Mercury (Hg) in Ryugu particles and implications for the origin of volatile elements in early Earth

Abstract Solar system abundances of the elements, which are determined by spectroscopic measurements of the solar photosphere and laboratory analyses of CI (Ivuna-type) carbonaceous chondrites, are a cornerstone to understand the origin and evolution of planets and other constituents, such as asteroids and comets. Mercury (Hg) is one of the elements whose solar system abundance is still poorly constrained due to no observable lines for Hg in the solar spectrum and large variations of the Hg abundance in CI chondrites caused by mainly terrestrial contamination. Here we determined elemental abundances including Hg for uncontaminated CI-like material from asteroid Ryugu by the Hayabusa2 spacecraft. The new solar system abundance of Hg is 0.907±0.108 atoms/106 Si atoms. Our results demonstrate that Hg in bulk silicate Earth originated from the addition of chondritic material after core formation, late sulfide segregation and/or degassing, and volatile elements are depleted in late-accreted materials relative to CI chondrites.