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The Chondritic Moon: a solution to the 142Nd conundrum and implications for terrestrial mantle evolution

Published online by Cambridge University Press:  08 January 2016

ALAN P. DICKIN*
Affiliation:
School of Geography & Earth Sciences, McMaster University, Hamilton, Ontario, L8S 1K8, Canada
*

Abstract

Recent discoveries that the Earth has a supra-chondritic 142Nd signature have thrown chondritic geochemical Earth models into doubt. Several solutions have been proposed to explain this discrepancy but none has been widely accepted. This paper reviews Nd isotope data for the Moon which bridge the gap between the 142Nd signatures of chondritic meteorites and the accessible Earth. Different chondrite classes define a 142Nd–148Nd correlation line attributed to incomplete mixing of nucleosynthetic components in the solar nebula. Terrestrial standards have 142Nd signatures well above this correlation line, but the 142Nd signature of the Bulk Moon is c. 6 ppm lower than terrestrial (assuming a chondritic Sm/Nd ratio) and falls within error of enstatite chondrites. In view of the demonstrated isotopic similarity between the Earth and Moon, giant impact models require the Moon to be a sample of the early Earth. Therefore, it is inferred that the Earth–Moon system was generated from material similar to enstatite chondrites, but Earth's mantle experienced Sm/Nd fractionation very soon after the Moon-forming collision. Such fractionation processes have been attributed to subduction of early Fe-enriched crust into a deep mantle storage reservoir. Because Sm/Nd fractionation occurred when most 146Sm had already decayed, the hidden incompatible-element-enriched reservoir only became slightly depressed in its 142Nd signature, explaining why this signal has not yet been detected in ocean island basalt sources.

