Multiple pulses of the mantle plume: Evidence from tertiary icelandic lavas

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Abstract

We present major and trace element concentrations and Sr-Nd-Hf-Pb isotope data for the c. 13-2 Ma Tertiary lavas from eastern Iceland. Our new geochemical results, together with published geological, geochronological, geochemical and geophysical data, are used to evaluate temporal changes in mantle sources contributing to the Tertiary Icelandic magmatism and the relative roles of these sources in magma productivity. The trace element and radiogenic isotopic compositions clearly distinguish three distinct end-member components in the Tertiary magmatism. Temporal variations in lava geochemistry can be attributed to changes in the relative contributions of these three end-member components to the erupted magmas and correlated with temporal variations in magma productivity. The extrusion of lavas with geochemically and isotopically enriched compositions was particularly pronounced at ∼13-12 and 8-7 Ma, coincident in time with higher magma productivity. However, the geochemical characteristics of the lavas are different during these two periods: the 13-12 Ma lavas have more radiogenic 176Hf/177Hf and less radiogenic 206Pb/204Pb than those erupted from 8 to 7 Ma. The eruption of relatively depleted lavas, at around 10 Ma and younger than 6-5 Ma, is coincident with lower magma productivity. The correlation between the composition and productivity of the Tertiary lavas from eastern Iceland is probably due to periodic changes in the involvement of the enriched end-member component, followed by a gradation to periods dominated by the signature of the depleted end-member component and lower magma productivity, at an approximate frequency of 5 Myr.

Original languageEnglish
Pages (from-to)1365-1396
Number of pages32
JournalJournal of Petrology
Volume49
Issue number7
DOIs
Publication statusPublished - Jul 1 2008

Keywords

  • Magma productivity
  • Mantle plume
  • Mantle source
  • Temporal variation
  • Trace element and isotope geochemistry

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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