earth 4.4 billion years ago.
(Photo: www.geology.wisc.edu )

Valley said: 'Wide-ranging weather formed over 4 billion years ago brings a lot of meaning. People have doubted this but have never obtained any direct evidence. ' Carbon dioxide in the atmosphere can combine with water to form carbonic acid falling into acid rain. The newly formed Earth's atmosphere is thought to contain an extremely high proportion of carbon dioxide, perhaps 10,000 times higher than this day.

Valley said: ' At that rate, we will have extremely harsh acid rain and a tremendous greenhouse effect. This condition dissolves rock. If granite is on the surface of the earth, they will be destroyed almost immediately if geologically, what we can identify in ancient times is zircons' minerals.

Other authors of the study include Aaron Cavosie of Puerto Rico University, Simon Wilde of the Australian Curtin University of Technology and Roberta Rudnick of the University of Maryland.