Formation and composition of Earth's Hadean protocrust

• 成果类型: Article
• 署名作者: Turner, Simon; Wood, Bernard; Johnson, Tim; O'Neill, Craig; Bourdon, Bernard
• 署名单位: Macquarie University; University of Oxford; Curtin University; Queensland University of Technology (QUT); Centre National de la Recherche Scientifique (CNRS); Ecole Normale Superieure de Lyon (ENS de LYON); Universite Claude Bernard Lyon 1
• 刊物名称: Nature
• ISSN/ISSBN: 0028-2931
• DOI: 10.1038/s41586-025-08719-3
• 发表日期: 2025-04-10
• 关键词: magma ocean; siderophile elements; continental-crust; missing niobium; oxidation-state; core formation; EVOLUTION; silicate; constraints; segregation

摘要

Although Earth, together with other terrestrial planets, must have had an early-formed protocrust, the chemical composition of this crust has received little attention. The protocrust was extracted from an extensive magma ocean formed by accretion and melting of asteroidal bodies1. Both experimental and chronological data suggest that the silicate melt ascending from this magma ocean formed in equilibrium with, or after, metal was extracted to form Earth's core. Here we show that a protocrust formed under these conditions would have had incompatible (with respect to silicate minerals) trace-element characteristics remarkably similar to those of the current average continental crust. This has major implications for subsequent planetary evolution. Many geochemical arguments for when and how plate tectonics began implicitly assume that subduction is required to produce the continental trace-element signature. These arguments are severely compromised if this signature was already a feature of the Hadean protocrust.