Scientists find evidence that they challenge the theory of the origin of water on Earth

A team of researchers at Oxford University reveals important evidence regarding the origin of water on Earth. Using a rare type of metite stone known as enstatite chondrites, which have a composition similar to that of the early Earth (4.55 billion years ago), we discovered a source of hydrogen that is important for the formation of water molecules.

Importantly, they demonstrated that the hydrogen present in this material is intrinsic and not caused by contamination. This suggests that the materials that our planet was built were much more abundant than previously thought.

Findings supporting the theory that the formation of habitable conditions on Earth does not depend on the asteroids that hit Earth is published in the journal Icarus.

Without hydrogen, the building block of basic elements, it would not have been possible for our planet to develop the conditions that support life.

The origins of hydrogen on Earth, and even water, are highly debated on Earth, and many believe that the hydrogen needed during the first about 100 million years of Earth was supplied by asteroids from space. However, these new findings contradict this, suggesting instead that they have the hydrogen needed to make water from the time the Earth first formed.

The researchers analyzed the elemental composition of metite, known as LAR 12252, originally collected from the Antarctic. They used an elemental analysis technique called X-ray absorption near edge structure (XANES) spectroscopy on a diamond source synchrotron in Harwell, Oxfordshire.

Previous studies led by a French team have originally identified hydrogen traces in metstones within organic materials and amorphous portions of cartilage (mm-sized sphere objects of metstones). However, the rest was not explained. In other words, it was unclear whether hydrogen was native or terrestrial contamination.

The Oxford team suspected that a significant amount of hydrogen could be attached to the rich sulfur of metstone. Synchrotrons were used to illuminate a strong beam of X-rays on the structure of metstones to search for sulfur-containing compounds.

When the samples were first scanned, the team focused their efforts on the amorphous portion of cartilage where hydrogen was previously discovered.

However, when accidentally analysing the material just outside of one of these cartilage, which consists of a matrix of very fine (submicrometer) materials, the team discovered that the matrix itself is very rich in hydrogen sulfide. In fact, their analysis found that the amount of hydrogen in the matrix is ​​five times higher than the amount of non-crystalline intercepts.

In contrast, in other parts of metstone with signs of obvious cracks and signs of terrestrial pollution (such as rust), little or no hydrogen was present. This makes it very unlikely that hydrogen sulfide compounds detected by the team will be generated from ground sources.

Because the atoms were made of materials similar to the rocks of cartilage in enstatite, this suggests that by the time the forming planets were large enough to be struck by asteroids, they had accumulated enough hydrogen reserves to explain the current presence of Earth’s water.

Tom Barrett, a Dphil student at the Department of Earth Sciences at Oxford University, said he led the research.

“Because this hydrogen sulfide, which comes from terrestrial pollution, is very unlikely, this study provides important evidence to support the theory that water on Earth is native.

Co-author Associate Professor James Bryson (Oxford University Faculty of Earth Sciences) added:

“We now believe that the materials that built our planet (which can be studied using these rare metstones) were far more hydrogen-rich than we had previously thought. This finding supports the idea that the formation of water on Earth is a natural process rather than a hydrating asteroid vampire that fires the planet after it has been formed.”