Emergence of modern continental crust about 3 billion years ago

Bruno Dhuime, Andreas Wuestefeld, Chris J. Hawkesworth

Research output: Contribution to journalArticle (Academic Journal)peer-review

189 Citations (Scopus)

Abstract

The continental crust is the principal record of conditions on the Earth during the past 4.4 billion years. However, how the continental crust formed and evolved through time remains highly controversial. In particular, the composition and thickness of juvenile continental crust are unknown. Here we show that Rb/Sr ratios can be used as a proxy for both the silica content and the thickness of the continental crust. We calculate Rb/Sr ratios of the juvenile crust for over 13,000 samples, with Nd model ages ranging from the Hadean to Phanerozoic. The ratios were calculated based on the evolution of Sr isotopes in the period between the T DM Nd model age and the crystallization of the samples analysed. We find that the juvenile crust had a low silica content and was largely mafic in composition during the first 1.5 billion years of Earthâ €™ s evolution, consistent with magmatism on a pre-plate tectonics planet. About 3 billion years ago, the Rb/Sr ratios of the juvenile continental crust increased, indicating that the newly formed crust became more silica-rich and probably thicker. This transition is in turn linked to the onset of plate tectonics and an increase of continental detritus into the oceans.

Original languageEnglish
Pages (from-to)552-555
Number of pages4
JournalNature Geoscience
Volume8
Issue number7
Early online date22 Jun 2015
DOIs
Publication statusPublished - 2 Jul 2015

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