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... samples from Mt. Erebus, Antarctica. The Samoan Islands represent the end-member “EM2” enriched mantle component and are characterized by radio-Fig. 1. (230Th/232Th) versus (238U/232Th) for the our global compilation of lit mass spectrometric methods [5,10,11,15–27], Iceland [28,29], Canaries [30– samples of uncertain eruption age, or which have been identified in the publi the newMt. Erebus samples are historic, and the new Samoan samples are dem 230Th–226Ra–210Pb and 210Po disequilibria (Sims et al., in preparation).genic 87Sr/86Sr, unradiogenic 143Nd/144Nd, and low to moderate 206Pb/204Pb [14]. The Mt. Erebus samples are “HIMU” having intermediate 87Sr/86Sr, intermediate 143Nd/144Nd, and radiogenic 206Pb/ 204Pb. While Mt. Erebus does not represent the end-member mantle component HIMU, there are no samples young enough for U–Th disequilibria studies from Mangai-Tubai (the HIMU end-member). These new data are then compared with the MORB and OIB database for which U–Th disequilibria and longer-lived radiogenic isotopes of Sr, Nd, and Pb have been measured by mass spectrometric methods. 2. Comparison of (230Th/232Th) and (238U/232Th) with Sr, Nd and Pb isotopes in the global oceanic da...

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...source region (geochemistry) LIP geochemistry can be used to characterize mantle sources, provided it is not overprinted by lithosphere or crustal contamination, a common problem with continental LIPs (Arndt and Christensen, 1992). The involvement of known mantle reservoirs, depleted MORB mantle (DMM), enriched mantle I (EMI), enriched mantle II (EMII), mantle with a high time-integrated U–Pb ratio (HIMU) and focus zone (FOZO), can be assessed using isotopes and trace elements (e.g., Hart et al., 1992; BlichertToft and White, 2001; Condie, 2001; van Keken et al., 2002; Ernst and Buchan, 2003; Workman et al., 2004). DMM represents an upper mantle reservoir, the source for mid-ocean ridge basalts. EMI, EMII and HIMU are enriched components that may represent recycled oceanic lithosphere F a small contribution from the continental crust. FOZO is a depletedreservoir that also has elevated He and Os anomalies. There is debate as to whether it represents an ancient and deep depleted source (e.g., van Keken et al., 2002; Workman et al., 2004) or is linked to shallow mantle processes (e.g., Meibom et al., 2003). The role of recycled crustal material is increasingly being recognized as an important component in...

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...ositions (>0.721 [Jackson et al., 2007a]). Two other Samoan lavas (Ta’u island sample T54 and clinopyroxene separates fromMalulalu seamount sample AVON378-1) with less extreme 87Sr/86Sr compositions [=-=Workman et al., 2004-=-; Jackson et al., 2009] were also selected for 142Nd/144Nd measurement. The Hawaiian Koolau (KOO-8 and KOO-30) and Loihi (KK-18-18) samples were selected because they represent two extreme composition...

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...hauvel et al., 1992). Alternatively, the enriched components could be metasomatized oceanic or continental lithospheric mantle (Sun & McDonough, 1989; Halliday et al., 1992, 1995; Niu & O’Hara, 2003; =-=Workman et al., 2004-=-; Pilet et al., 2005, 2008; Panter et al., 2006). Although these alternative hypotheses of crustal recycling vs metasomatized lithosphere are frequently considered to be mutually exclusive (Hofmann, 1...

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...per continental crust (Hegner & Pallister, 1989; Jarrar et al., 2003), Depleted MORB Mantle (DMM) (Workman & Hart, 2005), Enriched Mantle I (EMI) (Lustrino & Dallai, 2003), Enriched Mantle II (EMII) (=-=Workman et al., 2004-=-), Low Velocity Component (LVC) (Hoernle et al., 1995) and Prevalent Mantle (PREMA) (Wo« rner et al.,1986). In (a), the Bulk Silicate Earth estimate (BSE) and Chondritic Uniform Reservoir (CHUR) are f...

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...ntinuously supplied to thesupper mantle [Albarède and van der Hilst 2002]. Other important contributors includessub-continental lithosphere, metasomatic reactions and continental crust [Hofmann 1997;s=-=Workman et al. 2004-=-]. Subducted and recycled components are dispersed in the uppersmantle by convection and juxtaposed with depleted residues. The result is a highlysheterogeneous assemblage of small-to-moderate scale (...

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...gnificantly affected by redefinition of the compositions of Hart et al. (1992) end-members; for example, adopting isotope ratios as suggested in the recent literature for DMM, EMI, EMII and HIMU (e.g.=-=Workman et al., 2004-=-; Stracke et al., 2005). As the tetrahedron is simply a tool with which to ‘visualize’ the R3 space for the projection of points from Rn, it may be dropped, with the focus being moved to the point dis...

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...). As an alternative to recycled crust or lithosphere which are always needed for the plume model, metasomatic veins in lithospheric mantle can be the main source of the enrichment (Niu et al., 2002; =-=Workman et al., 2004-=-; Donnelly et al., 2004; Pilet et al., 2005). If so, the enriched mantle components found in the AOC are hornblendite veins which were formed by infiltration of low-degree melts of the Low Velocity Zo...

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...iscontinuity [3]. All other reservoirs have traditionally been placed in the lower mantle and major efforts have been directed towards understanding the processes that formed each different reservoir =-=[1,2,4,5]-=-. Radiogenic isotopes have played a very important role in this development and have provided information regarding the time-integrated geochemical evolution of each hypothetical reservoir. This has a...