Source components of the Gran Canaria Canary Isla

Authors: Andrey A Gurenko Kaj A Hoernle Alexander V Sobolev Folkmar Hauff HansUlrich Schmincke

Publish Date: 2009/10/13

Volume: 159, Issue: 5, Pages: 689-702

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Abstract

The Canary Island primitive basaltic magmas are thought to be derived from an HIMUtype upwelling mantle containing isotopically depleted NMORBtype component having interacted with an enriched EMtype component the origin of which is still a subject of debate We studied the relationships between Ni Mn and Ca concentrations in olivine phenocrysts 856–900 mol Fo 1722–3915 ppm Ni 1085–1552 ppm Mn 1222–3002 ppm Ca from the most primitive subaerial and ODP Leg 157 highsilica picritic to olivine basaltic lavas with their bulk rock Sr–Nd–Pb isotope compositions 87Sr/86Sr = 070315–070331 143Nd/144Nd = 051288–051292 206Pb/204Pb = 1955–1993 207Pb/204Pb = 1560–1563 208Pb/204Pb = 3931–3969 Our data point toward the presence of both a peridotitic and a pyroxenitic component in the magma source Using the model Sobolev et al in Science 316412–417 2007 in which the reaction of Sirich melts originated during partial melting of eclogite a high pressure product of subducted oceanic crust with ambient peridotitic mantle forms olivinefree reaction pyroxenite we obtain an end member composition for peridotite with 87Sr/86Sr = 070337 143Nd/144Nd = 051291 206Pb/204Pb = 1936 207Pb/204Pb = 1561 and 208Pb/204Pb = 3907 EMtype end member and pyroxenite with 87Sr/86Sr = 070309 143Nd/144Nd = 051289 206Pb/204Pb = 2003 207Pb/204Pb = 1562 and 208Pb/204Pb = 3984 HIMUtype end member Mixing of melts from these end members in proportions ranging from 70 peridotite and 30 pyroxenite to 28 peridotite and 72 pyroxenite derived melt fractions can generate the compositions of the most primitive Gran Canaria shield stage lavas Combining our results with those from the lowsilica rocks from the western Canary Islands Gurenko et al EPSL 277514–524 2009 at least four distinct components are required We propose that they are 1 HIMUtype pyroxenitic component representing recycled ocean crust of intermediate age from the plume center 2 HIMUtype peridotitic component ancient recycled ocean crust stirred into the ambient mantle from the plume margin 3 depleted MORBtype pyroxenitic component young recycled oceanic crust in the upper mantle entrained by the plume and 4 EMtype peridotitic component from the asthenosphere or lithosphere above the plume centerWe thank S Hauff for assistance in carrying out Sr–Nd–Pb isotope analyses and the Ocean Drilling Program for providing HUS and AAG with the samples drilled during the ODP Leg 157 The Museum of Natural History Washington DC kindly provided us with standards for electron microprobe analysis Thorough reviews by Andreas Klügel Christian Tegner and one anonymous referee helped us to improve the manuscript substantially and are gratefully acknowledged This work was supported by the Wolfgang Paul Award of the Alexander von Humboldt Foundation to AVS the Max Planck Society DFG grants SCHM 250/64 821 and HA3097/2 to HUS KH and FH the Russian Basic Research Foundation grant 060565234 to AVS and the Russian Academy of Sciences Editorial handling of the manuscript by Jochen Hoefs is very much appreciated

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