The young age of Earth

Patterson (1956) established that the age of Earth is close to that of meteorites. Over the last 20 years, workers argued for younger age for core differentiation based on Pb-Pb model ages and tungsten isotopic data and for gas retention based on I-Xe modeling. However, disagreement is abundant, and the young age of Earth has not been widely accepted. In this work, I examine all radiogenic noble gases in the atmosphere and use a model-independent approach and total inversion to show that (1) the Xe-closure age of Earth is 109 6 23 million years younger than the formation of meteorite Bjurbole (;4560 Ma) and (2) all radiogenic components of noble gases in the atmosphere can be quantitatively accounted for by production and degassing ;60% of the bulk silicate earth. The agreement between the I-Xe clock and Pu-UXe-Xe-Xe-Xe clock suggests that the volatility of iodine does not affect the I-Xe clock. Earth’s Xe-closure age is 4.45 6 0.02 Ga, consistent with the model age of Pb and the Sm-Nd, Sm-Nd and Hf-W systematics. On the basis of the consistency of these ages, 4.45 6 0.02 Ga probably represents the time when the last Martian-sized planetesimal hit Earth and reinitialized the global clocks. Copyright © 1998 Elsevier Science Ltd