Enriched,HIMU-type peridotite and depleted recycled pyroxenite in the Canary plume: A mixed-up mantle |
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| Authors: | Andrey A Gurenko Alexander V Sobolev Kaj A Hoernle Folkmar Hauff Hans-Ulrich Schmincke |
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| Institution: | 1. Max-Planck-Institut für Chemie, Abteilung Geochemie, Postfach 3060, D-55020 Mainz, Germany;2. Woods Hole Oceanographic Institution, Geology and Geophysics, Woods Hole, MA 02543, USA;3. Vernadsky Institute of Geochemistry and Analytical Chemistry, Kosigin Str. 19, 119991 Moscow, Russia;4. IfM-GEOMAR Leibniz Institute for Marine Sciences, Dynamics of the Ocean Floor, Wischhofstraße 1-3, D-24148 Kiel, Germany;1. Department of Geosciences and Natural Resource Management (Geology Section), Copenhagen University, Øster Voldgade 10, 1350 Copenhagen K, Denmark;2. Department of Geology, University of Otago, Leith Street, Dunedin 9054, New Zealand;3. Institut für geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany;1. V.S. Sobolev Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090, Russia;2. Novosibirsk State University, Novosibirsk 630090, Russia;3. Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan;1. Department of Geology and Geophysics, School of Ocean and Earth Science and Technology, University of Hawaii, Manoa, Honolulu, HI 96822, USA;2. Department of Geological Sciences, San Diego State University, San Diego, CA 92182, USA;3. United States Geological Survey, Denver Federal Center, Denver, CO 80225, USA;4. Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA;5. Schlumberger-Doll Research, Reservoir Geosciences, Cambridge, MA 02139, USA;6. Department of Earth Science, University of California Santa Barbara, Santa Barbara, CA 93106, USA;1. Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8066, USA;2. Boston University, Department of Earth and Environment, Boston, MA 02215, USA;3. UC Santa Barbara, Department of Earth Science, Santa Barbara, CA 93106, USA;4. Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA;5. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA;1. Research School of Earth Sciences, Australian National University, Canberra, Australia;2. Faculty of Earth and Life Sciences, VU University Amsterdam, Amsterdam, The Netherlands;3. School of Earth Sciences, University of Melbourne, Melbourne, Australia;4. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC, USA;5. Centre for Sustainable Energy Systems, Australian National University, Canberra, Australia;6. Department for Geosciences, University of Tübingen, Tübingen, Germany |
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| Abstract: | The Earth's mantle is chemically and isotopically heterogeneous, and a component of recycled oceanic crust is generally suspected in the convecting mantle Hofmann and White, 1982. Mantle plumes from ancient oceanic crust. Earth Planet. Sci. Lett. 57, 421–436]. Indeed, the HIMU component (high µ = 238U/204Pb), one of four isotopically distinct end-members in the Earth's mantle, is generally attributed to relatively old (≥ 1–2 Ga) recycled oceanic crust in the form of eclogite/pyroxenite, e.g. Zindler and Hart, 1986. Chemical geodynamics. Ann. Rev. Earth Planet. Sci. 14, 493–571]. Although the presence of the recycled component is generally supported by element and isotopic data, little is known about its physical state at mantle depths. Here we show that the concentrations of Ni, Mn and Ca in olivine from the Canarian shield stage lavas, which can be used to assess the physical nature of the source material (peridotite versus olivine-free pyroxenite) Sobolev et al., 2007. The amount of recycled crust in sources of mantle-derived melts. Science 316, 412–417], correlate strongly with bulk rock Sr, Nd and Pb isotopic ratios. The most important result following from our data is that the enriched, HIMU-type (having higher 206Pb/204Pb than generally found in the other mantle end-members) signature of the Canarian hotspot magmas was not caused by a pyroxenite/eclogite constituent of the plume but appears to have been primarily hosted by peridotite. This implies that the old (older than ~ 1 Ga) ocean crust, which has more evolved radiogenic isotope compositions, was stirred into/reacted with the mantle so that there is not significant eclogite left, whereas younger recycled oceanic crust with depleted MORB isotopic signature (< 1 Ga) can be preserved as eclogite, which when melted can generate reaction pyroxenite. |
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