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The Ocean's Oxygen Isotopes Deciphered: Combining Observations, Experiments and Models

The Ocean's Oxygen Isotopes Deciphered: Combining Observations, Experiments and Models

Objective

The isotopic composition of O in seawater is a fundamental property of Earth's oceans, key to paleoclimate reconstructions and to our understanding of the origin of water on Earth, the water-rock reactions that govern seawater chemistry, and the conditions under which life emerged. Despite more than five decades of research, the geologic history of seawater 18O/16O remains a topic of intense debate. Without exception, well-preserved 18O/16O records from marine precipitates reflect both the minerals' formation temperature, and the isotopic composition of seawater. This duality has prevented unique interpretation of a long-term secular trend, in which 18O/16O in sedimentary rocks (e.g., carbonates, cherts) has increased by ~15 ‰ since the Archean. Here I outline an inter-disciplinary research program to address this fundamental problem, which integrates new geochemical observations, laboratory experiments, and numerical models.

We will generate geologic records of 18O/16O in two previously untapped repositories: iron oxides and iron-bearing authigenic clays. Several characteristics of both, and preliminary results, suggest that these repositories hold the potential to settle the long-standing debate about seawater 18O/16O. We will determine the temperature dependence of mineral-water O isotope fractionation in laboratory experiments and observations of natural systems. We will experimentally test the resistance of these minerals to O isotope exchange under geologically-relevant conditions, with the aim of evaluating the potential for late-stage isotopic resetting. Finally, we will develop models of the marine O isotope cycle, which account for the processes that govern seawater 18O/16O over long timescales, and which will be used to provide a quantitative understanding of the new records. With these new insights, we will explore implications for the geologic history of seawater chemistry, atmospheric composition, climate and biology.
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Host institution

WEIZMANN INSTITUTE OF SCIENCE

Address

Herzl Street 234
7610001 Rehovot

Israel

Activity type

Higher or Secondary Education Establishments

EU Contribution

€ 1 490 596

Beneficiaries (1)

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WEIZMANN INSTITUTE OF SCIENCE

Israel

EU Contribution

€ 1 490 596

Project information

Grant agreement ID: 755053

Status

Ongoing project

  • Start date

    1 September 2018

  • End date

    31 August 2023

Funded under:

H2020-EU.1.1.

  • Overall budget:

    € 1 490 596

  • EU contribution

    € 1 490 596

Hosted by:

WEIZMANN INSTITUTE OF SCIENCE

Israel