1. Testing the Recycled Gabbro Hypothesis for the Origin of 'Ghost Plagioclase' Melt Signatures Using 87Sr/ 86 Sr of Individual Olivine‐Hosted Melt Inclusions from Hawai'i
- Author
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Benjamin L. Byerly, Allison A. Price, A.A. Reinhard, J. P. Marske, Estelle Rose-Koga, Matthew G. Jackson, M. E. Peterson, O. E. Anderson, Isotope Geochemistry Facility – Center for Mantle Zoology, University of California Santa Barbara, Department of Earth Science, Santa Barbara, CA, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Department of Terrestrial Magnetism [Carnegie Institution], Carnegie Institution for Science [Washington], AAAS Science and Technology Policy, ORISE Fellow hosted by the DOE, Washington, DC, Los Alamos National Laboratory, Nuclear and Radiochemistry Group, Los Alamos, NM, ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), and Carnegie Institution for Science
- Subjects
010504 meteorology & atmospheric sciences ,Geochemistry ,trace elements ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Mantle (geology) ,Hawaii ,Geochemistry and Petrology ,Oceanic crust ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Plagioclase ,ghost plagioclase ,TIMS ,0105 earth and related environmental sciences ,Melt inclusions ,geography ,geography.geographical_feature_category ,Olivine ,Gabbro ,melt inclusion ,Geophysics ,Volcano ,13. Climate action ,engineering ,Inclusion (mineral) ,Geology - Abstract
co-auteur étranger; International audience; Melt inclusions with large, positive Sr anomalies have been described in multiple tectonic settings, and the origins of this unusual geochemical feature are debated. Three origins have been proposed involving plagioclase as the source of the elevated Sr: (i) direct assimilation of plagioclase-rich lithologies, (ii) recycled lower oceanic gabbro in the mantle source, and (iii) shallow-level diffusive interaction between present day lower oceanic crust (i.e., plagioclase-bearing lithologies) and the percolating melt. A “ghost plagioclase” signature (i.e., a large, positive Sr anomaly without associated high Al2O3) is present in melt inclusions from Mauna Loa. We present new 87Sr/86Sr measurements of individual olivine-hosted melt inclusions from three Hawaiian volcanoes, Mauna Loa, Loihi, and Koolau. The dataset includes a Mauna Loa melt inclusion with the highest reported Sr anomaly (or highest (Sr/Ce)N, which is 7.2) for Hawai'i. All melt inclusions have 87Sr/86Sr values within the range reported previously for the lavas from each volcano. Critically, the 87Sr/86Sr of the high (Sr/Ce)N melt inclusion lies within the narrow range of Mauna Loa melts that lack high (Sr/Ce)N signatures. To explain the high (Sr/Ce)N ratio of the ghost plagioclase signature using an ancient recycled gabbro would therefore require the gabbro-infused mantle source to evolve, by chance, to have the same 87Sr/86Sr as the source of the Mauna Loa melts that lack a recycled gabbro (ghost plagioclase) signature. Alternatively, shallow-level diffusive interactions between Mauna Loa plagioclase-rich cumulates and a percolating mantle-derived melt provides a simpler explanation for the presence of the high (Sr/Ce)N Mauna Loa melts.
- Published
- 2021
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