Extreme HIMU in an oceanic setting: the geochemistry of Mangaia Island (Polynesia), and temporal evolution of the Cook—Austral hotspot

Woodhead, Jon

doi:10.1016/0377-0273(96)00002-9

Cited by 167 publications

(109 citation statements)

References 46 publications

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“…As mentioned in Section "Samples", the analyzed Mangaia, Tubuai, and Rurutu OIBs are classified as HIMU OIBs ( 206 Pb/ 204 Pb > 20.5) (Figs. 3a and 3b) (Kogiso et al, 1997 Palacz and Saunders, 1986;Nakamura and Tatsumoto, 1988;Hauri and Hart, 1993;Woodhead, 1996;Chauvel et al, 1997;Hanyu and Nakamura, 2000;Schiano et al, 2001).…”

Section: Resultsmentioning

confidence: 99%

Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin

et al. 2005

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To investigate the origin of the HIMU (high-µ) reservoir in the mantle, we measured Li, Sr, and Nd isotopic compositions of several oceanic island basalts (OIBs) from the Polynesian region. We used a recently developed multiple-collector inductively coupled plasma mass spectrometry method that allows precise and accurate Li isotopic determinations. This study presents the first Li isotopic data on HIMU OIBs. Li] L-SVEC standard -1] × 1000) of the Polynesian HIMU OIBs (Mangaia, Tubuai, and Rurutu) range from +5.0‰ to +7.4‰, which are higher than those of fresh normal mid-ocean ridge basalt (N-MORB) glasses (ca. +3‰). The simultaneously measured K/Rb, Ba/Rb, and 87 Sr/ 86 Sr ratios indicate that the analyzed HIMU OIBs are free from significant posteruption alteration. These results suggest that the δ 7 Li value of the Polynesian HIMU source is never lower than those of the N-MORBs.Among the numerous models for the origin of the HIMU source, the most widely accepted model is that it involves subducted (dehydrated) oceanic crust. For this HIMU-origin model, our new Li isotopic results exclude the highly altered portion, that is, the uppermost part of the oceanic crust, because the δ 7 Li value of subducted highly altered MORB should be extremely low (δ 7 Li < fresh MORB). For these reasons, we propose that the Polynesian HIMU source is the relatively less-altered oceanic crust underlying the highly altered crust. Whereas Pb, Sr, and Nd isotopic signatures dominantly indicate the involvement of sediments in a source, the Li isotopic signature is more sensitive to the degree of alteration experienced by the basaltic crust and thus can be used to distinguish what part of the crust was trapped in the OIB magma. It therefore provides information complementary to that provided by the radiogenic isotopes.

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Section: Resultsmentioning

confidence: 99%

Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin

et al. 2005

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“…secondary isochron). Workman et al 2004;Eisele et al 2002;Woodhead 1996;Hauri and Hart 1997;Hofmann 1988;Su and Langmuir 2003;and Hauri, Hart and Farley unpublished). The dotted line represents the Nd/Pb ratio of Bulk Silicate Earth (BSE; McDonough and Sun 1995).…”

Section: Figure Captionsmentioning

confidence: 96%

“…standard errors): EM1 -10.2 ± 0.3; HIMU -15.9 ± 1.0; EM2 -11.9 ± 0.7; NMORB = 22.9. (Woodhead 1996;Hauri and Hart 1997). EM1 -average of 18 samples of Tedside Series, Pitcairn Island; average 206/204 Pb = 17.75 (Eisele et al 2002 and Hauri, Hart and Farley, unpublished).…”

