A trace gas analysed in mineral spring water in Germany gives clues on the origins of the Earth
Researchers supported by the ERC have sampled magmatic gases derived from the Earth's mantle in the Eifel region in Germany. Their analysis of xenon, a rare and inert gas, sampled in bubbling mineral water could bring new insights into the origin of volatile elements, water and gases, that allowed life to develop on Earth.
How the Earth formed about 4.54 billion years ago remains quite enigmatic. Because of their multiple isotopes (or forms) of various origins, noble gases stored in the Earth's mantle are used by researchers to trace the physical processes that took place within the Earth's various layers at this time.
Noble gases from the Earth's interior are, however, very difficult to analyse. Colourless, odourless, tasteless and non-flammable, these chemical elements are extremely rare. This makes them easily contaminated by the atmosphere, and challenging to measure with precision.
The discovery of fossil noble gases in the mineral spring water of Viktoriaquelle in southwest Germany has provided an excellent opportunity to examine the factors that influenced the Earth's formation. This sparkling CO2-rich water is situated in the Eifel volcanic region. Previous studies have shown that carbon dioxide bubbling in this well originates in the underlying terrestrial mantle.
In a paper published online in Nature on 25 April, a research team, including ERC Advanced grantee Prof. Bernard Marty, from the Centre de Recherches Petrographiques et Geochimiques (France), reports to have succeeded in separating xenon, the heaviest noble gas, from other gases in collected samples. The researchers then measured the abundance of xenon and its isotopic composition with a state-of-the-art spectrometer.
The team have discovered that xenon was brought to Earth by extra-terrestrial bodies similar to asteroids, whose remnants are now located between Mars and Jupiter. As xenon found in the atmosphere originates from a different unidentified source, possibly from comets, these findings suggest that at least two types of sources contributed to the formation of volatile elements on Earth. Additionally, the researchers have calculated that the sampled gas is very old, dating back as far as 4.45 billion years ago.
This study has also confirmed that a mantle plume (i.e. upwelling of abnormally hot rocks from the deepest region of the Earth's mantle that builds major volcanic edifices such as the Hawaiian Islands or Iceland,) is responsible for volcanism in Southwest Germany.
Prof. Marty received ERC funding for the 5-year NOGAT project in 2011. He was recently selected for a second Advanced Grant under the EU’s Horizon 2020 programme.
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