Recycling of heavy noble gases by subduction of serpentinite

Krantz, John A.; Parman, S. W.; Kelley, Simon P.

doi:10.1016/j.epsl.2019.06.007

Cited by 16 publications

(16 citation statements)

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“…(5) Trapped Ar correction: Despite the incompatibility of noble gases within the crystal structure of most minerals (e.g., Kelley, 2002;Jackson et al, 2015;Krantz et al, 2019), nonradiogenic 40 Ar, co-located with 38 Ar and 36 Ar, is hosted in mineral and melt inclusions, found in trace quantities in crystal lattices, and adsorbed on mineral surfaces. On Earth and Mars, Ar is a major constituent of the atmosphere, and atmospheric Ar is often observed during sample degassing (e.g., Bogard and Johnson, 1983;Walton et al, 2007).…”

Section: Data Corrections and Factors Contributing To Uncertaintiesmentioning

confidence: 99%

Interpreting and reporting 40Ar/39Ar geochronologic data

et al. 2020

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The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%, thereby providing precise time constraints for a wide range of geologic and extraterrestrial processes. Analyses of increasingly smaller subsamples have revealed age dispersion in many materials, including some minerals used as neutron fluence monitors. Accordingly, interpretive strategies are evolving to address observed dispersion in dates from a single sample. Moreover, inferring a geologically meaningful “age” from a measured “date” or set of dates is dependent on the geological problem being addressed and the salient assumptions associated with each set of data. We highlight requirements for collateral information that will better constrain the interpretation of 40Ar/39Ar data sets, including those associated with single-crystal fusion analyses, incremental heating experiments, and in situ analyses of microsampled domains. To ensure the utility and viability of published results, we emphasize previous recommendations for reporting 40Ar/39Ar data and the related essential metadata, with the amendment that data conform to evolving standards of being findable, accessible, interoperable, and reusable (FAIR) by both humans and computers. Our examples provide guidance for the presentation and interpretation of 40Ar/39Ar dates to maximize their interdisciplinary usage, reproducibility, and longevity.

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Section: Data Corrections and Factors Contributing To Uncertaintiesmentioning

confidence: 99%

Interpreting and reporting 40Ar/39Ar geochronologic data

et al. 2020

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“…Our identification of a very heavy iron component in the altered mantle of subducting slabs was not explicitly considered but nonetheless supports this model. The recycling of serpentinized peridotite in subducted oceanic lithosphere is increasingly being recognized as an important influx to the convecting mantle (2,(4)(5)(6)(7)(8)(9). Iron isotopic compositions allow tracing of the subduction-driven geochemical pathway from surface processes such as seafloor serpentinization to the depths of the mantle transition zone and lower mantle.…”

Section: Implications Of Recycled Heavy Ironmentioning

confidence: 99%

“…However, the signature of the serpentinized peridotitic portion of these recycled slabs has only been inferred indirectly, based on the geochemistry of oceanic basalts, erupted at ocean islands and mid-ocean ridges. Such basalts contain water and halogens ( 4 ), as well as noble gases ( 8 ), that suggest that their mantle sources are marked by extensive long-term subduction of serpentinized peridotite.…”

Section: Introductionmentioning

confidence: 99%

Heavy iron in large gem diamonds traces deep subduction of serpentinized ocean floor

Smith

Shirey

et al. 2021

Sci. Adv.

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Subducting tectonic plates carry water and other surficial components into Earth’s interior. Previous studies suggest that serpentinized peridotite is a key part of deep recycling, but this geochemical pathway has not been directly traced. Here, we report Fe-Ni–rich metallic inclusions in sublithospheric diamonds from a depth of 360 to 750 km with isotopically heavy iron (δ56Fe = 0.79 to 0.90‰) and unradiogenic osmium (187Os/188Os = 0.111). These iron values lie outside the range of known mantle compositions or expected reaction products at depth. This signature represents subducted iron from magnetite and/or Fe-Ni alloys precipitated during serpentinization of oceanic peridotite, a lithology known to carry unradiogenic osmium inherited from prior convection and melt depletion. These diamond-hosted inclusions trace serpentinite subduction into the mantle transition zone. We propose that iron-rich phases from serpentinite contribute a labile heavy iron component to the heterogeneous convecting mantle eventually sampled by oceanic basalts.

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“…He, Ne and Ar occupy ring sites in amphibole [37], a mineral formed in the altered oceanic crust, and experimentally measured solubilities are up to four orders of magnitude higher than for other silicates at similar run P (0.17 GPa). Ring sites are formed by a pair of opposing six-membered (Si,Al)O 4− 4 tetrahedra rings, with a ring inner diameter circa 5 Å. Noble gases sitting in these sites are thus surrounded by 12 neighboring oxygens at approximately 2.5 Å. Kr and Xe solubilities have not been investigated in amphibole, but are even higher than Ar solubility in serpentine (×2 for Kr, ×10 for Xe), another important mineral from the altered oceanic crust [39].…”

Section: Clathrates and Other Cage Compoundsmentioning

confidence: 99%

Noble Gas Reactivity in Planetary Interiors

Sanloup

2020

Front. Phys.

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While the field of noble gas reactivity essentially belongs to chemistry, Earth and planetary sciences have brought a different perspective to the field. Indeed, planetary interiors are natural high pressure (P) and high temperature (T) laboratories, where conditions exist where bonding of the heaviest noble gases may be induced thermodynamically through volume reduction (Le Châtelier's principle). Earth and planetary sciences besides generate numerous and precise observations such as the depletion of the terrestrial and martian atmospheres in xenon, pointing to the potential for Xe to be sequestered at depth, potentially induced by its reactivity. More generally, this paper will review the advances on noble gas reactivity at the extreme P-T conditions found within planetary interiors from experiments and theoretical investigations. This review will cover the synthesis of cage compounds, stoichiometric oxides and metals, and non-stoichiometric compounds where noble gases are only minor or trace elements but could be essential in solving some Earth and planetary puzzles. An apparent trend in noble gas reactivity with P emerges. In the case of Xe which is the most documented, metals are synthesized above 150 GPa, i.e., at terrestrial core conditions, stoichiometric Xe-oxides between 50 and 100 GPa, i.e., in the P-T range of the Earth's lower mantle, but Xe-O high energy bonds may also form under the modest pressures of the Earth's crust (<1 GPa) in non-stoichiometric compounds. Most planetary relevant noble gas compounds found are with xenon, with only a few predicted helium compounds, the latter having no or very little charge transfer between helium and neighboring atoms.

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Recycling of heavy noble gases by subduction of serpentinite

Cited by 16 publications

References 51 publications

Interpreting and reporting 40Ar/39Ar geochronologic data

Interpreting and reporting 40Ar/39Ar geochronologic data

Heavy iron in large gem diamonds traces deep subduction of serpentinized ocean floor

Noble Gas Reactivity in Planetary Interiors

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