High-precision analysis of noble gases showed that particles of the solar wind were trapped in the Earth’s core more than 4.5 billion years ago. Researchers at the Institute of Earth Sciences at the University of Heidelberg have concluded that particles have penetrated the overlying stone mantle for millions of years.
Scientists have discovered solar noble gases in the studied iron meteorite. Because of their chemical composition, such meteorites are often used as natural models for the Earth’s metalcore. The rare class of iron meteorites accounts for only 5% of all known meteorites found on Earth. Most are fragments of larger asteroids that formed metal cores in the first 1-2 million years of our solar system.
The Washington County iron meteorite, now being studied at the Klaus Cheer Space Chemistry Laboratory at the Institute of Earth Sciences, was discovered nearly 100 years ago. Its name comes from the name of the place in Colorado (USA) where it was discovered. It resembles a metal disc, is 6 cm thick and weighs about 5.7 kg.
Researchers were finally able to conclusively prove the presence of a solar component in an iron meteorite. Using a noble gas mass spectrometer, they determined that the Washington County meteorite samples contained noble gases, the isotopic ratios of helium and neon, that are typical of the solar wind.
The measurements had to be extremely accurate to distinguish solar signatures from dominant cosmogenic noble gases and atmospheric pollution, according to Dr. Manfred Vogt, a member of the Trieloff team. The team says that solar wind particles in the original solar system were captured by precursor materials from the parent asteroid in Washington County. The noble gases trapped along with the particles dissolved in the liquid metal, from which the asteroid’s core was formed.
The results of their measurements allowed the researchers to conclude that the core of the planet Earth may also contain such components of the noble gas. Another scientific observation confirms this assumption. Professor Triloff’s research team has long been engaged in measuring the isotopes of the noble gases helium and neon in the volcanic rocks of oceanic islands such as Hawaii and Reunion. These magmatites originate from a special form of volcanism originating from mantle plumes, rising from a depth of thousands of kilometers in the Earth’s mantle. Their particularly high content of solar gas distinguishes them from the shallow mantle, represented by the volcanic activity of submarine mid-oceanic mountain ranges.
These results appear to support the assumption that solar noble gases in the mantle plumes originate from the planet’s core and therefore denote solar wind particles from the center of the Earth. In principle, just 1-2% of metal with the same composition as the Washington meteorite in the Earth’s core would be enough to explain the various gas signatures in the mantle. Therefore, the Earth’s core can play a previously underestimated active role in the geochemical development of the Earth’s mantle.