Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Prolonged KREEP magmatism on the Moon indicated by the youngest dated lunar igneous rock


Primordial solidification of the Moon (or its uppermost layer) resulted in the formation of a variety of rock types that subsequently melted and mixed to produce the compositional diversity observed in the lunar sample suite1,2. The initial rocks to crystallize from this Moon-wide molten layer (the magma ocean) contained olivine and pyroxene and were compositionally less evolved than the plagioclase-rich rocks that followed. The last stage of crystallization, representing the last few per cent of the magma ocean, produced materials that are strongly enriched in incompatible elements including potassium (K), the rare earth elements (REE) and phosphorus (P)—termed KREEP3,4,5. The decay of radioactive elements in KREEP, such as uranium and thorium, is generally thought to provide the thermal energy necessary for more recent lunar magmatism4,6,7. The ages of KREEP-rich samples are, however, confined to the earliest periods of lunar magmatism between 3.8 and 4.6 billion years (Gyr) ago8,9, providing no physical evidence that KREEP is directly involved in more recent lunar magmatism. But here we present evidence that KREEP magmatism extended for an additional 1 Gyr, based on analyses of the youngest dated lunar sample.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1
Figure 2: Age versus initial ɛNd plot for KREEP-rich lunar rocks (Mg and alkali-suites, and KREEP basalts) demonstrating that NWA 773 is derived from the most evolved (LREE-enriched) lunar source region yet known.
Figure 3: Plot of age versus Rb/Sr ratios of sample source regions calculated from their initial Sr isotopic compositions using a single-stage growth model.


  1. Wood, J. A., Dickey, J. S., Marvin, U. B. & Powell, B. N. Lunar anorthosites and a geophysical model of the Moon. Proc. 1st Lunar Planet. Sci. Conf. 965–988 (Pergamon, New York, 1970)

    Google Scholar 

  2. Smith, J. A., et al. Petrologic history of the Moon inferred from petrography, mineralogy, and petrogenesis of Apollo 11 rocks. Proc. 1st Lunar Planet. Sci. Conf. 1149–1162 (Pergamon, New York, 1970)

    Google Scholar 

  3. Snyder, G. A., Taylor, L. A. & Neal, C. R. A chemical model for generating the sources of mare basalts: Combined equilibrium and fractional crystallization of the lunar magmasphere. Geochim. Cosmochim. Acta 56, 3809–3823 (1992)

    ADS  CAS  Article  Google Scholar 

  4. Warren, P. H. & Wasson, J. T. The origin of KREEP. Rev. Geophys. Space Phys. 17, 73–88 (1979)

    ADS  CAS  Article  Google Scholar 

  5. Warren, P. H. The origin of pristine KREEP: Effects of mixing between urKREEP and the magmas parental to the Mg-rich cumulates. Proc. 8th Lunar Planet. Sci. Conf. 233–241 (1988)

    Google Scholar 

  6. Hess, P. C. & Parmentier, E. M. Thermal evolution of a thicker KREEP liquid layer. J. Geophys. Res. 106, 28023–28032 (2001)

    ADS  CAS  Article  Google Scholar 

  7. Wieczorek, M. A. & Phillips, R. J. The “Procellarum KREEP Terrane”: Implications for mare volcanism and lunar evolution. J. Geophys. Res. 105, 20417–20430 (2000)

    ADS  CAS  Article  Google Scholar 

  8. Nyquist, L. E. & Shih, C.-Y. The isotopic record of lunar volcanism. Geochim. Cosmochim. Acta 56, 2213–2234 (1992)

    ADS  CAS  Article  Google Scholar 

  9. Snyder, G. A., Borg, L. E., Nyquist, L. E. & Taylor, L. A. in Chronology and Isotopic Constraints on Lunar Evolution (eds Canup, R. & Righter, K.) 361–395 (Univ. Ariz. Press, Tucson, 2000)

    Google Scholar 

  10. Fagan, T. J. et al. Northwest Africa 773: Lunar origin and iron-enrichment trend. Meteorit. Planet. Sci. 38, 529–554 (2003)

    ADS  CAS  Article  Google Scholar 

  11. Jolliff, B. L., Korotev, R. L., Zeigler, R. A. & Floss, C. Northwest Africa 773: Lunar mare breccia with a shallow-formed olivine-cumulate component, very low Ti (VLT) heritage and a KREEP connection. Geochim. Cosmochim. Acta 67, 4857–4879 (2003)

