Solar neon in the Icelandic mantle: new evidence for an undegassed lower mantle

Moreira, Manuel; Breddam, Kresten; Curtice, Joshua; Kurz, Mark D.

doi:10.1016/s0012-821x(00)00351-4

Cited by 116 publications

(81 citation statements)

References 37 publications

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“…A similar inference was made based on the negative correlation of low δ 18 O with high 3 He/ 4 He observed in lavas from the neovocalanic zones in Iceland and the Reykjanes ridge (Thirlwall et al, 2006). Further support that the geochemical variability of Iceland magmatism reflects an origin from a deep mantle plume may be inferred from the primordial Ne isotopic compositions in neovolcanic zone lavas (Dixon et al, 2000;Moreira et al, 2001). Finally, the source of the high 3 He/ 4 He in the hybrid component cannot be the result of a largely outgassed (i.e.…”

Section: He Isotope Evidence For a Compositionally Evolving Iceland Psupporting

confidence: 58%

“…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 Isotope Evidence For a Compositionally Evolving Iceland Psupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

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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“…This approach gives a 3 He/ 22 Ne value of 8.5, which is lower than the MORB value of 11 but significantly greater than the value of 4 calculated for magmatism on the Reykjanes peninsula in SW Iceland (Dixon et al, 2000;Moreira et al, 2001). Therefore, Kolbeinsey Ridge represents the transition in light noble gas elemental ratios between those of the Mid-Atlantic Ridge remote from…”

Section: Parental Noble Gas Isotope Ratiosmentioning

confidence: 76%

“…It is possible to assess the fractionation of He from Ne by calculating the 3 He/ 22 Ne ratio of uncontaminated melts, as described by Moreira et al (2001) is 5000. This approach gives a 3 He/ 22 Ne value of 8.5, which is lower than the MORB value of 11 but significantly greater than the value of 4 calculated for magmatism on the Reykjanes peninsula in SW Iceland (Dixon et al, 2000;Moreira et al, 2001).…”

Section: Parental Noble Gas Isotope Ratiosmentioning

confidence: 99%

“…Prior work on Iceland has established that magmatic He and Ne (Mamyrin et al, 1972;Condomines et al, 1983;Kurz et al, 1985;Sano et al, 1985;Hilton et al, 1990;Burnard et al, 1994;Breddam et al, 2000;Dixon et al, 2000;Moreira et al, 2001), and possibly Ar (Trieloff et al, 2000), are isotopically distinct from typical mid-ocean ridge basalt (MORB). Icelandic lavas may also be water-rich compared to the majority of MORB (Nichols et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Sources, degassing, and contamination of CO2, H2O, He, Ne, and Ar in basaltic glasses from Kolbeinsey Ridge, North Atlantic

Macpherson

Hilton

Mertz

et al. 2005

Geochimica et Cosmochimica Acta

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Deep plume origin of the Louisville hotspot: Noble gas evidence

Hanyu

2014

Geochem Geophys Geosyst

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Noble gas compositions have been reported for basaltic core samples from Louisville seamounts recovered during IODP Expedition 330. The in-vacuum crushing techniques were employed to extract noble gases from fresh olivine phenocrysts and submarine glasses with ages between 50 and 74 Ma.Stepwise crushing tests confirmed the extraction of magmatic noble gases from the olivine samples with minimal release of posteruption radiogenic nuclides; however, this was not always the case for the glass samples. The 3 He/ 4 He ratios of the studied samples range from a value similar to those of mid-ocean ridge basalts (MORB) to slightly elevated ratios up to 10.6 Ra. These ratios are not as high as those observed in other ocean island basalts, suggesting that the Louisville mantle plume was weak or the samples represent late-stage magmatic activity of the seamounts. However, two Louisville seamount basalts exhibit a primordial Ne isotopic signature that can be clearly discriminated from MORB Ne ratios. The He and Ne isotopic compositions of the Louisville seamount basalts can be explained by the mixing of less degassed mantle and depleted upper mantle with different He/Ne ratios. The presence of the less degassed mantle component in the source of the Louisville seamounts documents a deep origin of their mantle plume.

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Solar neon in the Icelandic mantle: new evidence for an undegassed lower mantle

Cited by 116 publications

References 37 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

Sources, degassing, and contamination of CO2, H2O, He, Ne, and Ar in basaltic glasses from Kolbeinsey Ridge, North Atlantic

Deep plume origin of the Louisville hotspot: Noble gas evidence

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