Onderzoeksbevinding: water in mantel Aarde niet afkomstig van ruimtemateriaal zoals kometen
1 September 2020
12:56
Earth’s building blocks may have had far more water than previously thought
Meteorites suggest that H2O in the mantle comes from local origins, contrary to expectations
Earth’s deep stores of water may have been locally sourced rather than trucked in from far-flung regions of the solar system.
A new analysis of meteorites from the inner solar system — home to the four rocky planets — suggests that Earth’s building blocks delivered enough water to account for all the H2O buried within the planet. What’s more, the water produced by the local primordial building material likely shares a close chemical kinship with Earth’s deep-water reserves, thus strengthening the connection, researchers report in the Aug. 28 Science.
Earth’s water may have been inherited from material similar to enstatite chondrite meteorites
An unexpected source of Earth’s water
The abundances of Earth’s chemical elements and their isotopic ratios can indicate which materials formed Earth. Enstatite chondrite (EC) meteorites provide a good isotopic match for many elements but are expected to contain no water because they formed in the hot inner Solar System. This would require Earth’s water to be from a different source, such as comets. Piani et al. measured hydrogen contents and deuterium/hydrogen ratios (D/H) in 13 EC meteorites (see the Perspective by Peslier). They found far more hydrogen than is commonly assumed, with D/H close to that of Earth’s mantle. Combining these data with cosmochemical models, they show that most of Earth’s water could have formed from hydrogen delivered by EC meteorites.
