Source components of the Gran Canaria (Canary Islands) shield stage magmas: evidence from olivine composition and Sr–Nd–Pb isotopes

• Published in: Contributions to mineralogy and petrology Vol. 159; no. 5; pp. 689 - 702
• Main Authors: Gurenko, Andrey A., Hoernle, Kaj A., Sobolev, Alexander V., Hauff, Folkmar, Schmincke, Hans-Ulrich
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.05.2010; Springer Nature B.V; Springer Verlag
• Subjects: Earth and Environmental Science; Earth Sciences; Geochemistry; Geology; High pressure; Islands; Isotopes; Lithosphere; Magma; Marine; Mineral Resources; Mineralogy; Oceanic crust; Original Paper; Petrography; Petrology; Rocks; Sciences of the Universe; Silica; Upper mantle; Upwelling; Canary Islands; Spain; ASE, Atlantic, Canary Is; Germany, Berlin; ASE, Atlantic, Canary Is., Gran Canaria; Gran Canaria; Olivine; Canary Islands; Pyroxenite; Peridotite; Radiogenic isotopes; ODP Leg 157; Mantle plume; Ocean crust; Recycling
• ISSN: 0010-7999; 1432-0967
• DOI: 10.1007/s00410-009-0448-8

The Canary Island primitive basaltic magmas are thought to be derived from an HIMU-type upwelling mantle containing isotopically depleted (NMORB)-type component having interacted with an enriched (EM)-type component, the origin of which is still a subject of debate. We studied the relationships between Ni, Mn and Ca concentrations in olivine phenocrysts (85.6–90.0 mol.% Fo, 1,722–3,915 ppm Ni, 1,085–1,552 ppm Mn, 1,222–3,002 ppm Ca) from the most primitive subaerial and ODP Leg 157 high-silica (picritic to olivine basaltic) lavas with their bulk rock Sr–Nd–Pb isotope compositions ( 87 Sr/ 86 Sr = 0.70315–0.70331, 143 Nd/ 144 Nd = 0.51288–0.51292, 206 Pb/ 204 Pb = 19.55–19.93, 207 Pb/ 204 Pb = 15.60–15.63, 208 Pb/ 204 Pb = 39.31–39.69). 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 316:412–417, 2007) in which the reaction of Si-rich melts originated during partial melting of eclogite (a high pressure product of subducted oceanic crust) with ambient peridotitic mantle forms olivine-free reaction pyroxenite, we obtain an end member composition for peridotite with 87 Sr/ 86 Sr = 0.70337, 143 Nd/ 144 Nd = 0.51291, 206 Pb/ 204 Pb = 19.36, 207 Pb/ 204 Pb = 15.61 and 208 Pb/ 204 Pb = 39.07 (EM-type end member), and pyroxenite with 87 Sr/ 86 Sr = 0.70309, 143 Nd/ 144 Nd = 0.51289, 206 Pb/ 204 Pb = 20.03, 207 Pb/ 204 Pb = 15.62 and 208 Pb/ 204 Pb = 39.84 (HIMU-type 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 low-silica rocks from the western Canary Islands (Gurenko et al. EPSL 277:514–524, 2009), at least four distinct components are required. We propose that they are (1) HIMU-type pyroxenitic component (representing recycled ocean crust of intermediate age) from the plume center, (2) HIMU-type peridotitic component (ancient recycled ocean crust stirred into the ambient mantle) from the plume margin, (3) depleted, MORB-type pyroxenitic component (young recycled oceanic crust) in the upper mantle entrained by the plume, and (4) EM-type peridotitic component from the asthenosphere or lithosphere above the plume center.