Most meteorites that fall today are H and L type ordinary chondrites, yet the main belt asteroids best positioned to deliver meteorites are LL chondrites 1,2 . This suggests that the current meteorite flux is dominated by fragments from recent asteroid breakup events 3,4 and therefore is not representative over longer (100-Myr) timescales. Here we present the first reconstruction of the composition of the background meteorite flux to Earth on such timescales. From limestone that formed about one million years before the breakup of the L-chondrite parent body 466 Myr ago, we have recovered relict minerals from coarse micrometeorites. By elemental and oxygen-isotopic analyses, we show that before 466 Myr ago, achondrites from different asteroidal sources had similar or higher abundances than ordinary chondrites. The primitive achondrites, such as lodranites and acapulcoites, together with related ungrouped achondrites, made up ~15–34% of the flux compared with only ~0.45% today. Another group of abundant achondrites may be linked to a 500-km cratering event on (4) Vesta that filled the inner main belt with basaltic fragments a billion years ago 5 . Our data show that the meteorite flux has varied over geological time as asteroid disruptions create new fragment populations that then slowly fade away from collisional and dynamical evolution. The current flux favours disruption events that are larger, younger and/or highly efficient at delivering material to Earth.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    et al. Compositional differences between meteorites and near-Earth asteroids. Nature 454, 858–860 (2008).

  2. 2.

    , , & Mineralogies and source regions of near-Earth asteroids. Icarus 222, 273–282 (2014).

  3. 3.

    , , & Asteroidal source of L chondrite meteorites. Icarus 200, 698–701 (2009).

  4. 4.

    et al. in Asteroids IV (eds Michel, P. et al. ) 701–724 (Univ. Arizona Press, 2015).

  5. 5.

    et al. High-velocity collisions from the lunar cataclysm recorded in asteroidal meteorites. Nat. Geosci. 6, 303–307 (2013).

  6. 6.

    , & Sediment-dispersed extraterrestrial chromite traces a major asteroid disruption event. Science 300, 961–964 (2003).

  7. 7.

    et al. A search for H-chondritic chromite grains in sediments that formed immediately after the breakup of the L-chondrite parent body 470 Ma ago. Geochim. Cosmochim. Acta 177, 120–129 (2016).

  8. 8.

    et al. A single asteroidal source for extraterrestrial Ordovician chromite grains from Sweden and China: High-precision oxygen three-isotope SIMS analysis. Geochim. Cosmochim. Acta 74, 497–509 (2010).

  9. 9.

    , , , & Fast delivery of meteorites to Earth after a major asteroid collision. Nature 430, 323–325 (2004).

  10. 10.

    Extraterrestrial spinels and the astronomical perspective on Earth’s geological record and evolution of life. Chem. Erde 73, 117–145 (2013).

  11. 11.

    , , & Noble gases in fossil micrometeorites and meteorites from 470 Myr old sediments from southern Sweden, and new evidence for the L-chondrite parent body breakup event. Meteorit. Planet. Sci. 43, 517–528 (2008).

  12. 12.

    , , , & A global rain of micrometeorites following breakup of the L-chondrite parent body: Evidence from solar wind-implanted Ne in fossil extraterrestrial chromite grains from China. Meteorit. Planet. Sci. 47, 1297–1304 (2012).

  13. 13.

    , , , & Cosmic-ray exposure ages of fossil micrometeorites from mid-Ordovician sediments at Lynna River, Russia. Geochim. Cosmochim. Acta 125, 338–350 (2014).

  14. 14.

    , , & Chondritic micrometeorites from the Transantarctic Mountains. Meteorit. Planet. Sci. 47, 228–247 (2012).

  15. 15.

    , , , & Ordinary chondritic micrometeorites from the Indian Ocean. Meteorit. Planet. Sci. 50, 1013–1031 (2015).

  16. 16.

    et al. Mineralogy of the Bocaiuva iron meteorite: A preliminary study. Meteoritics 20, 113–124 (1985).

  17. 17.

    & Oxygen isotope studies of achondrites. Geochim. Cosmochim. Acta 60, 1999–2017 (1996).

  18. 18.

    et al. A new type of solar-system material recovered from Ordovician marine limestone. Nat. Commun. 7, 11851 (2016).

  19. 19.

    Asteroid (4) Vesta: I. The howardite–eucrite–diogenite (HED) clan of meteorites. Chem. Erde 75, 155–183 (2015).

  20. 20.

    K–Ar ages of meteorites: Clues to parent-body thermal histories. Chem. Erde 71, 207–226 (2011).

  21. 21.

    , & in Advances in 40 Ar/ 39 Ar Dating: From Archaeology to Planetary Sciences Vol. 378 (eds Jourdan, F., Mark, D. F. & Verati, C. ) 333–347 (2014).

  22. 22.

    , , & 40Ar/39Ar thermochronology of the fossil LL6-chondrite from the Morokweng crater, South Africa. Geochim. Cosmochim. Acta 74, 1734–1747 (2010).

  23. 23.

    , , & Defining the Flora family: Orbital properties, reflectance properties and age. Icarus 243, 111–128 (2014).

  24. 24.

