High 3He/4He ratios in picritic basalts from Baffin Island and the role of a mixed reservoir in mantle plumes

Stuart, Finlay M.; Lass-Evans, Solveigh; Fitton, J. Godfrey; Ellam, Robert M.

doi:10.1038/nature01711

Cited by 288 publications

(226 citation statements)

References 29 publications

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“…Values of 3 He/ 4 He for the high R A Icelandic mantle source range from the maximum 3 He/ 4 He measured in mantle-derived volcanic rocks from the Iceland plume at 60 Ma ( 3 He/ 4 He = 50 R A , Stuart et al, 2003), to a lower value of 37 R A , based on a measurement of a Neogene lava from Iceland (Hilton et al,l999). In order to minimize the amount of ancient recycled crust necessary to create a hybrid component having 25-33 R A , the lower value of 37 R A is used in the models presented in the following sections.…”

Section: He Constraintsmentioning

confidence: 95%

“…These arguments appear to eliminate models for volcanism in Iceland solely involving the upper mantle or lithosphere with no involvement of a deep, convectively isolated lower mantle source (Anderson, 2000;Foulger and Pearson, 2001;Anderson, 2004, Foulger et al, 2005;Meibom et al, 2005 could be explained by primordial He derived from the core (e.g. Porcelli and Halliday, 2001 (Graham et al, l998;Hilton et al, l999;Stuart et al, 2003). East Greenland picrites erupted from the Iceland plume at 58 Ma have 3 He/ 4 He of up to 20 R A , but likely have been lowered via crustal contamination (Marty et al,l998).…”

Section: He Isotope Evidence For a Compositionally Evolving Iceland Pmentioning

confidence: 99%

“…The Iceland plume system is ideal for this examination because of the well-established high 3 He/ 4 He and the near-solar Ne isotopic compositions in many Iceland lavas. 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).…”

Section: Introductionmentioning

confidence: 99%

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186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

Brandon

Graham

Waight³

et al. 2007

Geochimica et Cosmochimica Acta

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Picrites from the neovolcanic zones in Iceland display a range in 187 Os/ 188 Os from 0.1297 to 0.1381 (γ Os = 0.0 to 6.5) and uniform 186 Os/ 188 Os of 0.1198375±32 (2σ). The value for 186 Os/ 188 Os is within uncertainty of the present-day value for the primitive upper mantle of 0.1198398±16. These Os isotope systematics are best explained by ancient recycled crust or melt enrichment in the mantle source region. If so, then the coupled enrichments displayed in 186 Os/ 188 Os and 187 Os/ 188 Os from lavas of other plume systems must result from an independent process, the most viable candidate at present remains core-mantle interaction. While some plumes with high 3 He/ 4 He, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not.A positive correlation between 187 Os/ 188 Os and 3 He/ 4 He from 9.6 to 19 R A in Iceland picrites is best modeled as mixtures of 500 Ma or older ancient recycled crust mixed with primitive mantle, creating a hybrid source region that subsequently mixes with the convecting MORB mantle during ascent and melting. This multistage mechanism to explain these isotope systematics is consistent with ancient recycled crust juxtaposed with more primitive, relatively He-rich mantle, in convective isolation from the upper mantle, most likely in the lowermost mantle. This is inconsistent with models that propose random mixing between heterogeneities in the convecting upper mantle as a mechanism to explain the observed isotopic variation in oceanic lavas or models that produce a high 3 He/ 4 He signature in melt depleted and strongly

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Section: He Constraintsmentioning

confidence: 95%

Section: He Isotope Evidence For a Compositionally Evolving Iceland Pmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

Brandon

Graham

Waight³

et al. 2007

Geochimica et Cosmochimica Acta

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show abstract

“…This results from the distinct origins of 3 He (essentially primordial) and 4 He (produced by the radioactive decay of U and Th) and their contrasted proportions in the Earth's reservoirs. When referred to the atmospheric ratio (R a = 1.38 × 10 −6 ), typical 3 He/ 4 He ratios vary from b0.05 R a in the continental crust to 8 ± 1 R a on average in MORB-type upper mantle, and up to~40-50 R a in products of plume-related ocean islands, such as Hawaii and Iceland (Ballentine and Burnard, 2002;Graham, 2002;Stuart et al, 2003). Furthermore, helium closely follows carbon dioxide during magma degassing and the CO 2 / 3 He ratio of volcanic gases is one important complementary indicator of their origin (Sano and Marty, 1995;Allard et al, 1997;Marty and Tolstikhin, 1998).…”

Section: Introductionmentioning

confidence: 99%

Helium isotope systematics of volcanic gases and thermal waters of Guadeloupe Island, Lesser Antilles

Jean‐Baptiste

Allard

Fourré

et al. 2014

Journal of Volcanology and Geothermal Research

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The island of Guadeloupe is located in the middle of the 850 km long Lesser Antilles island arc. Present-day volcanic and geothermal activity is concentrated in two systems both located in the southwestern part of the island (Basse Terre): the La Soufrière volcanic complex and the Bouillante hydrothermal system, some 20 km to the northwest of the volcano. We report here the largest isotopic data set for helium isotopes in hydrothermal gases and waters from both systems, acquired between 1980 and 2012. 3 He/ 4 He ratios in the fumarolic gases of La Soufrière volcano have been quite homogeneous and stable over the last thirty years. The average ratio of 8.2 ± 0.2 R a confirms that the volcano is tapping a MORB-like mantle source. In contrast, the nearby Bouillante geothermal system displays a much lower 3 He/ 4 He ratio (4.5 ± 0.1 R a ). He-C elemental and isotopic relationships show that both systems are actually fed by the same magmatic source, and that their marked difference in 3 He/ 4 He results from the 4 He contamination of the Bouillante deep aquifer by the surrounding wallrock. This conclusion is strengthened by the spatial distribution of 3 He/ 4 He ratios which shows that La Soufrière fumaroles and the Bouillante geothermal system are the two end-members of a spatial trend of decreasing 3 He/ 4 He ratio with distance from La Soufrière summit dome, implying an increasing addition of radiogenic 4 He from the host rocks away from the present-day active volcanic edifice.

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“…An additional problem with the "ghost helium" model is that rutile may still be stable in a pure eclogite mantle component that is upwelling beneath a hotspot; the residual rutile will hold back TITAN in the source, and as a result, positive TITAN anomalies will not be observed in the erupted lavas. However, if the eclogite is melted to sufficiently high degrees beneath a hotspot, the rutile will be completely consumed and not present in the residue (Gaetani et al, 2007 (Stuart et al, 2003) may provide an important test case for this hypothesis.…”

Section: Mixing Asthenospheric Dmm Peridotite With Refractory Eclogitementioning

confidence: 99%

Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity

Jackson¹

2008

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AcknowledgementsFirst off, I want to thank my advisor, Stan Hart, for being so generous, with his time, his resources, and his thoughts. Stan sent me to the edges of the earth to collect rocks on islands and by sea ("a happy student is a traveling student"). And the fishing trips didn't end when I got back to the lab. When I went to him for answers, I often just ended up with more questions, we'd dream up a dozen projects, and he'd send me off with more projects and questions (back in my office, I'd realize that the meeting didn't go as I'd planned)! But the questions were more important than the answers: the questions will keep me employed after I graduate! It's only now that I'm realizing that without so much independence to explore (though frightening at times), I may have never understood that I was capable of generating some fun ideas! I can't express my gratitude to Nobu Shimizu and Mark Kurz for their "open door" policy. They are always ready to give me time, sit down, and hash out new ideas. Their offices are idea factories. I don't know how I would have written this thesis without their constant input.My deepest appreciation to J. Collins for sweating it out with me in the field in Samoa, and to the rest of my committee, P. Kelemen, Erik Hauri and Fred Frey for their stimulating input and for traveling so far to attend the general exam, thesis defense, and committee meetings.J. Blusztajn has always been so optimistic and helpful, and has given me so much of his time and advice. J. Curtice and T. Atwood have also given me dollops of help, and without them I could not have accomplished much of the thesis work.I am so thankful for the friendship of my dear friends, S. Hoffmann, D. Stuebe and J. Blythe, Heidi Marcella, Carolyn Walker, Lauge Sokol-Hessner and Hannah Cole. They kept me going when the times were rough, and we shared many of the best times as well.I am also thankful for the friendship and advice that I received from the "old guard" of JP students, who left the WHOI "nest" before me.

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High 3He/4He ratios in picritic basalts from Baffin Island and the role of a mixed reservoir in mantle plumes

Cited by 288 publications

References 29 publications

186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

Helium isotope systematics of volcanic gases and thermal waters of Guadeloupe Island, Lesser Antilles

Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity

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