The heterogeneous Iceland plume: new insights from the alkaline basalts of the Snaefell volcanic centre

V. L. Hards, P. D. Kempton and R. N. Thompson
Journal of the Geological Society, 152, 1003-1009, 1 November 1995, https://doi.org/10.1144/GSL.JGS.1995.152.01.21

Abstract

It has been accepted for some time that mixing between MORB-source mantle and the Iceland plume (geochemically relatively ‘reriched’ mantle) occurs along the Reykjanes Ridge. The composition of the basalts becomes progressively more enriched in lithophile elements towards Iceland. Within Iceland itself, there is significant variation in the composition of the mafic volcanic rocks. Although variations in degree of melting of a single source could have produced the elemental compositions of the Icelandic picritic, tholeiitic and alkalic basalts, their isotope systematics are not consistent with this model and require differences in source chemistry. Therefore, either MORB-source mantle has been mixed into the plume or the plume itself is heterogeneous. The clearest indications come from Pb isotopic data, which suggest that MORB-source mantle was excluded from the generation of Icelandic volcanic rocks.

Keywords

References

    1. Aitken B. G.,
    2. Echeverría L. M.
    (1984) Petrology and geochemistry of komatiites and tholeiites from Gorgona island, Colombia. Contributions to Mineralogy and Petrology 86:94–105.
    OpenUrlCrossRefWeb of Science
    1. Bott M. H. P.
    (1988) in Early Tertiary Volcanism and the opening of the NE Atlantic, A new look at the causes and consequences of the Iceland hot-spot, Geological Society London, Special Publications, eds Morton A. C., Parson L. M. 39, pp 15–23.
    OpenUrlAbstract/FREE Full Text
    1. Campbell I. H.,
    2. Griffiths R. W.
    (1992) The changing nature of mantle hotspots through time: implications for the chemical evolution of the mantle. Journal of Geology 92:497–523.
    OpenUrl
    1. Cohen R. S.,
    2. O’Nions R. K.
    (1982) The Pb, Nd and Sr isotopic structure of ocean ridge basalts. Journal of Petrology 23:299–324.
    OpenUrlCrossRefWeb of Science
    1. Condomines M.,
    2. Grönvold K.,
    3. Hooker P. J.,
    4. Muehlenbachs K.,
    5. O’Nions R. K.,
    6. Oskarsson N.,
    7. Oxburgh E. R.
    (1983) He, O, Sr and Nd isotopic relationships in Icelandic volcanics. Earth Science and Planetary Letters 66:125–136.
    OpenUrlCrossRef
    1. Courtney R. C.,
    2. White R. S.
    (1986) Anomalous heat flow and geoid across the Cape Verde rise: evidence for dynamic support from a thermal plume in the mantle. Geophysical Journal of the Royal Astrological Society 87:815–867.
    OpenUrl
    1. Desonie D. L.,
    2. Duncan R. A.,
    3. Natland J. H.
    (1993) Temporal and geochemical variability of volcanic products of the Marquesas Hotspot. Journal of Geophysical Research 98:17 649–17 665.
    OpenUrlCrossRefWeb of Science
    1. Dupré B.,
    2. Allègre C. J.
    (1980) Pb-Sr-Nd isotopic correlation and the chemistry of the North Atlantic Mantle. Nature 286:17–22.
    OpenUrlCrossRef
    1. Elliott T. R.
    (1991) Element fractionation in the petrogenesis of ocean island basalts. PhD Thesis (The Open University).
    1. Elliott T. R.,
    2. Hawkesworth C. J.,
    3. Grönvold K.
    (1991) Dynamic melting of the Iceland Plume. Nature 351:201–206.
    OpenUrlCrossRefWeb of Science
    1. Furman T.,
    2. Frey F. A.,
    3. Park K.-H.
