Noble Gases as Tracers of Mantle Processes and Magmatic Degassing

Moreira, Manuel; Kurz, Mark D.

doi:10.1007/978-3-642-28836-4_12

Cited by 28 publications

(27 citation statements)

References 190 publications

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“…The mantle 3 He/ 22 Ne ratio is not known precisely. It is between 5 and 10 for the upper mantle (Moreira et al, ; Tucker & Mukhopadhyay, ) and around 2 for the Galápagos and Iceland mantle sources (e.g., Kurz et al, ; Moreira & Kurz, ; Mukhopadhyay, ; Péron et al, ; Tucker & Mukhopadhyay, ). It seems even lower for samples from West Greenland, assumed to represent the protoicelandic plume (Graham et al, ).…”

Section: Compilation Of Mantle Lunar Soils Idps Micrometeorites Amentioning

confidence: 99%

Origin of Light Noble Gases (He, Ne, and Ar) on Earth: A Review

Péron

Moreira

Agranier

2018

Geochem Geophys Geosyst

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We review the different scenarios for the origin of light noble gases (He, Ne, and Ar) on Earth. Several sources could have contributed to the Earth's noble gas budget: implanted solar wind, solar nebula gas, chondrites, and comets. Although there is evidence for “solar‐like” neon in the Earth's mantle, questions remain as to its origin. A new compilation of noble gas data in lunar soils, interplanetary dust particles, micrometeorites, and solar wind allows examination of the implanted solar wind composition, which is key to understanding the “solar‐like” mantle neon isotope composition. We show that lunar soils that reflect this solar‐wind‐implanted signature have a 20Ne/22Ne ratio very close to that of ocean island basalts. New data and calculations illustrate that the measured plume source 20Ne/22Ne ratio is close to the primitive mantle ratio, when taking into account mixing with the upper mantle (that has lower 20Ne/22Ne ratio). This favors early solar wind implantation to account for the origin of light volatiles (He, Ne, and possibly H) in the Earth's mantle: they were incorporated by solar wind irradiation into the Earth's precursor grains during the first few Myr of the solar system's formation. These grains must have partially survived accretion processes (only a few percent are needed to satisfy the Earth's budget of light volatiles). As for the atmosphere, the neon isotope composition can be explained by mixing 36% of mantle gases having this solar‐wind‐implanted signature and 64% of chondritic gases delivered in a late veneer phase.

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Section: Compilation Of Mantle Lunar Soils Idps Micrometeorites Amentioning

confidence: 99%

Origin of Light Noble Gases (He, Ne, and Ar) on Earth: A Review

Péron

Moreira

Agranier

2018

Geochem Geophys Geosyst

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“…Hence, these results highlight the large contrast between MORB and OIB (Moreira and Kurz, 2013). The MORB source is characterized with a 3 He/ 22 Ne ratio of at least 5 (Moreira et al, 1998;Tucker and Mukhopadhyay, 2014) and a 3 He/ 36 Ar ratio of 0.45 (Moreira et al, 1998;Raquin et al, 2008).…”

Section: Elemental Ratiosmentioning

confidence: 80%

“…The linear correlations observed allow extrapolation of the 3 He/ 22 Ne and 3 He/ 36 Ar ratios respectively for the 20 Ne/ 22 Ne and 40 Ar/ 36 Ar ratios determined by the analyses (section 3.2). Such a method is consistent only for samples having a 4 He/ 40 Ar * ratio similar to the production ratio (Moreira and Kurz, 2013) so that elemental fractionation between noble gases (e.g. by degassing) is very unlikely to have occurred.…”

Section: Neon and Argon Isotopic Ratiosmentioning

confidence: 96%

“…Indeed, 4 He and 40 Ar * are two radiogenic isotopes produced by the decay of 235 U, 238 U and 232 Th for helium and by the decay of 40 K for argon, and the (U + Th)/K ratio is relatively homogeneous in the lower mantle (Arevalo et al, 2009). The 4 He/ 40 Ar * production ratio varies from 2 to 5 (Moreira and Kurz, 2013). Since helium is nine times more soluble in a tholeiitic melt than argon (Jambon et al, 1986), helium and argon would be fractionated if a magma was degassed during its ascent to the surface, leading to a higher 4 He/ 40 Ar * ratio than the production ratio.…”

Section: Helium and Radiogenic Argonmentioning

confidence: 98%

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Neon isotopic composition of the mantle constrained by single vesicle analyses

Péron

Moreira

Colin

et al. 2016

Earth and Planetary Science Letters

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“…For comparison, 20 Ne/ 22 Ne results are within the range of 20 Ne/ 22 Ne ratios obtained on metamorphic diamonds from the Kokchetav UHP massif of Kazakhstan (21), with the exception of one phengite analysis (Phg-1; 1,500°C step). No evidence for trapped mantle-derived 20 Ne/ 22 Ne [either solar or neon B (40,41)] was obtained, despite mantle eNd and eHf values obtained on garnet from the same coesite eclogite (29).…”

Section: Ar and Ne In Phengite And Omphacitementioning

confidence: 92%

Atmospheric Ar and Ne returned from mantle depths to the Earth’s surface by forearc recycling

Baldwin¹,

Das²

2015

Proc. Natl. Acad. Sci. U.S.A.

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In subduction zones, sediments, hydrothermally altered lithosphere, fluids, and atmospheric gases are transported into the mantle, where ultrahigh-pressure (UHP) metamorphism takes place. However, the extent to which atmospheric noble gases are trapped in minerals crystallized during UHP metamorphism is unknown. We measured Ar and Ne trapped in phengite and omphacite from the youngest known UHP terrane on Earth to determine the composition of Ar and Ne returned from mantle depths to the surface by forearc recycling. An 40 Ar/ 39 Ar age [7.93 ± 0.10 My (1σ)] for phengite is interpreted as the timing of crystallization at mantle depths and indicates that 40 Ar/ 39 Ar phengite ages reliably record the timing of UHP metamorphism. Both phengite and omphacite yielded atmospheric 38 Ar/ 36 Ar and 20 Ne/ 22 Ne. Our study provides the first documentation, to our knowledge, of entrapment of atmospheric Ar and Ne in phengite and omphacite. Results indicate that a subduction barrier for atmosphericderived noble gases does not exist at mantle depths associated with UHP metamorphism. We show that the crystallization age together with the isotopic composition of nonradiogenic noble gases trapped in minerals formed during subsolidus crystallization at mantle depths can be used to unambiguously assess forearc recycling of atmospheric noble gases. The flux of atmospheric noble gas entering the deep Earth through subduction and returning to the surface cannot be fully realized until the abundances of atmospheric noble gases trapped in exhumed UHP rocks are known.subduction | UHP metamorphism | geochronology | noble gas | atmosphere

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Noble Gases as Tracers of Mantle Processes and Magmatic Degassing

Cited by 28 publications

References 190 publications

Origin of Light Noble Gases (He, Ne, and Ar) on Earth: A Review

Origin of Light Noble Gases (He, Ne, and Ar) on Earth: A Review

Neon isotopic composition of the mantle constrained by single vesicle analyses

Atmospheric Ar and Ne returned from mantle depths to the Earth’s surface by forearc recycling

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