Type
Rapid Communication
Copyright
Copyright © Cambridge University Press 2016 

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References

Akram, W., Schönbächler, M., Bisterzo, S. & Gallino, R. 2015. Zirconium isotope evidence for the heterogeneous distribution of s-process materials in the solar system. Geochimica et Cosmochimica Acta 165, 484500.Google Scholar
Andreasen, R. & Sharma, M. 2006. Solar nebula heterogeneity in p-process samarium and neodymium isotopes. Science 314, 806–9.CrossRefGoogle ScholarPubMed
Andreasen, R. & Sharma, M. 2007. Mixing and homogenization in the early solar system: clues from Sr, Ba, Nd and Sm isotopes in meteorites. Astrophysical Journal 665, 874–83.Google Scholar
Andreasen, R., Sharma, M., Subbarao, K. V. & Viladkar, S. G. 2008. Where on Earth is the enriched Hadean reservoir? Earth and Planetary Science Letters 266, 1428.Google Scholar
Borg, L. E., Gaffney, A. M. & Shearer, C. K. 2015. A review of lunar chronology revealing a preponderance of 4.34–4.37 Ga ages. Meteoritics & Planetary Science 50, 715–32.Google Scholar
Bouvier, A., Vervoort, J. D. & Patchett, P. J. 2008. The Lu-Hf and Sm-Nd isotopic composition of CHUR: constraints from unequilibrated chondrites and implications for the bulk composition of terrestrial planets. Earth and Planetary Science Letters 273, 4857.Google Scholar
Boyet, M. & Carlson, R. W. 2005. 142Nd evidence for early (>4.53 Ga) global differentiation of the silicate Earth. Science 309, 576–81.CrossRefGoogle ScholarPubMed
Boyet, M. & Carlson, R. W. 2006. A new geochemical model for the Earth's mantle inferred from 146Sm–142Nd systematics. Earth and Planetary Science Letters 250, 254–68.Google Scholar
Boyet, M. & Carlson, R. W. 2007. A highly depleted moon or a non-magma ocean origin for the lunar crust? Earth and Planetary Science Letters 262, 505–16.CrossRefGoogle Scholar
Boyet, M. & Gannoun, A. 2013. Nucleosynthetic Nd isotope anomalies in primitive enstatite chondrites. Geochimica et Cosmochimica Acta 121, 652–66.CrossRefGoogle Scholar
Brandon, A. D., Lapen, T. J., Debaille, V., Beard, B. L., Rankenburg, K. & Neal, C. 2009. Re-evaluating 142Nd/144Nd in lunar mare basalts with implications for the early evolution and bulk Sm/Nd of the Moon. Geochimica et Cosmochimica Acta 73, 6421–45.Google Scholar
Burkhardt, C., Kleine, T., Oberli, F., Pack, A., Bourdon, B. & Wieler, R. 2011. Molybdenum isotope anomalies in meteorites: constraints on solar nebula evolution and origin of the Earth. Earth and Planetary Science Letters 312, 390400.Google Scholar
Canup, R. M. 2012. Forming a moon with an earth-like composition via a giant impact. Science 338, 1052–5.CrossRefGoogle Scholar
Carlson, R. W., Boyet, M. & Horan, M. 2007. Chondrite barium, neodymium, and samarium isotopic heterogeneity and early Earth differentiation. Science 316, 1175–8.Google Scholar
Caro, G. & Bourdon, B. 2010. Non-chondritic Sm/Nd ratio in the terrestrial planets: consequences for the geochemical evolution of the mantle-crust system. Geochimica et Cosmochimica Acta 74, 3333–49.Google Scholar
Caro, G., Bourdon, B., Halliday, A. N. & Quitte, G. 2008. Super-chondritic Sm/Nd ratios in Mars, the Earth and the Moon. Nature 452, 336–9.Google Scholar
Chase, C. G. & Patchett, P. J. 1988. Stored mafic/ultramafic crust and early Archean mantle depletion. Earth and Planetary Science Letters 91, 6672.Google Scholar
Cuk, M. & Stewart, S. T. 2012. Making the Moon from a fast-spinning Earth: a giant impact followed by resonant despinning. Science 338, 1047–52.Google Scholar
Dauphas, N., Chen, J. H., Zhang, J., Papanastassiou, D. A., Davis, A. M. & Travaglio, C. 2014. Calcium-48 isotopic anomalies in bulk chondrites and achondrites: evidence for a uniform isotopic reservoir in the inner protoplanetary disk. Earth and Planetary Science Letters 407, 96108.Google Scholar
Dauphas, N., Marty, B. & Reisberg, L. 2002. Inference on terrestrial genesis from molybdenum isotope systematics. Geophysics Research Letters 29 (6), doi: 10.1029/2001GL014237, 3 pp.Google Scholar
DePaolo, D. J. 1981. Neodymium isotopes in the Colorado Front Range and crust-mantle evolution in the Proterozoic. Nature 291, 193–6.Google Scholar
Foley, C. N., Wadhwa, M., Borg, L. E., Janney, P. E., Hines, R. & Grove, T. L. 2005. The early differentiation of Mars from 182W–142Nd isotope systematics in the SNC meteorites. Geochimica et Cosmochimica Acta 69, 4557–71.Google Scholar
Gannoun, A., Boyet, M., Rizo, H. & El Goresy, A. 2011. 146Sm–142Nd systematics measured in enstatite chondrites reveals a heterogeneous distribution of 142Nd in the solar nebula. Proceedings of the National Academy of Sciences 108, 7693–7.Google Scholar
Halliday, A. N. 2004. Mixing, volatile loss and compositional change during impact-driven accretion of the Earth. Nature 427, 505–9.CrossRefGoogle ScholarPubMed
Halliday, A. N. 2012. The origin of the Moon. Science 338, 1040–1.Google Scholar
Hart, S. R., Hauri, E. H., Oschmann, L. A. & Whitehead, J. A. 1992. Mantle plumes and entrainment: isotopic evidence. Science 256, 517–20.Google Scholar