    (1991) Chemical constraints on the petrogenesis of mildly alkaline lavas from Vestmannaeyjar, Iceland: the Eldfell (1973) and Surtsey (1963–1967) eruptions. Contributions to Mineralogy and Petrology 109:19–37.
    OpenUrlCrossRefWeb of Science
    1. Hart S. R.,
    2. Hauri E. H.,
    3. Oschmann L. A.,
    4. Whitehead J. A.
    (1992) Mantle plumes and entrainment: isotopic evidence. Science 256:517–520.
    OpenUrlAbstract/FREE Full Text
    1. Hauri E. H.,
    2. Whitehead J. A.,
    3. Hart S. R.
    (1994) Fluid dynamics and geochemical aspects of entrainment in mantle plumes. Journal of Geophysical Research 99:24 275–24 300.
    OpenUrlCrossRefWeb of Science
    1. Hémond C.,
    2. Arndt N. T.,
    3. Lichtenstein U.,
    4. Hofmann A. W.
    (1993) The heterogeneous Iceland Plume: Nd-Sr-O Isotopes and trace element constraints. Journal of Geophysical Research 98:15 833–15 850.
    OpenUrlCrossRef
    1. Ito E.,
    2. White W. M.,
    3. Göpel C.
    (1987) The O, Sr, Nd & Pb isotope geochemistry of MORB. Chemical Geology 62:157–176.
    OpenUrlCrossRefWeb of Science
    1. Jakobsson S. P.
    (1972) Chemistry and distribution pattern of recent basaltic rocks in Iceland. Lithos 5:365–385.
    OpenUrlCrossRef
    1. Kostopoulos D. K.,
    2. James S. D.
    (1992) Parameterization of the melting regime of the shallow upper mantle and the effects of variable lithospheric stretching on mantle modal stratification and trace element concentration in magmas. Journal of Petrology 33:665–691.
    OpenUrlCrossRefWeb of Science
    1. Langmuir C. H.,
    2. Vocke R. D.,
    3. Hanson G. N.,
    4. Hart S.
    (1978) A general mixing equation with application to Icelandic basalts. Earth Science and Planetary Letters 37:380–392.
    OpenUrlCrossRef
    1. Meyer P. S.,
    2. Sigurdsson H.,
    3. Schilling J.-G.
    (1985) Petrological and geochemical variations along Iceland’s volcanic zones. Journal of Geophysical Research 90:10 043–10 072.
    OpenUrlCrossRef
    1. Nicholson H.,
    2. Condomines M.,
    3. Fitton J. G.,
    4. Fallick A. E.,
    5. Grönvold K.,
    6. Rogers G.
    (1991) Geochemical and isotopic evidence for crustal assimilation beneath Krafla, Iceland. Journal of Petrology 32:1005–1020.
    OpenUrlCrossRefWeb of Science
    1. Oskarsson N.,
    2. Steinthorsson S.,
    3. Sigvaldason G. E.
    (1985) Iceland geochemical anomaly: volcanotectonics, chemical fractionation and evolution of the crust. Journal of Geophysical Research 90:10 011–10 025.
    OpenUrlCrossRef
    1. Ryan M. P.
    (1990) in Magma Transport and Storage, The physical nature of the Icelandic magma transport system, ed Ryan M.P. (John Wiley & Sons, Chichester), pp 175–220.
    1. Saemundsson K.
    (1979) Outline of the geology of Iceland. Jokull 29:7–28.
    OpenUrl
    1. Schilling J.-G.
    (1973) Iceland mantle plume: geochemical study of the Reykjanes Ridge. Nature 242:565–571.
    OpenUrlCrossRef
    1. Schilling J. G.,
    2. Zajac M.,
    3. Evans R.,
    4. Johnson T.,
    5. White W.,
    6. Devine J. D.,
    7. Kingsley R.
    (1983) Petrologic and geochemical variations along the Mid-Atlantic Ridge from 29°N to 73°N. American Journal of Science 283:510–586.
    OpenUrlAbstract/FREE Full Text
    1. Shaw D. M.
    (1970) Trace element fractionation during anatexis. Journal of Petrology 34:237–243.
    OpenUrl
    1. Slater L.,
    2. Grönvold K.,
    3. Shimizu N.,
    4. McKenzie D.
