First nuclear explosion helps test theory of moon's formation February 8, 2017 Please Register or Log in to view the hidden image! Professor James Day is in the Scripps Isotope Geochemistry Laboratory. Credit: Scripps Institution of Oceanography/UC San Diego Decades-old radioactive glass found blanketing the ground after the first nuclear test bomb explosion is being used by scientists to examine theories about the Moon's formation some 4.5 billion years ago. In a new study, Scripps Institution of Oceanography at the University of California San Diego Professor James Day and colleagues examined the chemical composition of zinc and other volatile elements contained in the green-colored glass, called trinitite, which were radioactive materials formed under the extreme temperatures that resulted from the 1945 plutonium bomb explosion. The test samples analyzed were collected between 10 meters (30 feet) and 250 meters (800 feet) from ground zero at the Trinity test site in New Mexico. When compared with samples collected farther away, the glass closest to the detonation site was depleted in volatile elements such as zinc. The zinc that was present was enriched in the heavier and less-reactive isotopes, which are forms of these elements with different atomic mass but the same chemical properties. Read more at: https://phys.org/news/2017-02-nuclear-explosion-theory-moon-formation.html#jCp
http://advances.sciencemag.org/content/3/2/e1602668 Evaporative fractionation of zinc during the first nuclear detonation: Abstract 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 α 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.
Pretty good evidence that the "Planetary Impact theory" of Lunar formation, is still the most viable.
