An international team of researchers has identified traces of the material that made up the protoplanet – the predecessor of Earth, that existed before the Moon formed, and therefore before the collision with the hypothetical Theia.
This substance was discovered in ancient rocks in Greenland, Canada and South Africa. To analyze (mafic) basalts, samples were collected from the Isua crystal complexes in Greenland, the Nuvvuagittuq greenstone belt in Canada, and the Kaapvaal Craton in South Africa. Modern basalts from Reunion Island and the Hawaiian Islands were also sampled.
As a result, scientists discovered a deficiency of the potassium isotope ⁴⁰K. This isotope deficiency suggests there was a “deep reservoir” of material in the Earth's crust that formed the protoplanet. Comparing the data with mixing models, the researchers concluded that about 25% of the potassium in the mantle is of extraterrestrial origin. These results confirm the presence of unmixed zones of primary mantle that continue to influence modern volcanic processes.
