A study suggests that Earth's crust in the Hadean eon, more than 4 billion years ago, was more similar to the modern continental crust than previously thought, with implications for the timing of habitable conditions on Earth. To uncover the origins of life and continental crust on Earth, researchers must decipher the nature of the planet's crust during the Hadean eon, which ended 4 billion years ago. Previous studies of the Hadean crust have suggested a composition rich in iron, similar to the current oceanic crust, whereas more recent studies point to compositions rich in silica and potassium, similar to the current continental crust. However, researchers have suggested that the existence of a high-silica crust may be an artifact of contamination. To resolve the composition of the early crust, Patrick Boehnke and colleagues examined the ratio of strontium isotopes in crystals of apatite preserved within Hadean-age rocks from Canada. The authors report that the ratio of strontium-87 to strontium-86 preserves the isotope ratio from the time of the crystals' formation and is indicative of the amount of silica present in the rocks at the time. The results suggest the existence of a silica-rich crust at around 4.2 billion years ago, suggesting that the crust had evolved its composition through several partial melts from previous iron-rich rocks. According to the authors, the composition suggests that early Earth could form a continental crust within 350 million years of solar system formation.
Article #17-20880: "Potassic, high-silica Hadean crust," by Patrick Boehnke et al.
MEDIA CONTACT: Patrick Boehnke, University of Chicago, IL; e-mail: <pboehnke@gmail.com>
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