New research from The University of Texas at Austin reveals that the Earth’s unique iron composition isn’t linked to the formation of the planet’s core, calling into question a prevailing theory about the events that shaped our planet during its earliest years.
Lin said that one of the most popular theories to explain the Earth’s iron signature is that the relatively large size of the planet (compared with other rocky bodies in the solar system) created high pressure and high temperature conditions during core formation that made different proportions of heavy and light iron isotopes accumulate in the core and mantle. This resulted in a larger share of heavy iron isotopes bonding with elements that make up the rocky mantle, while lighter iron isotopes bonded together and with other trace metals to form the Earth’s core.
But when the research team used a diamond anvil to subject small samples of metal alloys and silicate rocks to core formation pressures, they not only found that the iron isotopes stayed put, but that the bonds between iron and other elements got stronger. Instead of breaking and rebonding with common mantle or core elements, the initial bond configuration got sturdier..
Lin said it will take more research to uncover the reason for the Earth’s unique iron signature, and that experiments that approximate early conditions on Earth will play a key role because rocks from the core are impossible to attain. Paper. (public access) – Jin Liu, Nicolas Dauphas, Mathieu Roskosz, Michael Y. Hu, Hong Yang, Wenli Bi, Jiyong Zhao, Esen E. Alp, Justin Y. Hu, Jung-Fu Lin. Iron isotopic fractionation between silicate mantle and metallic core at high pressure. Nature Communications, 2017; 8: 14377 DOI: 10.1038/ncomms14377More.
Hey, they’re probably not even rocks, right? Liquid, they say.
See also: Atheist cosmologist warns “deeply religious” people not to put their faith in “apparent” fine-tuning
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