Earth's first glaciation at 2.9 Ga revealed by triple oxygen isotopes

A. Hofmann, I. N. Bindeman

Research output: Contribution to journalArticlepeer-review

Abstract

We here report the lowest (∼3 ‰ VSMOW) δ18O values for any weathering-related sedimentary rock in Earth's history, from shales and diamictites of the Mesoarchaean Pongola Supergroup of South Africa. This volcano-sedimentary succession was deposited in a shallow epeiric sea on continental crust of the Kaapvaal Craton and includes the record of the Earth's oldest surface glaciation. Oxygen isotope data of shales of the Mozaan Group indicate gradual climatic cooling of the surface environments that culminated in glacial conditions at ∼2.90 Ga. Mathematical inversion of measured Δ'17O and δ18O values results in δ18O values around -20 ‰ for weathering waters, suggesting cold climate conditions. These observations suggest continental weathering of the Kaapval Craton involving low δ18O meteoric waters, possibly in a near-polar position.

Original languageEnglish
Pages (from-to)20-24
Number of pages5
JournalGeochemical Perspectives Letters
Volume26
DOIs
Publication statusPublished - 2023

ASJC Scopus subject areas

  • Environmental Chemistry
  • Geology
  • Geochemistry and Petrology

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