Paleoproterozoic increase in zircon δ18O driven by rapid emergence of continental crust

C. J. Spencer, C.A. Partin, C.L. Kirkland, T. D. Raub, J. Liebmann, R.A. Stern

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Numerous geologic proxies for Earth system processes track dramatic changes at the atmosphere-lithosphere or atmosphere-ocean interface during the early Paleoproterozoic Era. The presence of a geodynamic driver for these changes and how this might have affected the deeper lithosphere is more cryptic. Here we present temporally constrained δ18O and εHf in detrital zircon from Paleoproterozoic sedimentary successions in Western Australia and Canada that chart a rapid change in the oxygen isotopic composition from <7.5‰ prior to Great Oxidation Event (GOE) to 9–11‰ by ∼2.3 Ga. Intriguingly, we show that the timing of this zircon δ18O isotopic shift directly coincides with the GOE and the rapid development of continental freeboard evidenced by the shift from predominantly subaqueous to subaerial large igneous provinces and a rapid decrease in Δ17O in shale. Importantly, no correlation exists between zircon δ18O and εHf or to known periods of enhanced tectonic reworking of sedimentary material (e.g. ∼2.3–2.2 Ga tectono-magmatic lull). We propose that the development of continental freeboard led to the appearance of an isotopically distinct sedimentary reservoir with high δ18O that was incorporated into subduction zone magmas. The sedimentary contamination of subduction zone magmas led to a globally rapid change in average continental composition as recorded by δ18O in zircon grains.
Original languageEnglish
Pages (from-to)16-25
Number of pages10
JournalGeochimica et Cosmochimica Acta
Volume257
Early online date24 Apr 2019
DOIs
Publication statusPublished - 15 Jul 2019

Keywords

  • Great Oxidation Event
  • Zircon
  • Oxygen isotopes
  • Proterozoic
  • Continental lithosphere

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