    & Oxygen isotopes in cosmic spherules and the composition of the near Earth interplanetary dust complex. Geochim. Cosmochim. Acta 146, 18–26 (2014).

  25. 25.

    et al. Ordinary chondrite-related giant (>800 μm) cosmic spherules from the Transantarctic Mountains, Antarctica. Geochim. Cosmochim. Acta 75, 6200–6210 (2011).

  26. 26.

    et al. HED-like cosmic spherules from the Transantarctic Mountains, Antarctica: Major and trace element abundances and oxygen isotopic compositions. Geochim. Cosmochim. Acta 77, 515–529 (2012).

  27. 27.

    , , & A Russian record of a Middle Ordovician meteorite shower: Extraterrestrial chromite at Lynna River, St. Petersburg region. Meteorit. Planet. Sci. 47, 1274–1290 (2012).

  28. 28.

    , , & High precision SIMS oxygen isotope analysis and the effect of sample topography. Chem. Geol. 264, 43–57 (2009).

  29. 29.

    & Extraterrestrial chromite in Middle Ordovician marine limestone at Kinnekulle, southern Sweden — traces of a major asteroid breakup event. Meteorit. Planet. Sci. 41, 455–466 (2006).

  30. 30.

    , , , & Iron meteorites as remnants of planetesimals formed in the terrestrial planet region. Nature 439, 821–824 (2006).

  31. 31.

    et al. NWA 5363/NWA 5400 and the Earth: Isotopic twins or just distant cousins? Lun. Planet. Inst. 46, 2732 (2015).

Download references


The study was supported by an ERC-Advanced Grant (ASTROGEOBIOSPHERE) to B.S. P.R.H. acknowledges funding from the Tawani Foundation. A.D. acknowledges support from the Russian Governmental Program of Competitive Growth of Kazan Federal University and RFBR (grant 16-05-00799). W.F.B’s participation was supported by NASA’s SSERVI program “Institute for the Science of Exploration Targets (ISET)” through institute grant number NNA14AB03A. We thank K. Deppert and P. Eriksson for support at Lund University, F. Iqbal for the laboratory work, and B. Strack for maintenance of the Field Museum’s SEM laboratory. WiscSIMS is partly supported by the National Science Foundation (EAR03-19230, EAR13-55590). We thank J. Kern for SIMS support. The 3D microscopy was performed in the Keck-II facility of the Northwestern University NUANCE Center, supported by NSEC (NSF EEC–0647560), MRSEC (NSF DMR-1121262), the Keck Foundation, the State of Illinois and Northwestern University.

Author information


  1. Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, Illinois 60605, USA

    • Philipp R. Heck
    • , Birger Schmitz
    •  & Surya S. Rout
  2. Chicago Center for Cosmochemistry and Department of the Geophysical Sciences, The University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, USA

    • Philipp R. Heck
    •  & Surya S. Rout
  3. Astrogeobiology Laboratory, Department of Physics, Lund University, PO Box 118, SE-22100 Lund, Sweden

    • Birger Schmitz
    • , Anders Cronholm
    •  & Fredrik Terfelt
  4. Department of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, Colorado 80302, USA

    • William F. Bottke
  5. WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton Street, Madison, Wisconsin 53706-1692, USA

    • Noriko T. Kita
    •  & Céline Defouilloy
  6. Geological Institute, Russian Academy of Sciences, Pyzhevsky Pereulok 7, 119017 Moscow, Russia

    • Andrei Dronov
  7. Kazan (Volga Region) Federal University, Kremlevskaya ulitsa 18, 420008 Kazan, Russia

    • Andrei Dronov


  1. Search for Philipp R. Heck in:

  2. Search for Birger Schmitz in:

  3. Search for William F. Bottke in:

  4. Search for Surya S. Rout in:

  5. Search for Noriko T. Kita in:

  6. Search for Anders Cronholm in:

  7. Search for Céline Defouilloy in:

  8. Search for Andrei Dronov in:

  9. Search for Fredrik Terfelt in:


P.R.H. and B.S. conceived the study and wrote the paper with input from all authors. W.F.B. provided expertise on the collisional and dynamical evolution of the asteroid belt and meteoroid delivery models. B.S., F.T. and A.D. conducted the fieldwork. B.S., F.T. and A.C. extracted and prepared the samples for SEM/EDS and SIMS. A.C. performed the quantitative SEM/EDS analysis. P.R.H. and S.S.R. prepared the samples for SIMS and performed the SIMS and post-SIMS analyses. N.T.K. and C.D. set up SIMS analysis conditions and assisted with the analyses.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Philipp R. Heck.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    Supplementary Figures 1 and 2, Supplementary Table 1, description of Supplementary Data files.

Excel files

  1. 1.

    Supplementary Data 1

    Data table with Δ17O, TiO2 and V2O3 values and classification of fossil micrometeorites.

  2. 2.

    Supplementary Data 2

    Chrome spinel abundances in different types of meteorites.

  3. 3.

    Supplementary Data 3

    Reference data.

  4. 4.

    Supplementary Data 4

    Full data table with O-isotopic SIMS data and quantitative elemental EDS data.

About this article

Publication history






Further reading