Section: Figure Captionsmentioning

confidence: 99%

Mantle Pb paradoxes: the sulfide solution

Hart

Gaetani

2006

Contrib Mineral Petrol

116

108

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There is growing evidence that the budget of Pb in mantle peridotites is largely contained in sulfide, and that Pb partitions strongly into sulfide relative to silicate melt. In addition, there is evidence to suggest that diffusion rates of Pb in sulfide (solid or melt) are very fast. Given the possibility that sulfide melt 'wets' sub-solidus mantle silicates, and has very low viscosity, the implications for Pb behavior during mantle melting are profound. There is only sparse experimental data relating to Pb partitioning between sulfide and silicate, and no data on Pb diffusion rates in sulfides. A full understanding of Pb behavior in sulfide may hold the key to several long-standing and important Pb paradoxes and enigmas. The classical Pb isotope paradox arises from the fact that all known mantle reservoirs lie to the right of the Geochron, with no consensus as to the identity of the "balancing" reservoir. We propose that long-term segregation of sulfide (containing Pb) to the core may resolve this paradox.Another Pb paradox arises from the fact that the Ce/Pb ratio of both OIB and MORB is greater than bulk earth, and constant at a value of 25. The constancy of this "canonical ratio" implies similar partition coefficients for Ce and Pb during magmatic processes (Hofmann et al. 1986), whereas most experimental studies show that Pb is more incompatible in silicates than Ce. Retention of Pb in residual mantle sulfide during melting has the potential to bring the bulk partitioning of Ce into equality with Pb if the sulfide melt/silicate melt partition coefficient for Pb has a value of ~ 14. Modeling shows that the Ce/Pb (or Nd/Pb) of such melts will still accurately reflect that of the source, thus enforcing the paradox that OIB and MORB mantles have markedly higher Ce/Pb (and Nd/Pb) than the bulk silicate earth. This implies large deficiencies of Pb in the mantle sources for these basalts. Sulfide may play other important roles during magmagenesis: 1). advective/diffusive sulfide networks may form potent metasomatic agents (in both introducing and obliterating Pb isotopic heterogeneities in the mantle); 2). silicate melt networks may easily exchange Pb with ambient mantle sulfides (by diffusion or assimilation), thus 'sampling' Pb in isotopically heterogeneous mantle domains differently from the silicate-controlled isotope tracer systems (Sr, Nd, Hf), with an apparent 'de-coupling' of these systems.

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“…In the Cook-Austral Islands, lavas with HIMU signature only occur before 6 Ma on Mangaia, Tubuai, Rurutu, and Raivavae (Nakamura and Tatsumoto, 1988;Chauvel et al, 1992;Hémond et al, 1994;Woodhead, 1996;Kogiso et al, 1997a;Schiano et al, 2001;Lassiter et al, 2003;Hanyu et al, 2011a). Temporal isotopic variation within individual volcanoes has not been identified in these islands.…”

Section: Geochemical Heterogeneity In the South Pacificmentioning

confidence: 99%

“…Alternative models for the origin of HIMU reservoir consider chemical modification of the oceanic crust by hydrothermal alteration and subsequent dehydration during subduction (Hofmann and White, 1982;Weaver, 1991;Chauvel et al, 1992;Woodhead, 1996;Kogiso et al, 1997a;Tatsumi and Kogiso, 2003;Stracke et al, 2005;Hanyu et al, 2011a;Kawabata et al, 2011). Highpressure experiments have demonstrated that K, Pb, Rb, and Ba are highly fluid-mobile elements, in contrast to moderately mobile LREE and Sr and less-mobile Nb, U, and Th (Keppler, 1996;Kogiso et al, 1997b).…”

Section: Origin Of the Himu Reservoirmentioning

confidence: 99%

Origin of hotspots in the South Pacific: Recent advances in seismological and geochemical models

Suetsugu

Hanyu

2013

Geochem. J.

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Extreme HIMU in an oceanic setting: the geochemistry of Mangaia Island (Polynesia), and temporal evolution of the Cook—Austral hotspot

Cited by 167 publications

References 46 publications

Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin

Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin

Mantle Pb paradoxes: the sulfide solution

Origin of hotspots in the South Pacific: Recent advances in seismological and geochemical models

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