The solid Earth is widely believed to have lost its original gases through a combination of early catastrophic release and regulated output over geologic time. In principle, the abundance of 40Ar in the atmosphere represents the time-integrated loss of gases from the interior, thought to occur through partial melting in the mantle followed by melt ascent to the surface and gas exsolution. Here we present data that reveal two major difficulties with this simple magmatic degassing scenario—argon seems to be compatible in the major phases of the terrestrial planets, and argon diffusion in these phases is slow at upper-mantle conditions. These results challenge the common belief that the upper mantle is nearly degassed of 40Ar, and they call into question the suitability of 40Ar as a monitor of planetary degassing. An alternative to magmatism is needed to release argon to the atmosphere, with one possibility being hydration of oceanic lithosphere consisting of relatively argon-rich olivine and orthopyroxene.
This is a preview of subscription content, access via your institution
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Staudacher, T. & Allègre, C. J. Terrestrial xenology. Earth Planet. Sci. Lett. 60, 389–406 (1982)
Jacobsen, S. B. The Hf-W system and the origin of the Earth and Moon. Annu. Rev. Earth Planet. Sci. 33, 531–570 (2005)
Halliday, A. N. & Kleine, T. in Meteorites and the Early Solar System II (eds Lauretta, D., Leshin, L. & McSween, H. Jr) 775–801 (Univ. Arizona Press, Tucson, 2006)
Boyet, M. & Carlson, R. W. 142Nd evidence for early (>4.53 Ga) global differentiation of the silicate Earth. Science 309, 576–581 (2005)
Kurz, M. D., Jenkins, W. J. & Hart, S. R. Helium isotopic systematics of ocean islands and mantle heterogeneity. Nature 297, 43–46 (1982)
Jochum, K. P., Hofmann, A. W., Ito, E., Seufert, H. M. & White, W. M. K, U and Th in mid-ocean ridge basalt glasses and heat production, K/U and K/Rb in the mantle. Nature 306, 431–436 (1983)
Davies, G. F. Geophysically constrained mantle mass flows and the 40Ar budget: a degassed lower mantle? Earth Planet. Sci. Lett. 166, 149–162 (1999)
van der Hilst, R. D., Widiyantoro, S. & Engdahl, E. R. Evidence for deep mantle circulation from global tomography. Nature 386, 578–584 (1997)
Anderson, D. L. The statistics and distribution of helium in the mantle. Int. Geol. Rev. 42, 289–311 (2001)
Parman, S. W., Kurz, M. D., Hart, S. R. & Grove, T. L. Helium solubility in olivine and implications for high 3He/4He in ocean island basalts. Nature 437, 1140–1143 (2005)
Porcelli, D. & Turekian, K. K. The history of planetary degassing as recorded by noble gases. Treatise Geochem. 4, 281–318 (2006)
Porcelli, D. & Ballentine, C. J. in Noble Gases in Geochemistry and Cosmochemistry (eds Porcelli, D. Ballentine, C. J. & Wieler, R.) Rev. Mineral. Geochem. 47, 411–480 (2002)
Klein, E. M. & Langmuir, C. H. Global correlations of ocean ridge basalt chemistry with axial depth and crustal thickness. J. Geophys. Res. 92 (B8). 8089–8115 (1987)
Hellebrand, E., Snow, J. E., Dick, H. J. B. & Hofmann, A. W. Coupled major and trace elements as indicators of the extent of melting in mid-ocean-ridge peridotites. Nature 410, 677–681 (2001)
Watson, E. B. & Cherniak, D. J. Lattice diffusion of Ar in quartz, with constraints on Ar solubility and evidence of nanopores. Geochim. Cosmochim. Acta 67, 2043–2062 (2003)
Thomas, J. B., Cherniak, D. J. & Watson, E. B. Lattice diffusion and solubility of Ar in forsterite, enstatite, periclase, quartz and corundum. Chem. Geol. (submitted)
Tsuchiyama, A. & Kawamura, K. in Noble Gas Geochemistry and Cosmochemistry (ed. Matsuda, J.) 315–323 (Terra Scientific Publishing, Tokyo, 1994)
Jambon, A., Weber, H. & Braun, O. Solubility of He, Ne, Ar, Kr and Xe in a basalt melt in the range 1250–1600°C. Geochemical implications. Geochim. Cosmochim. Acta 50, 401–408 (1986)
Lux, G. The behavior of noble gases in silicate liquids: Solution, diffusion, bubbles, and surface effects, with applications to natural samples. Geochim. Cosmochim. Acta 51, 1549–1560 (1987)
White, B. S., Brearley, M. & Montana, A. Solubility of argon in silicate liquids at high pressures. Am. Mineral. 74, 513–529 (1989)
Broadhurst, C. L. & Drake, M. J. Hagee, B. E. & Bernatowicz, T. J. Solubility and partitioning of Ar in anorthite, diopside, forsterite, spinel, and synthetic basalt. Geochim. Cosmochim. Acta 54, 299–309 (1990)
Carroll, M. R. & Stolper, E. M. Noble gas solubility in silicate melts and glasses: New experimental results for Ar and the relationship between solubility and ionic porosity. Geochim. Cosmochim. Acta 57, 5039–5051 (1993)
Shibata, T., Takahashi, E. & Matsuda, J. Solubility of neon, argon, krypton, and xenon in binary and ternary silicate systems. Geochim. Cosmochim. Acta 62, 1241–1253 (1998)
Schmidt, B. C. & Keppler, H. Experimental evidence of high noble gas solubility in silicate melts under mantle pressures. Earth Planet. Sci. Lett. 195, 277–290 (2002)
