Rare Gas Systematics in Popping Rock: Isotopic and Elemental Compositions in the Upper Mantle

Moreira, Manuel; Kunz, Joachim; Allègre, Claude J.

doi:10.1126/science.279.5354.1178

Cited by 352 publications

(218 citation statements)

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“…Farley & Poreda (1993) noted that the mantle value appeared to 'top out' at 20 Ne/ 22 NeZ12.5 but, owing to limited data, did not place any significance on this value. More recently, variable 40 Ar/ 36 Ar for a constant maximum 20 Ne/ 22 NeZ12.5 from both Iceland and Loihi (Hawaiian seamount) and newer high-quality MORB data (Moreira et al 1998) were used to argue for a SWI origin for the Ne in the mantle (Trieloff et al 2000). It was not possible, however, to rule out a ubiquitous air component mixing with solar wind with a higher 20 Ne/ 22 Ne Trieloff et al 2001).…”

Section: Neon: a Trapped Meteorite Origin For Terrestrial Mantle Volamentioning

confidence: 99%

“…We can estimate the MORB-source mantle 40 Ar concentration from the mantle 3 He/ 40 Ar defined from well gases and MORB (Moreira et al 1998;Ballentine et al 2005) and the 3 He mantle concentration derived above. If we take the whole mantle to have this 40 Ar concentration, the total 40 Ar in the atmosphere and the mantle combined is significantly less than the total amount of 40 Ar estimated to have been produced since the Earth's accretion.…”

Section: Argon: a Note On Mantle Degassingmentioning

confidence: 99%

“…Pepin & Porcelli 2006), but all converge on a closure age for terrestrial volatile loss at ca 80 Ma after Solar System formation. It should Ne/ 22 NeZ12.5 (Moreira et al 1998), Bravo Dome well-gas 'mantle' (Holland & Ballentine 2006) and ocean sediments (Matsuda & Nagao 1986 Pu-derived Xe) in the convecting mantle (MORB-source) and atmosphere are identical-it is not possible to resolve closure of one reservoir from the other (Pepin & Porcelli 2006). Critically for this work, from I-Pu systematics, it can be calculated that the silicate Earth has lost almost 99 per cent of its Xe and therefore other noble gases during the accretionary process .…”

Section: Xenon: Massive Early Planetary Volatile Loss and Fractionationmentioning

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: Neon: a Trapped Meteorite Origin For Terrestrial Mantle Volamentioning

confidence: 99%

Section: Argon: a Note On Mantle Degassingmentioning

confidence: 99%

Section: Xenon: Massive Early Planetary Volatile Loss and Fractionationmentioning

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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“…These two equations are valid for the MORB source (or shallow mantle, SM) and we assume that such a source corresponds to a mass fraction of ancient crust, , of 8% and helium concentrations of 120 10¢ (Moreira et al, 1998)). We further assume that the ancient crust is 1.5 byrs old and contains 70 ppb U, similar to modern MORBs.…”

Section: A Whole Mantle Marble Cake Modelmentioning

confidence: 99%

Geophysical and geochemical models of mantle convection: Successes and future challenges

Ricard¹,

Coltice²

2004

Geophysical Monograph Series

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Abstract. Although more and more robust evidence for whole mantle convection comes from seismic tomography and geoid modeling, the rare gases and other isotopic or trace element signatures of ridge and hotspot basalts indicate the presence of various isolated geochemical reservoirs in the mantle. We discuss this discrepancy between fluid dynamic views of mantle convection and chemical observations. We compare the standard model of geodynamicists where the mantle behaves as a fluid mostly heated from within with the findings of seismic tomography. We suggest that a significant part of the subducted oceanic crust transforms into dense eclogitic assemblages, and partially segregates to form a layer that has grown with time above the Core Mantle Boundary (CMB) and should correspond to the D" layer of seismological models ( 280 km thick). We show how a two component marble cake mantle filling the whole mantle except D" can account for the variability of Ocean Island Basalts (OIB) and Mid-Ocean Ridge Basalts (MORB) in rare gases. We then present the state of the art in thermochemical convection of the mantle and emphasize the numerical and conceptual progress that must be made to provide a quantitative test of the geochemical hypotheses.

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“…The 3 He abundance in DMM calculated with the continuous depletion model is within a factor of 3 to 20 of the 3 He abundances inferred from MORB samples and 3 He flux from ridges (see Ballentine et al [2002] for summary). Assuming 10% melting of the mantle source, 3 He concentrations for DMM were derived from CO 2 concentrations and canonical mantle CO 2 / 3 He ratios in MORB melt inclusions (4.52×10 8 ±1.93 atoms 3 He/g (Saal et al, 2002), "popping" rock (>2.69×10 9 atoms 3 He /g [Moreira et al, 1998]), and flux of 3 He out of mid-ocean ridges (1.18×10 9 atoms 3 He /g [Farley et al, 1995;Ballentine et al, 2002]). …”

Section: Appendix B: Helium Isotope Modelmentioning

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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Rare Gas Systematics in Popping Rock: Isotopic and Elemental Compositions in the Upper Mantle

Cited by 352 publications

References 40 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

Geophysical and geochemical models of mantle convection: Successes and future challenges

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

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Rare Gas Systematics in Popping Rock: Isotopic and Elemental Compositions in the Upper Mantle

Cited by 352 publications

References 40 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

Geophysical and geochemical models of mantle convection: Successes and future challenges

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

Contact Info

Product

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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