Titre
Multistage hydration during oceanic serpentinisation revealed by in situ oxygen isotope and trace element analyses
Type
article
Institution
UNIL/CHUV/Unisanté + institutions partenaires
Périodique
Auteur(s)
Vesin, Coralie
Auteure/Auteur
Rubatto, Daniela
Auteure/Auteur
Pettke, Thomas
Auteure/Auteur
Deloule, Etienne
Auteure/Auteur
Liens vers les personnes
Liens vers les unités
ISSN
0016-7037
Statut éditorial
Publié
Date de publication
2023-08
Volume
355
Première page
13
Dernière page/numéro d’article
31
Peer-reviewed
Oui
Langue
anglais
Résumé
Serpentinisation of mantle peridotites below the seafloor is the most important hydration reaction in the Earth's deep water cycle. This critical step in water–rock interaction occurs over multiple serpentinisation stages and at variable temperatures and fluid compositions. We present the first study using spatially coupled in-situ analysis of oxygen isotopes (secondary ionization mass spectrometry) and trace elements (laser ablation inductively coupled plasma mass spectrometry) to unravel the multistage hydration history of oceanic serpentinites. We study samples from the Newfoundland-Iberia extended passive margins, which represents a magma-poor ocean-continent transition zone (Ocean Drilling Program cores, Leg 173 Site 1070 from Iberia, Leg 210 Site 1277 from Newfoundland). The concentrations of the fluid mobile elements chlorine and boron in serpentine are used as a proxy for the salinity of the serpentinising fluid. The correlation of Cl/B with δ18Oserpentine compositions provides new insights to disentangle temperature from fluid composition effects. The transition metal composition (V, Co, Sc, Mn, Zn, Ni, Cr) of dominantly lizardite in mesh after olivine and in bastite after orthopyroxene shows a chemical redistribution between textural sites in the Newfoundland samples, indicating the simultaneous serpentinisation of olivine and orthopyroxene. This feature is not observed in the Iberian samples, for which we propose sequential reactions. Lizardite in samples from both localities varies considerably in oxygen isotope composition at the scale of tens of micrometres depending on texture, with a range in δ18O of 3.3–13.5‰ for Iberia samples and a more restricted range of 5.7–9.3‰ for Newfoundland samples. Temperatures calculated from the δ18Oserpentine corresponding to the lowest Cl/B ratio (interpreted as closest to seawater composition) indicate sequential serpentinisation with decreasing temperature from ∼190 to ∼60 °C in the Iberia setting. The Newfoundland samples were serpentinised at a lower temperature (100–130 °C), possibly at a shallower depth. Serpentinisation in the Newfoundland samples probably produced a concentrated amount of H2 in a shorter period of time, whereas in the Iberian samples a small but prolonged amount of H2 was produced, possibly creating more favourable conditions for microbial activity.
Sujets
PID Serval
serval:BIB_E81E1D9C40CE
Open Access
Oui
Date de création
2023-09-01T10:24:03.426Z
Date de création dans IRIS
2025-05-21T06:02:07Z
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Nom
1-s2.0-S0016703723003058-main.pdf
Version du manuscrit
published
Licence
https://creativecommons.org/licenses/by/4.0
Taille
18.42 MB
Format
Adobe PDF
PID Serval
serval:BIB_E81E1D9C40CE.P001
URN
urn:nbn:ch:serval-BIB_E81E1D9C40CE8
Somme de contrôle
(MD5):0865436e79f76b80c6534346c19a1e27