Articles | Volume 15, issue 9
https://doi.org/10.5194/se-15-1143-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-15-1143-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Magnesium isotope fractionation processes during seafloor serpentinization and implications for serpentinite subduction
Sune G. Nielsen
CORRESPONDING AUTHOR
NIRVANA Labs, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA, USA
Department of Geology and Geophysics, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA, USA
Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, 54501 Vandoeuvre-lès-Nancy, France
Frieder Klein
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA, USA
Horst R. Marschall
Institut für Geowissenschaften, Goethe Universität Frankfurt, Frankfurt am Main, Germany
Philip A. E. Pogge von Strandmann
Institute of Geosciences, Johannes Gutenberg University, 55122 Mainz, Germany
Maureen Auro
NIRVANA Labs, Woods Hole Oceanographic Institution, 02543 Woods Hole, MA, USA
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This preprint is open for discussion and under review for Biogeosciences (BG).
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Subject area: Tectonic plate interactions, magma genesis, and lithosphere deformation at all scales | Editorial team: Geochemistry, mineralogy, petrology, and volcanology | Discipline: Geochemistry
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Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean
Bromine speciation and partitioning in slab-derived aqueous fluids and silicate melts and implications for halogen transfer in subduction zones
Boninite and boninite-series volcanics in northern Zambales ophiolite: doubly vergent subduction initiation along Philippine Sea plate margins
Veronica Peverelli, Alfons Berger, Martin Wille, Thomas Pettke, Pierre Lanari, Igor Maria Villa, and Marco Herwegh
Solid Earth, 13, 1803–1821, https://doi.org/10.5194/se-13-1803-2022, https://doi.org/10.5194/se-13-1803-2022, 2022
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This work studies the interplay of epidote dissolution–precipitation and quartz dynamic recrystallization during viscous granular flow in a deforming epidote–quartz vein. Pb and Sr isotope data indicate that epidote dissolution–precipitation is mediated by internal/recycled fluids with an additional external fluid component. Microstructures and geochemical data show that the epidote material is redistributed and chemically homogenized within the deforming vein via a dynamic granular fluid pump.
Renyu Zeng, Mark B. Allen, Xiancheng Mao, Jianqing Lai, Jie Yan, and Jianjun Wan
Solid Earth, 13, 1259–1280, https://doi.org/10.5194/se-13-1259-2022, https://doi.org/10.5194/se-13-1259-2022, 2022
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In the Liaodong Peninsula, the widely exposed Jurassic high-Sr / Y rocks are generally considered to be derived from the thickened mafic crust. However, research on the Zhoujiapuzi granite in this study shows that there is at least one pluton with a high Sr / Y signature inherited from the source. Zircon growth in Zhoujiapuzi granite can be divided into two stages. The light-CL core was formed in a deeper, hotter magma chamber. The dark-CL rim formed from later, more evolved magma.
J. Javier Álvaro, Teresa Sánchez-García, Claudia Puddu, Josep Maria Casas, Alejandro Díez-Montes, Montserrat Liesa, and Giacomo Oggiano
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A geochemical comparison of early Palaeozoic felsic magmatic episodes throughout the south-western European margin of Gondwana is analysed and includes data from the Iberian Massif, the Eastern Pyrenees, southern France and Sardinia. This dataset favours partial melting of sediments and/or granitoids in the lower continental crust during extensional movements related to the opening of the Rheic Ocean.
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Here, we conducted spectroscopic measurements on high-pressure, high-temperature fluids and melts to study how halogens, in particular bromine, can be incorporated in subduction zone fluids and melts. We find that a gradual evolution of bromine speciation with liquid composition enables the incorporation of high amounts of Br in both phases. Thus, bromine and, by extension, chlorine are expected to be efficiently recycled from the slab towards the volcanic arc.
Americus Perez, Susumu Umino, Graciano P. Yumul Jr., and Osamu Ishizuka
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The occurrence of boninite in the northern Zambales ophiolite is reported. Boninite is a relatively rare high-magnesium andesite that is intimately associated with early arc volcanism and the initiation of subduction zones. Taken as a whole, the geological and geochemical characteristics of Zambales and Izu-Ogasawara–Mariana forearc volcanic sequences enables a refined geodynamic reconstruction of subduction initiation.
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Short summary
Magnesium isotope ratios of arc lavas have been proposed as a proxy for serpentinite subduction, but uncertainties remain regarding their utility. Here we show that bulk serpentinite Mg isotope ratios are identical to the mantle, whereas the serpentinite mineral brucite is enriched in heavy Mg isotopes. Thus, Mg isotope ratios may only be used as serpentinite subduction proxies if brucite is preferentially mobilized from the slab at pressures and temperatures within the arc magma source region.
Magnesium isotope ratios of arc lavas have been proposed as a proxy for serpentinite subduction,...