Batiza, R., Bernatowicz, T. J., Hohenberg, C. M. & Podosek, F. A. Relations of noble gas abundances to petrogenesis and magmatic evolution of oceanic basalts and related differentiated volcanic rocks. Contrib. Mineral. Petrol. 69, 301–313 (1979)
Hiyagon, H. & Ozima, M. Noble gas distribution between basalt melt and crystals. Earth Planet. Sci. Lett. 58, 255–264 (1982)
Hiyagon, H. & Ozima, M. Partition of noble-gases between olivine and basalt melt. Geochim. Cosmochim. Acta 50, 2045–2057 (1986)
Brooker, R. A. et al. The “zero-charge” partitioning behaviour of noble gases during mantle melting. Nature 423, 738–741 (2003)
Marty, B. & Lussiez, P. Constraints on rare gas partition coefficients from analysis of olivine-glass from a picritic mid-ocean ridge basalt. Chem. Geol. 106, 1–7 (1993)
Valbracht, P. J., Honda, M., Staudigel, H., McDougall, I. & Trost, A. P. in Nobel Gas Geochemistry and Cosmochemistry (ed. Matsuda, J.) 373–381 (Terra Scientific, Tokyo, 1994)
Poreda, R. J. & Farley, K. A. Rare gases in Samoan xenoliths. Earth Planet. Sci. Lett. 113, 129–144 (1992)
McDougall, I. & Green, D. H. Excess radiogenic argon in pyroxene and isotopic ages on minerals from Norwegian eclogites. Norsk Geol. Tidss 44, 183–196 (1964)
Harrison, T. M. & McDougall, I. Excess argon in metamorphic rocks from Broken Hill, New South Wales: Implications for 40Ar/39Ar age spectra and the thermal history of the region. Earth Planet. Sci. Lett. 55, 123–149 (1981)
Lanphere, M. A. & Dalrymple, G. B. Identification of excess 40Ar by the 40Ar/39Ar age spectrum technique. Earth Planet. Sci. Lett. 32, 141–148 (1976)
Hart, S. R. Equilibration during mantle melting: a fractal tree model. Proc. Natl Acad. Sci. USA 90, 11914–11918 (1993)
Iwamori, H. A model for disequilibrium mantle melting incorporating melt transport by porous and channel flows. Nature 366, 734–737 (1993)
Spiegleman, M. & Kenyon, P. The requirements for chemical disequilibrium during magma migration. Earth Planet. Sci. Lett. 109, 611–620 (1992)
Cherniak, D. J. & Liang, Y. Rare earth element diffusion in natural enstatite. Geochim. Cosmochim. Acta 71, 1324–1340 (2007)
Li, X.-P., Rahn, M. & Bucher, K. Serpentinites of the Zermatt-Saas ophiolite complex and their texture evolution. J. Metamorph. Geol 22, 139–177 (2004)
Korenaga, J. Thermal cracking and the deep hydration of the oceanic lithosphere: A key to the generation of plate tectonics. J. Geophys. Res. 112 B05408 doi: 10.1029/2006JB004502 (2007)
Rudnick, R. L. & Fountain, D. M. Nature and composition of the continental crust: a lower crustal perspective. Rev. Geophys. 33, 267–309 (1995)
Allègre, C. J., Staudacher, T. & Sarda, P. Rare gas systematics: formation of the atmosphere, evolution and structure of the Earth’s mantle. Earth Planet. Sci. Lett. 81, 127–150 (1986)
Lassiter, J. C. Role of recycled oceanic crust in the potassium and argon budget of the Earth: toward a resolution of the “missing argon” problem. Geochem. Geophys. Geosyst. 5 doi: 10.1029/2004GC000711 (2004)
Murthy, V. R., van Westrenen, W. & Fei, Y. Experimental evidence that potassium is a substantial radioactive heat source in the planetary cores. Nature 426, 163–165 (2003)
Armstrong, R. L. The persistent myth of crustal growth. Aust. J. Earth Sci. 38, 613–630 (1991)
Turekian, K. K. The parameters controlling planetary degassing based on 40Ar systematics. In From Mantle to Meteorites (ed. Gopalan, K.) 147–152 (Indian Academy of Sciences, Bangalore, 1990)
McDougall, I. & Harrison, T. M. Geochronology and Thermochronology by the 40Ar/39Ar Method 1–269 (Oxford Univ. Press, New York, 1999)
Burnard, P. Diffusive fractionation of noble gases and helium isotopes during mantle melting. Earth Planet. Sci. Lett. 220, 287–295 (2004)
We are grateful to F. M. Richter and K. K. Turekian for discussions about noble gas systematics and bulk-Earth model constraints, and to M. J. Drake for comments. This research was supported by the NSF.
Author Contributions E.B.W. ran exploratory experiments, developed the melting models and wrote the manuscript; J.B.T. performed most of the experiments and interpreted the data; D.J.C. conducted the Rutherford backscattering spectroscopy analyses and reduced the raw spectra.
Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.
About this article
Cite this article
Watson, E., Thomas, J. & Cherniak, D. 40Ar retention in the terrestrial planets. Nature 449, 299–304 (2007). https://doi.org/10.1038/nature06144
This article is cited by
Loss and Fractionation of Noble Gas Isotopes and Moderately Volatile Elements from Planetary Embryos and Early Venus, Earth and Mars
Space Science Reviews (2020)
Nature Geoscience (2013)
Primary and secondary processes constraining the noble gas isotopic signatures of carbonatites and silicate rocks from Brava Island: evidence for a lower mantle origin of the Cape Verde plume
Contributions to Mineralogy and Petrology (2012)