Early crust on top of the Earth's core

Tolstikhin, Igor; Hofmann, Albrecht W.

doi:10.1016/j.pepi.2004.05.011

Cited by 180 publications

(102 citation statements)

References 139 publications

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“…This does not rule out a flux of volatile-rich and high 3 He/ 4 He material from a yet deeper geochemical reservoir within the Earth (e.g. Kellogg et al 1999;Porcelli & Halliday 2001;Tolstikhin & Hofmann 2005), but makes any assumption of steady state in a much larger convecting system less certain. Numerical simulations do not need to make an assumption of steady state and are equally capable of balancing such a deep 3 He flux into a convecting mantle system with the observed 3 He/ 4 He and 3 He concentration (e.g.…”

Section: Helium: the Case For An Accretionary Volatile Reservoir In Tmentioning

confidence: 99%

“…The mechanism and timing of formation of this reservoir remain enigmatic. Possible explanations may be dry subduction of a late solar wind-irradiated veneer (Tolstikhin & Hofmann 2005). This would allow for bulk planetary degassing, volatile loss and fractionation of the atmosphere to its current noble gas state independently of arrival.…”

Section: Synthesis and Conclusionmentioning

confidence: 99%

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What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

Ballentine

Holland²

2008

Phil. Trans. R. Soc. A.

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Study of commercially produced volcanic CO 2 gas associated with the Colorado Plateau, USA, has revealed substantial new information about the noble gas isotopic composition and elemental abundance pattern of the mantle. Combined with published data from midocean ridge basalts, it is now clear that the convecting mantle has a maximum 20 Ne/ 22 Ne isotopic composition, indistinguishable from that attributed to solar wind-implanted (SWI) neon in meteorites. This is distinct from the higher 20 Ne/ 22 Ne isotopic value expected for solar nebula gases. The non-radiogenic xenon isotopic composition of the well gases shows that 20 per cent of the mantle Xe is 'solar-like' in origin, but cannot resolve the small isotopic difference between the trapped meteorite 'Q'-component and solar Xe. The mantle primordial 20 Ne/ 132 Xe is approximately 1400 and is comparable with the upper end of that observed in meteorites. Previous work using the terrestrial 129 I-129 Xe mass balance demands that almost 99 per cent of the Xe (and therefore other noble gases) has been lost from the accreting solids and that Pu-I closure age models have shown this to have occurred in the first ca 100 Ma of the Earth's history. The highest concentrations of Q-Xe and solar wind-implanted (SWI)-Ne measured in meteorites allow for this loss and these high-abundance samples have a Ne/Xe ratio range compatible with the 'recycled-aircorrected' terrestrial mantle. These observations do not support models in which the terrestrial mantle acquired its volatiles from the primary capture of solar nebula gases and, in turn, strongly suggest that the primary terrestrial atmosphere, before isotopic fractionation, is most probably derived from degassed trapped volatiles in accreting material.By contrast, the non-radiogenic argon, krypton and 80 per cent of the xenon in the convecting mantle have the same isotopic composition and elemental abundance pattern as that found in seawater with a small sedimentary Kr and Xe admix. These mantle heavy noble gases are dominated by recycling of air dissolved in seawater back into the mantle. Numerical simulations suggest that plumes sampling the core-mantle boundary would be enriched in seawater-derived noble gases compared with the convecting mantle, and therefore have substantially lower 40 Ar/ 36 Ar. This is compatible with observation. The subduction process is not a complete barrier to volatile return to the mantle.

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Section: Helium: the Case For An Accretionary Volatile Reservoir In Tmentioning

confidence: 99%

Section: Synthesis and Conclusionmentioning

confidence: 99%

What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

Ballentine

Holland²

2008

Phil. Trans. R. Soc. A.

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“…There are some proposals that the less degassed portions remain around the core-mantle boundary including the D″ layer (e.g., Kellogg et al, 1999;Samuel and Farnetani, 2003;Tolstikhin and Hofmann, 2005) or the core (Trieloff and Kunz, 2005). If such portions are limited to only the D″ layer which extends to just above a few tens km from the core-mantle boundary (e.g., Loper and Lay, 1995), we have no guarantee whether it can fully explain the observed distribution of the high 3 He/ 4 He all over the world (Fig.…”

Section: Evaluation Of Geochemical Models Based On Noble Gas Signaturesmentioning

confidence: 99%

“…Furthermore, we need to explain why only the D″ layer could retain such primordial components through the Earth's history. Concerning this point, Tolstikhin and Hofmann (2005) have proposed a model that small bodies remained after the collision on the proto-Earth and irradiated by intense solar wind fell on early-formed crust and finally reached the core-mantle-boundary, causing the D″ layer. In this case, we have no guarantee that He and Ne implanted into fragmental materials by the irradiation of the solar wind can be transported to the coremantle boundary without any degassing.…”

Section: Evaluation Of Geochemical Models Based On Noble Gas Signaturesmentioning

confidence: 99%

On the degassing state and the chemical structure of the Earth's interior inferred from noble gas isotopes-Past and recent views

Kaneoka

2008

Geochem. J.

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The degassing state of the Earth's interior is one of the main issues in relation to the evolution of the Earth and has been discussed by many investigators over several decades. I outline some trials to reveal the state of degassing based on noble gas isotopes. Then, based on noble gas isotope signatures so far obtained, I discuss models of the chemical structure of the Earth's interior which are inevitably related to the degassing state of the Earth. I propose a preferred model which suggests the possibility for the occurrence of relatively undegassed and possibly less fractionated reservoir(s) in the Earth's deep interior, which might be located in a relatively non-convective mantle.

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“…; Tolstikhin and Hofmann (2005) ;Tolstikhin 49 et al (2006)). An increase of the radiogenic heat production rate is expected when basaltic 50 material associated with former subducted crust is concentrated in the compositionally dis-51 tinct reservoir (e.g.…”

mentioning

confidence: 97%

Upwellings from a deep mantle reservoir filtered at the 660km phase transition in thermo-chemical convection models and implications for intra-plate volcanism

Summeren¹,

Berg²,

Hilst³

2009

Physics of the Earth and Planetary Interiors

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Please cite this article as: van Summeren, J.R.G., van den Berg, A.P., van der Hilst, R.D., Upwellings from a deep mantle reservoir filtered at the 660 km phase transition in thermo-chemical convection models and implications for intra-plate volcanism, Physics of the Earth and Planetary Interiors (2008), doi:10.1016/j.pepi.2008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Early crust on top of the Earth's core

Cited by 180 publications

References 139 publications

What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

On the degassing state and the chemical structure of the Earth's interior inferred from noble gas isotopes-Past and recent views

Upwellings from a deep mantle reservoir filtered at the 660km phase transition in thermo-chemical convection models and implications for intra-plate volcanism

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Early crust on top of the Earth's core

Cited by 180 publications

References 139 publications

What CO 2 well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

What CO 2 well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

On the degassing state and the chemical structure of the Earth's interior inferred from noble gas isotopes-Past and recent views

Upwellings from a deep mantle reservoir filtered at the 660km phase transition in thermo-chemical convection models and implications for intra-plate volcanism

Contact Info

Product

Resources

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What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere

What CO ₂ well gases tell us about the origin of noble gases in the mantle and their relationship to the atmosphere