Séminaire IGE

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Sulfate triple-oxygen-isotope composition and its latest stories

jeudi 6 juillet 2023 - 11h00

Huiming Bao - Nanjing University
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In 1970s, Bob Clayton’s Chicago group discovered that the relative abundances of the three stable oxygen isotopes for many meteorites are different from those of Earth materials. In 1980s, Mark Thiemens’ UCSD group discovered that many oxygen-bearing gases in Earth’s atmosphere are anomalously enriched in the relative 17O abundance. The anomalous 17O enrichment was not noticed in Earth’s rock record until 2000. In 2008, at LSU, we found the first anomalous 17O depletion in Earth mineral, i.e., in sulfate deposits at the immediate aftermath of a Snowball Earth at ~635 million years ago. Today, we have recognized that these anomalous sulfate triple oxygen isotope signatures are widespread temporally and spatially in rock record. I will present two latest discoveries on this front: one case of sulfate positive 17O anomalies on recent weathering carbonate outcrops and one case of sulfate negative 17O anomalies on a large carbon isotope excursion at ~570 million years ago.

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Equipe organisatrice : Organisation labo

Salle Lliboutry, IGE Glaciologie, 38400 Saint Martin d'Hères