“…These noble gas characteristics likely require a deep mantle source that is distinct from the convecting upper mantle source for MORB (Kurz et al, l982;l985;Graham et al, l998;Harrison et al, l999;Hilton et al, l999;Breddam et al, 2000;Dixon et al, 2000;Moreira and Sarda, 2000;Moreira et al, 2001;Stuart et al, 2003;Graham, 2005;Ballentine et al, 2005;Macpherson et al, 2005). In addition, there is evidence in some Icelandic lavas, from both noble gases and lithophile elements, for varying contributions from the upper mantle MORB source as well as from several ancient crustal and/or mafic components within the mantle (Hemond et al, l993;Hanan and Schilling, l997;Fitton et al, l997;Taylor et al, l997;Stecher et al, l999;Hanan et al, 2000;Breddam et al, 2000;Chauvel and Hemond, 2000;Kempton et al, 2000;Thirlwall et al, 2004;Macpherson et al, 2005;Thirlwall et al, 2006;Kokfelt et al, 2006). These relationships are consistent with melting and mixing that accompanies the physical setting of the present-day Iceland plume beneath the spreading Mid-Atlantic Ridge system.…”