Huang, S., Jacobsen, S. B. & Mukhopadhyay, S. 2013. 147Sm–143Nd systematics of Earth are inconsistent with a superchondritic Sm/Nd ratio. Proceedings of the National Academy of Sciences 110, 4929–34.Google Scholar
Jackson, M. G. & Carlson, R. W. 2012. Homogeneous superchondritic 142Nd–144Nd in the mid-ocean ridge basalt and ocean island basalt mantle. Geochemistry, Geophysics, Geosystems 13, 110.Google Scholar
Jacobsen, S. B. & Wasserburg, G. J. 1979. The mean age of mantle and crustal reservoirs. Journal of Geophysical Research 84, 7411–27.Google Scholar
Javoy, M., Kaminski, E., Guyot, F., Andrault, D., Sanloup, C., Moreira, M., Labrosse, S., Jambon, A., Agrinier, P., Davaille, A. & Jaupart, C. 2010. The chemical composition of the Earth: enstatite chondrite models. Earth and Planetary Science Letters 293, 259–68.Google Scholar
Kleine, T., Münker, C., Mezger, K. & Palme, H. 2002. Rapid accretion and early core formation on asteroids and the terrestrial planets from Hf–W chronometry. Nature 418, 952–5.Google Scholar
Kruijer, T. S., Kleine, T., Fischer-Godde, M. & Sprung, P. 2015. Lunar tungsten isotopic evidence for the late veneer. Nature 520, 534–7.Google Scholar
Marks, N. E., Borg, L. E., Hutcheon, I. D., Jacobsen, B. & Clayton, R. N. 2014. Samarium-neodymium chronology and rubidium-strontium systematics of an Allende calcium-aluminum-rich inclusion with implications for 146Sm half-life. Earth and Planetary Science Letters 405, 1524.Google Scholar
McLeod, C. L., Brandon, A. D. & Armytage, M. G. 2014. Constraints on the formation age and evolution of the Moon from 142Nd-143Nd systematics of Apollo 12 basalts. Earth and Planetary Science Letters 396, 179–89.Google Scholar
Meier, M. M. M., Reufer, A. & Weiler, R. 2014. On the origin and composition of Theia: constraints from new models of the giant impact. Icarus 242, 316–28.CrossRefGoogle Scholar
Murphy, D. T., Brandon, A. D., Debaille, V., Burgess, R. & Ballentine, C. 2010. In search of a hidden long-term isolated sub-chondritic 142Nd/144Nd reservoir in the deep mantle: implications for the Nd isotope systematics of the Earth. Geochimica Cosmochimica Acta 74, 738–50.Google Scholar
Nebel, O., van Westrenen, W., Vroon, P. Z., Wille, M. & Raith, M. M. 2010. Deep mantle storage of the Earth's missing niobium in late-stage residual melts from a magma ocean. Geochimica Cosmochimica Acta 74, 4392–404.CrossRefGoogle Scholar
Nyquist, L. E., Bogard, D. D., Shih, C.-Y., Greshake, A., Stöffler, D. & Eugster, O. 2001. Ages and geologic histories of Martian meteorites. Space Science Reviews 96, 105–64.CrossRefGoogle Scholar
Nyquist, L. E., Wiesmann, H., Bansal, B., Shih, C.-Y., Keith, J. E. & Harper, C.L. 1995. 146Sm–142Nd formation interval for the lunar mantle. Geochimica et Cosmochimica Acta 59, 2817–37.Google Scholar
O’Neill, H. St. C. & Palme, H. 2008. Collisional erosion and the non-chondritic composition of the terrestrial planets. Philosophical Transactions of the Royal Society A 366, 4205–38.Google Scholar
O’Nions, R. K., Evensen, N. M. & Hamilton, P. J. 1979. Geochemical modelling of mantle differentiation and crustal growth. Journal of Geophysical Research 84, 6091–101.Google Scholar
Qin, L., Carlson, R. W. & Alexander, C. M. O’D. 2011. Correlated nucleosynthetic isotopic variability in Cr, Sr, Ba, Sm, Nd and Hf in Murchison and QUE 97008. Geochimica et Cosmochimica Acta 75, 7806–28.Google Scholar
Ranen, M. C. & Jacobsen, S. B. 2006. Barium isotopes in chondritic meteorites: implications for planetary reservoir models. Science 314, 809–12.CrossRefGoogle ScholarPubMed
Sprung, P., Kleine, T. & Scherer, E. E. 2013. Isotopic evidence for chondritic Lu/Hf and Sm/Nd of the Moon. Earth and Planetary Science Letters 380, 7787.CrossRefGoogle Scholar
Taylor, D. J., McKeegan, K. D. & Harrison, T. M. 2009. Lu–Hf zircon evidence for rapid lunar differentiation. Earth and Planetary Science Letters 279, 157–64.Google Scholar
Tolstikhin, I. N. & Hofmann, A. W. 2005. Early crust on top of the Earth's core. Physics of the Earth and Planetary Interiors 148, 109–30.Google Scholar
Tolstikhin, I. N., Kramers, J. D. & Hofmann, A. W. 2006. A chemical Earth model with whole mantle convection: the importance of a core–mantle boundary layer (D″) and its early formation. Chemical Geology 226, 7999.CrossRefGoogle Scholar
Touboul, M., Puchtel, I. S. & Walker, R. J. 2015. Tungsten isotopic evidence for disproportional late accretion to the Earth and Moon. Nature 520, 530–3.Google Scholar
Trinquier, A., Birck, J.-L. & Allegre, C. J. 2007. Widespread 54Cr heterogeneity in the inner solar system. Astrophysical Journal 655, 1179–85.Google Scholar
Warren, P. H. 2008. A depleted, not ideally chondritic Bulk Earth: the explosive-volcanic basalt loss hypothesis. Geochimica et Cosmochimica Acta 72, 2217–35.Google Scholar
Wen, L., Silver, P., James, D. & Kuehnel, R. 2001. Seismic evidence for a thermo-chemical boundary at the base of the Earth's mantle. Earth and Planetary Science Letters 189, 141–53.Google Scholar
Wiechert, U., Halliday, A. N., Lee, D.-C., Snyder, G. A., Taylor, L. A. & Rumble, D. 2001. Oxygen isotopes and the Moon-forming giant impact. Science 294, 345–8.Google Scholar