Selenium isotope evidence for progressive oxidation of the Neoproterozoic biosphere

Philip A E Pogge von Strandmann*, Eva E. Stüeken, Tim Elliott, Simon W Poulton, Carol M. Dehler, Don E. Canfield, David C Catling

*Corresponding author for this work

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

52 Citations (Scopus)
298 Downloads (Pure)

Abstract

Neoproterozoic (1,000-542 Myr ago) Earth experienced profound environmental change, including â €' snowballâ €™ glaciations, oxygenation and the appearance of animals. However, an integrated understanding of these events remains elusive, partly because proxies that track subtle oceanic or atmospheric redox trends are lacking. Here we utilize selenium (Se) isotopes as a tracer of Earth redox conditions. We find temporal trends towards lower λ82/76 Se values in shales before and after all Neoproterozoic glaciations, which we interpret as incomplete reduction of Se oxyanions. Trends suggest that deep-ocean Se oxyanion concentrations increased because of progressive atmospheric and deep-ocean oxidation. Immediately after the Marinoan glaciation, higher λ82/76 Se values superpose the general decline. This may indicate less oxic conditions with lower availability of oxyanions or increased bioproductivity along continental margins that captured heavy seawater λ82/76 Se into buried organics. Overall, increased ocean oxidation and atmospheric O 2 extended over at least 100 million years, setting the stage for early animal evolution.

Original languageEnglish
Article number10157
Number of pages10
JournalNature Communications
Volume6
DOIs
Publication statusPublished - 18 Dec 2015

Keywords

  • Earth sciences
  • Biogeochemistry
  • Climate science
  • Geology and geophysics

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