Could Earth have had an even more violent infancy than previously imagined? New isotope data suggest that the Earth not only had a very violent beginning but also point to new information about our planets chemical evolution.
New and precise measurements of a neodymium isotope ratio (142Nd/144Nd) led Maud Boyet and Rick Carlson of Carnegie Institutions Department of Terrestrial Magnetism to the discovery that all terrestrial rocks have an excess of 142Nd compared to the expected building blocks of the planet. The results will appear in the June 16, 2005 edition of Science.
Prior research suggested that the Earth formed by the accumulation of planetesimals -- small cold bodies present in early solar system history. The chemical composition of these early bodies is reflected today in a type of stony meteorite called chondrites. Scientists had expected that the Earth would have a composition similar to these meteorites. However, this new research challenges these earlier conclusions by showing that terrestrial rocks have excess 142Nd caused by the radioactive decay of the now extinct isotope 146Sm.
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