    (1994) Melting beneath the Theistareykir region, NE Iceland. Mineralogical Magazine 58A:848–849.
    OpenUrl
    1. Sleep N. H.
    (1994) Lithospheric thinning by midplate mantle plumes and the thermal history of hot plume material ponded at sublithospheric depths. Journal of Geophysical Research 99:9 327–9 343.
    OpenUrlCrossRef
    1. Sobolev A. V.,
    2. Gurenko A. A.,
    3. Shimizu N.
    (1994) Ultra-depleted melts from Iceland: data from melt inclusion studies. Mineralogical Magazine 58A:860–861.
    OpenUrl
    1. Steinthorsson S.,
    2. Oskarsson N.,
    3. Sigvaldason G. E.
    (1985) Origin of alkali basalts in Iceland: a plate tectonic model. Journal of Geophysical Research 90:10 027–10 042.
    OpenUrlCrossRef
    1. Sun S.-s.,
    2. Jahn B.-M.
    (1975) Pb and Sr isotopes in post-glacial basalts from Iceland. Nature 255:527–530.
    OpenUrlCrossRef
    1. Sun S.-s.,
    2. McDonough W. F.
    (1989) in Magmatism in the Ocean Basins, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes, Geological Society, London, Special Publications, eds Saunders A. D., Norry M. J. 42, pp 313–345.
    OpenUrlAbstract/FREE Full Text
    1. Sun S.-s.,
    2. Tatsumoto M.,
    3. Schilling J.-G.
    (1975) Mantle plume mixing along the Reykjanes Ridge. Science 190:143–147.
    OpenUrlWeb of Science
    1. Thompson R. N.,
    2. Gibson S. A.
    (1991) Subcontinental mantle plumes, hot spots and pre-existing thinspots. Journal of the Geological Society, London 148:973–977.
    OpenUrlCrossRefWeb of Science
    1. Tryggvasson K.,
    2. Husebye E. S.,
    3. Stefansson R.
    (1983) Seismic image of the Iceland hotspot. Tectonophysics 100:97–118.
    OpenUrlCrossRefWeb of Science
    1. Watson S.,
    2. McKenzie D.
    (1991) Melt generation by plumes: a study of Hawaiian volcanism. Journal of Petrology 32:501–537.
    OpenUrlCrossRefWeb of Science
    1. Weaver B. L.
    (1991) The origin of ocean island basalt end-member compositions: trace element and isotopic constraints. Earth Science and Planetary Letters 104:381–397.
    OpenUrlCrossRef
    1. White R. S.,
    2. McKenzie D.
    (1989) Magmatism at rift zones: the generation of volcanic continental margins and flood basalts. Journal of Geophysical Research 94:7 685–7 729.
    OpenUrlCrossRefWeb of Science
    1. White R. S.,
    2. McKenzie D.
    Mantle plumes and flood basalts. Journal of Geophysical Research, in press.
    1. White W. M.,
    2. McBirney A. R.,
    3. Duncan R. A.
    (1993) Petrology and geochemistry of the Galapagos islands: portrait of a pathological mantle plume. Journal of Geophysical Research 98:19 533–19 563.
    OpenUrlCrossRef
    1. Zindler A.,
    2. Hart S.
    (1986) Chemical geodynamics. Annual Review of Earth and Planetary Sciences 14:493–571.
    OpenUrlCrossRefWeb of Science
    1. Zindler A.,
    2. Frey F. A.,
    3. Jakobsson S. P.
    (1979) Nd and Sr Isotope ratios and rare earth element abundances in Reykjanes peninsula basalts: evidence for mantle heterogeneity beneath Iceland. Earth Science and Planetary Letters 45:249–262.
    OpenUrlCrossRef
    1. Zindler A.,
    2. Staudigel H.,
    3. Batiza R.
    (1984) Isotope and trace element geochemistry of young Pacific seamounts: implications for the scale of upper mantle heterogeneity. Earth and Planetary Science Letters 70:175–195.
    OpenUrlCrossRefWeb of Science
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