Evaporative fractionation of zinc during the first nuclear detonation

James Day (1, 2) , Frédéric Moynier (1) , Alex P Meshik (3) , Olga V Pradivtseva (3) , Donald R Petit

1 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
2 SIO - UC San Diego - Scripps Institution of Oceanography
3 WUSTL - Washington University in Saint Louis

Volatile element and compound abundances vary widely in planets and were set during the earliest stages of solar system evolution. Experiments or natural analogs approximating these early conditions are limited. Using silicate glass formed from arkosic sands during the first nuclear detonation at the Trinity test site, New Mexico, we show that the isotopes of zinc were fractionated during evaporation. The green silicate glasses, termed "trinitite," show +0.5 ± 0.1‰/atomic mass unit isotopic fractionation from~200 m to within 10 m of ground zero of the detonation, corresponding to an a fractionation factor between 0.999 and 0.9995. These results confirm that Zn isotopic fractionation occurs through evaporation processes at high temperatures. Evidence for similar fractionations in lunar samples consequently implies a volatile-depleted bulk Moon, with evaporation occurring during a giant impact or in a magma ocean.

Keywords: POTASSIUM; ABUNDANCES; MANTLE; ISOTOPIC EVIDENCE; WATER; ORIGIN; DIFFERENTIATION

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]; Earth and Planetary Astrophysics [astro-ph.EP]

James Day, Frédéric Moynier, Alex P Meshik, Olga V Pradivtseva, Donald R Petit. Evaporative fractionation of zinc during the first nuclear detonation. Science Advances , 2017, 3 (2), pp.e1602668. ⟨10.1126/sciadv.1602668⟩. ⟨insu-02612830⟩