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DECODING EARTH’S OXYGENATION HISTORY AND THE CHEMICAL EVOLUTION OF PRECAMBRIAN SEAWATER - COUPLED Fe-Os ISOTOPE SIGNATURES IN BANDED IRON FORMATIONS

Friday March 6 - 11 AM (cancelled)

Toni Schulz
Dept. of Lithospheric Research, University of Vienna, Austria
Institut für Geologie und Mineralogie, University of Cologne, Germany

ABSTRACT: Iron formations (IF) are predominantly Precambrian rocks, recording oceanic iron removal due to the oxidation of dissolved Fe(II) to insoluble Fe(III). Understanding this iron removal is the key to evaluate the oxygenation history of the Early Earth. At the core of this understanding lies the discrimination of the Fe sources (amongst other elements) and the mechanisms which led to IF precipitation. Current models for their deposition are highly controversial and involve either continental or hydrothermal elemental sources, explaining oceanic Fe removal by either inorganic or biologically promoted Fe(II) oxidation.
We here present preliminary results of a study that aims to combine already established redox-sensitive and bioactive geochemical proxies (e.g., 56Fe) with the 187Re-187Os isotope system and highly siderophile element (HSE) abundances to study IFs. Both tools provide the potential to discriminate source contributions to IFs (continental, hydrothermal, meteoritic) and the assessment of redox conditions throughout Earth’s history.

BIO: Toni Schulz is a Senior Scientist at the Department of Lithospheric Research, University of Vienna, Austria. His research interests cover the chronology of the early solar system, the dynamics of the early solar nebula, planetary hability as well as early Earth's mantle-crust evolution and impact research. For this, he uses various short- and long-lived isotope systems, such as the Sr-Nd-Hf and Os isotope systems.

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