New Evidence Shows Giant Meteorite Impacts Formed Parts of the Moon's Crust
upstart writes in with an IRC submission for Bytram:
New evidence shows giant meteorite impacts formed parts of the Moon's crust:
New research published today in the journal Nature Astronomy reveals a type of destructive event most often associated with disaster movies and dinosaur extinction may have also contributed to the formation of the Moon's surface.
A group of international scientists led by the Royal Ontario Museum has discovered that the formation of ancient rocks on the Moon may be directly linked to large-scale meteorite impacts.
The scientists conducted new research of a unique rock collected by NASA astronauts during the 1972 Apollo 17 mission to the Moon. They found it contains mineralogical evidence that it formed at incredibly high temperatures (in excess of 2300 C/ 4300 F) that can only be achieved by the melting of the outer layer of a planet in a large impact event.
In the rock, the researchers discovered the former presence of cubic zirconia, a mineral phase often used as a substitute for diamond in jewellery. The phase would only form in rocks heated to above 2300 C, and though it has since reverted to a more stable phase (the mineral known as baddeleyite), the crystal retains distinctive evidence of a high-temperature structure. An interactive image of the complex crystal used in the study can be seen here using the Virtual Microscope.
While looking at the structure of the crystal, the researchers also measured the age of the grain, which reveals the baddeleyite formed over 4.3 billion years ago. It was concluded that the high-temperature cubic zirconia phase must have formed before this time, suggesting that large impacts were critically important to forming new rocks on the early Moon.
Journal Reference
L. F. White, A. ernok, J. R. Darling, et al. Evidence of extensive lunar crust formation in impact melt sheets 4,330 Myr ago, Nature Astronomy (DOI: 10.1038/s41550-020-1092-5)
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