Articles | Volume 34, issue 6
https://doi.org/10.5194/ejm-34-645-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/ejm-34-645-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Iron oxidation state in serpentines and magnesian chlorites of subduction-related rocks
Université de Lyon, ENSL, UCBL, CNRS, LGL-TPE, 69007 Lyon,
France
Clémentine Fellah
Université de Lyon, ENSL, UCBL, CNRS, LGL-TPE, 69007 Lyon,
France
Catherine McCammon
Bayerisches Geoinstitut, University of Bayreuth, 95447 Bayreuth, Germany
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Rocks are brought to great depths and back to the Earth's surface by the tectonic processes that shape mountain ranges. Tiny mineral inclusions can record how deep rocks went. Quartz, a common mineral inclusion, was put in the laboratory at conditions that mimic those encountered at depths to about 100 km. A laser-based spectroscopy (Raman) was calibrated to read pressure from quartz inclusions in rocks and to unravel their deep travel.
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In this study, we applied geochemical tools to well-preserved ∼180-million-year-old marine mollusc shells from polar and mid-latitude seas. These results indicate that polar shells grew at temperatures of 8–18°C, while mid-latitude shells grew at temperatures of 24–28°C. These results, together with previously published data, raise concerns about the ability of climate models to predict accurate polar temperatures under reasonably high atmospheric CO2 levels.
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Mineral., 54, 252–265, https://doi.org/10.1346/CCMN.2006.0540210, 2006.
Short summary
Serpentines, magnesian clay-like minerals formed in subduction zones, contain iron in either ferrous or ferric form. The oxidation state of the iron form controls the composition of fluids that form when they are destabilized by heating. Results obtained here with Mössbauer spectroscopy are compared with X-ray spectroscopy and shown to be more reliable for serpentines and magnesium-rich chlorites. Fluids released by serpentines in subduction may be less oxidized than previously thought.
Serpentines, magnesian clay-like minerals formed in subduction zones, contain iron in either...
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