Iron and zinc stable isotope evidence for open-system high-pressure dehydration of antigorite serpentinite in subduction zones
| العنوان: | Iron and zinc stable isotope evidence for open-system high-pressure dehydration of antigorite serpentinite in subduction zones |
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| المؤلفون: | Vicente López Sánchez-Vizcaíno, Pierre Bouilhol, B. Debret, Marie-Laure Pons, Carlos J. Garrido, Edward C. Inglis, Helen M. Williams |
| المساهمون: | Ministerio de Ciencia e Innovación (España), European Commission, Junta de Andalucía, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Williams, Helen [0000-0001-5837-1590], Apollo - University of Cambridge Repository, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD) |
| المصدر: | Digital.CSIC. Repositorio Institucional del CSIC instname Geochimica et Cosmochimica Acta Geochimica et Cosmochimica Acta, In press, 296, pp.210-225. ⟨10.1016/j.gca.2020.12.001⟩ Geochimica et Cosmochimica Acta, Elsevier, In press, ⟨10.1016/j.gca.2020.12.001⟩ |
| بيانات النشر: | Elsevier BV, 2021. |
| سنة النشر: | 2021 |
| مصطلحات موضوعية: | Peridotite, 010504 meteorology & atmospheric sciences, Mantle wedge, Stable isotope ratio, Chemistry, Geochemistry, Metamorphism, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, sub-05, Carbon cycle, Subduction, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Fe and Zn stable isotopes, Geochemistry and Petrology, Primitive mantle, Protolith, Metamorphic facies, 0105 earth and related environmental sciences, Serpentinite |
| الوصف: | Subducted serpentinites have the potential to control the exchange of volatile and redox sensitive elements (e.g., Fe, S, C, N) between the slab, the mantle wedge and the deep mantle. Here we examine the mobility of iron and zinc in serpentinite-derived fluids by using their stable isotopes (δFe and δZn) in high-pressure subducted meta-serpentinites from the Cerro del Almirez massif (Spain). This massif preserves a metamorphic front between antigorite (Atg-serpentinite) and antigorite-olivine-orthopyroxene (transitional lithologies) -bearing serpentinites, and chlorite-bearing harzburgite (Chl-harzburgite), displaying granofels, spinifex and fine-grained recrystallized textures. Those rocks were formed at eclogite facies conditions (1.6–1.9 GPa and 680–710 °C). The mean δFe of all the Cerro del Almirez meta-serpentinites (+0.05 ± 0.01‰) is identical within an error to that of primitive mantle (+0.03 ± 0.03‰). A positive correlation between δFe and indices of peridotite protolith fertility (e.g., AlO/SiO) suggests that the δFe values of Cerro del Almirez samples predominantly reflect protolith compositional variations, likely produced by prior episodes of melt extraction. In contrast, the Zn concentrations ([Zn] = 34–67 ppm) and isotope signatures (δZn = +0.18 – +0.55‰) of the Cerro del Almirez samples show a broad range of values, distinct to those of the primitive mantle ([Zn] = 54 ppm; δZn = +0.16 ± 0.06‰). The Atg-serpentinites ([Zn] = 34–46 ppm; δZn = +0.23 ± 0.06‰) display similar [Zn] and δZn values to those of slab serpentinites from other high-pressure meta-ophiolites. Both [Zn] and δZn increase in transitional lithologies ([Zn] = 45–67 ppm; δZn = +0.30 ± 0.06‰) and Chl-harzburgites with granofels ([Zn] = 38–59 ppm; δZn = +0.33 ± 0.04‰) or spinifex ([Zn] = 48–66 ppm; δZn = +0.43 ± 0.09‰) textures. Importantly, Cerro del Almirez transitional lithologies and Chl-harzburgites display abnormally high [Zn] relative to abyssal peridotites and serpentinites (29–45 ppm) and a positive correlation exists between [Zn] and δZn. This correlation is interpreted to reflect the mobilization of Zn by subduction zone fluids at high pressures and temperatures coupled with significant Zn stable isotope fractionation. An increase in [Zn] and δZn from Atg-serpentinite to Chl-harzburgite is associated with an increase in U/Yb, Sr/Y, Ba/Ce and Rb/Ce, suggesting that both [Zn] and δZn record the interaction of the transitional lithologies and the Chl-harzburgites with fluids that had equilibrated with metasedimentary rocks. Quantitative models show that metasediment derived fluids can have isotopically heavy Zn as a consequence of sediment carbonate dissolution and subsequent Zn complexation with carbonate species in the released fluids (e.g., [ZnHCO(HO)] or [ZnCO(HO)]). Our models further demonstrate that Zn complexation with reduced carbon species cannot produce fluids with heavy δZn signature and hence explain the δZn variations observed in the Chl-harzburgites. The most straightforward explanation for the heavy δZn of the Cerro del Almirez samples is thus serpentinite dehydration accompanied by the open system infiltration of the massif by oxidized, carbonate-rich sediment-derived fluids released during prograde subduction-related metamorphism. We thank G. Nowell (Durham University, UK) for technical support and K. Burton (Durham University, UK) for fruitful discussions. This work was supported by a Natural Environment Research Council (NERC) Deep Volatiles Consortium Grant (NE/M000303/1), a European Research Council (ERC) Starting Grant (HabitablePlanet; 306655) to H. Williams, and by the TelluS Program of CNRS/INSU. B Debret acknowledges financial support by LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX-0001). M. T. Gómez‐Pugnaire, J. A. Padrón-Navarta, and C. Marchesi are thanked for early work and characterization of the samples investigated in the present study. We are grateful to the Sierra Nevada National Park authorities for providing the permit for fieldwork and sampling at the Cerro del Almirez massif. E.I. is supported as a postdoc on an ERC Horizon 2020 advanced grant (SHRED; 833632) awarded to Dr. C. Chauvel (IPG, Paris). C.J.G. and V.L.S.-V. acknowledge funding from the “Spanish Ministry of Science and Innovation” and “Agencia Estatal de Investigación (AEI)” grants no. CGL2016-75224-R and CGL2016-81085-R, and from the “Junta de Andalucía” research group grants RNM-131 and RNM-374. We thank S.-A. Liu, R. Halama and two anonymous reviewers for critical comments on earlier version of this article and careful editorial handling by D.A. Ionov. |
| وصف الملف: | application/pdf |
| تدمد: | 0016-7037 |
| DOI: | 10.1016/j.gca.2020.12.001⟩ |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::bb6200efead3ffeb3008073b4f7dfbc3 http://hdl.handle.net/10261/278134 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....bb6200efead3ffeb3008073b4f7dfbc3 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 00167037 |
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| DOI: | 10.1016/j.gca.2020.12.001⟩ |