    ADS  CAS  Article  Google Scholar 

  12. Borg, L. E., Nyquist, L. E., Weismann, H., Shih, C.-Y. & Reese, Y. The age of Dar al Gani 476 and the differentiation history of the martian meteorites inferred from their radiogenic isotopic systematics. Geochim. Cosmochim. Acta 67, 3519–3536 (2003)

    ADS  CAS  Article  Google Scholar 

  13. Ludwig, K. J. R. Users Manual for Isoplot/Ex v. 2.49: A Geochronological Toolkit for Microsoft Excel (Berkeley Geochronology Center Special Publication No. 1a, BGC, Berkeley, 2001) 〈

    Google Scholar 

  14. Fernandes, V. A., Burges, R. & Turner, G. 40Ar-39Ar chronology of lunar meteorites Northwest Africa 032 and 773. Meteorit. Planet. Sci. 38, 555–564 (2003)

    ADS  CAS  Article  Google Scholar 

  15. Hiesinger, H., Head, J. W., Wolf, U., Jaumann, R. & Neukum, G. Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Nubium, Mare Cognitum, and Mare Insularum. J. Geophys. Res. 108, 1–27 (2003)

    Article  Google Scholar 

  16. Nyquist, L. E., Bansal, B. M., Wooden, J. L. & Wiesmann, H. Sr-isotopic constraints on the petrogenesis of Apollo 12 basalts. Proc. 8th Lunar Planet. Sci. Conf. 1383–1415 (Pergamon, New York, 1977)

    Google Scholar 

  17. Papanastassiou, D. A. & Wasserburg, G. J. Rb-Sr age of troctolite 76535. Proc. 7th Lunar Sci. Conf. 2035–2054 (Pergamon, New York, 1976)

    Google Scholar 

  18. Shih, C.-Y. et al. Age of pristine noritic clasts from lunar breccias 15445 and 15455. Geochim. Cosmochim. Acta 57, 915–931 (1993)

    ADS  CAS  Article  Google Scholar 

  19. Warren, P. H. in Workshop on Moon in Transition: Apollo 14, KREEP, and Evolved Lunar Rocks 149–153 (LPI Technical Report 98–03, Lunar and Planetary Institute, Houston, 1989)

    Google Scholar 

  20. Shih, C.-Y., Nyquist, L. E., Bansal, B. M. & Weismann, H. Rb-Sr and Sm-Nd chronology of an Apollo 17 KREEP basalt. Earth Planet. Sci. Lett. 108, 203–215 (1992)

    ADS  CAS  Article  Google Scholar 

  21. Hughes, S. S., Delano, J. W. & Schmitt, R. A. Apollo 15 yellow-brown glass: Chemistry and petrogenetic relations to green volcanic glass and olivine-normative basalts. Geochim. Cosmochim. Acta 52, 2379–2391 (1988)

    ADS  CAS  Article  Google Scholar 

  22. Snyder, G. A., Taylor, L. A. & Halliday, A. N. Chronology and petrogenesis of the lunar highlands alkali suite: Cumulates from KREEP basalt crystallization. Geochim. Cosmochim. Acta 59, 1185–1203 (1995)

    ADS  CAS  Article  Google Scholar 

  23. Snyder, G. A., Neal, C. R., Taylor, L. A. & Halliday, A. N. Processes involved in the formation of magnesian-suite plutonic rocks from the highlands of the Earth's moon. J. Geophys. Res. 100, 9365–9388 (1995)

    ADS  CAS  Article  Google Scholar 

  24. Dash, E. J. et al. Time of crystallization of a unique A15 basalt. Lunar Planet. Sci. Conf. XX, 218–219 (1989)

    ADS  Google Scholar 

Download references


We thank L. Nyquist for the use of his heavy liquid separations facility at the Johnson Space Center, M. Grady and S. Russell of the Natural History Museum, London for providing us with the sample, and two anonymous reviewers for their comments. This work was supported by NASA Cosmochemistry Program.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Lars E. Borg.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Borg, L., Shearer, C., Asmerom, Y. et al. Prolonged KREEP magmatism on the Moon indicated by the youngest dated lunar igneous rock. Nature 432, 209–211 (2004).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing