Fresh water may have been present on Earth for much longer than previously thought, scientists suggest

Fresh water may have been present on Earth for much longer than previously thought, scientists suggest
Fresh water may have been present on Earth for much longer than previously thought, scientists suggest

23,000 billion cubic meters of water alone! Today, the largest natural reservoir in the world is none other than Lake Baikal in southern Siberia.

But this astronomical quantity should not make us forget that fresh water from lakes, rivers, glaciers and other groundwater represents barely 2.5% of the volume of water on Earth, compared to 97.5% for salt water. (Water Information Center). A precious resource, therefore, and perhaps also older than we thought.

In any case, this is what a team who came to present their work at the European Geosciences Union conference in April (LiveScience) says. Among their peers, these scientists talked about crystal samples. More specifically, zircon fragments taken from the Jack Hills mountain range in Western Australia.

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This place undoubtedly revived memories among the assembly of researchers, since it was there that the oldest material identified to date on our planet had already been found: zircon, in fact, dated 4.4 billion years – or 200 million years less than the globe itself, which is 4.6 billion years old (NASA).

A crystal born from contact between magma and fresh water

The approximately 1,400 zircon samples newly analyzed by scientists dated back 4 billion years for the oldest. It is certainly more recent than the discovery which caused a lot of noise, but their composition would nevertheless contain a valuable clue to the formation of the continents.

This is because these zircons contain higher levels of light oxygen isotopes compared to the same crystals formed in salt water. According to the research team, this implies that this material probably came from the interaction between magma rising from the bowels of the Earth and fresh water.

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However, who says fresh water, necessarily says presence of continents, since without emerged support, point of hydrological cycle alternating precipitation and evaporation, they underlined (LiveScience).

If this work were to be confirmed, it would mean that our blue planet was adorned with land no later than 600 million years after its own birth, whereas we usually place this episode much later, there 3 billion years old.

As for the origin of the water from the primordial ocean which saw these rock masses rise towards the sky, it is difficult for the moment to decide between two hypotheses: the presence of H2O in the initial composition of the globe , or its arrival later aboard asteroids from far, far away in space.

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