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.

Rare meteorites common in the Ordovician period


Most meteorites that fall today are H and L type ordinary chondrites, yet the main belt asteroids best positioned to deliver meteorites are LL chondrites1,2. This suggests that the current meteorite flux is dominated by fragments from recent asteroid breakup events3,4 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 ago5. 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 options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Micrometeorite-bearing limestone beds at the Lynna River section in northwestern Russia that were deposited around 466 million years ago.
Figure 2: Values of Δ17O and TiO2 of our data compared with compositions of different relevant meteorite groups.
Figure 3: Probability density functions (PDFs) of Δ17O values showing the distribution of different micrometeorite categories.


  1. 1

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

    Article  ADS  Google Scholar 

  2. 2

    Dunn, T. L., Burbine, T. H., Bottke, W. F. Jr & Clark, J. P. Mineralogies and source regions of near-Earth asteroids. Icarus 222, 273–282 (2014).

    Article  ADS  Google Scholar 

  3. 3

    Nesvorný, D., Vokrouhlický, D., Morbidelli, A. & Bottke, W. F. Asteroidal source of L chondrite meteorites. Icarus 200, 698–701 (2009).

    Article  ADS  Google Scholar 

  4. 4

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

    Google Scholar 

  5. 5

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

    Article  ADS  Google Scholar 

  6. 6

    Schmitz, B., Häggström, T. & Tassinari, M. Sediment-dispersed extraterrestrial chromite traces a major asteroid disruption event. Science 300, 961–964 (2003).

    Article  ADS  Google Scholar 

  7. 7

    Heck, P. R. 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).

    Article  ADS  Google Scholar 

  8. 8

    Heck, P. R. 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).

    Article  ADS  Google Scholar 

  9. 9

    Heck, P. R., Schmitz, B., Baur, H., Halliday, A. N. & Wieler, R. Fast delivery of meteorites to Earth after a major asteroid collision. Nature 430, 323–325 (2004).

    Article  ADS  Google Scholar 

  10. 10

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

    Article  Google Scholar 

  11. 11

    Heck, P. R., Schmitz, B., Baur, H. & Wieler, R. 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).

    Article  ADS  Google Scholar 

  12. 12

    Alwmark, C., Schmitz, B., Meier, M. M. M., Baur, H. & Wieler, R. 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).

    Article  ADS  Google Scholar 

  13. 13

    Meier, M. M. M., Schmitz, B., Lindskog, A., Maden, C. & Wieler, R. Cosmic-ray exposure ages of fossil micrometeorites from mid-Ordovician sediments at Lynna River, Russia. Geochim. Cosmochim. Acta 125, 338–350 (2014).

    Article  ADS  Google Scholar 

  14. 14

    Van Ginneken, M., Folco, L., Cordier, C. & Rochette, P. Chondritic micrometeorites from the Transantarctic Mountains. Meteorit. Planet. Sci. 47, 228–247 (2012).

    Article  ADS  Google Scholar 

  15. 15

    Prasad, M. S., Rudraswami, N. G., De Araujo, A., Babu, E. V. S. S. K. & Kumar, T. V. Ordinary chondritic micrometeorites from the Indian Ocean. Meteorit. Planet. Sci. 50, 1013–1031 (2015).

    Article  ADS  Google Scholar 

  16. 16

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

    Article  ADS  Google Scholar 

  17. 17

    Clayton, R. N. & Mayeda, T. K. Oxygen isotope studies of achondrites. Geochim. Cosmochim. Acta 60, 1999–2017 (1996).

    Article  ADS  Google Scholar 

  18. 18

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

    Article  ADS  Google Scholar 

  19. 19

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

    Article  Google Scholar 

  20. 20

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

    Google Scholar 

  21. 21

    Swindle, T. D., Kring, D. A. & Weirich, J. R. 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).

    Google Scholar 

  22. 22

    Jourdan, F., Andreoli, M. A. G., McDonald, I. & Maier, W. D. 40Ar/39Ar thermochronology of the fossil LL6-chondrite from the Morokweng crater, South Africa. Geochim. Cosmochim. Acta 74, 1734–1747 (2010).

    Article  ADS  Google Scholar 

  23. 23

    Dykhuis, M. J., Molnar, L., Van Kooten, S. J. & Greenberg, R. Defining the Flora family: Orbital properties, reflectance properties and age. Icarus 243, 111–128 (2014).

    Article  ADS  Google Scholar 

  24. 24

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

    Article  ADS  Google Scholar 

  25. 25

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

    Article  ADS  Google Scholar 

  26. 26

    Cordier, C. 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).

    Article  ADS  Google Scholar 

  27. 27

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

    Article  ADS  Google Scholar 

  28. 28

    Kita, N. T., Ushikubo, T., Fu, B. & Valley, J. W. High precision SIMS oxygen isotope analysis and the effect of sample topography. Chem. Geol. 264, 43–57 (2009).

    Article  ADS  Google Scholar 

  29. 29

    Schmitz, B. & Häggström, T. 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).

    Article  ADS  Google Scholar 

  30. 30

    Bottke, W. F., Nesvorny, D., Grimm, E. R., Morbidelli, A. & O’Brien D. P. Iron meteorites as remnants of planetesimals formed in the terrestrial planet region. Nature 439, 821–824 (2006).

    Article  ADS  Google Scholar 

  31. 31

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

    ADS  Google Scholar 

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




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.

Corresponding author

Correspondence to Philipp R. Heck.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Figures 1 and 2, Supplementary Table 1, description of Supplementary Data files. (PDF 284 kb)

Supplementary Data 1

Data table with Δ17O, TiO2 and V2O3 values and classification of fossil micrometeorites. (XLSX 15 kb)

Supplementary Data 2

Chrome spinel abundances in different types of meteorites. (XLSX 46 kb)

Supplementary Data 3

Reference data. (XLSX 55 kb)

Supplementary Data 4

Full data table with O-isotopic SIMS data and quantitative elemental EDS data. (XLSX 19 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Heck, P., Schmitz, B., Bottke, W. et al. Rare meteorites common in the Ordovician period. Nat Astron 1, 0035 (2017).

Download citation

Further reading


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