Skip to main content


Mn−Cr ages of Fe-rich olivine in two Rumuruti (R) chondrites

Article metrics

  • 241 Accesses

  • 5 Citations


Mn−Cr systematics in olivine of two Rumuruti (R) chondrites was investigated. Mn/52Cr ratios up to 1800 and 1300, and δ53Cr of up to 25‰ and 7‰ were observed for NWA 753 and Sahara 99531, respectively. All data points of NWA 753 show a linear correlation between δ53Cr values and Mn/52Cr ratios on the isochron diagram. The inferred initial 53Mn/55Mn ratio for NWA 753 is (1.84 ± 0.42(2σ)) × 10−6. In the case of Sahara 99531, a positive correlation interpreted as an isochron for 53Mn/55Mn = 2.75 ± 1.55(2σ) × 10−6 was obtained for only one chondrule. Data from other chondrules in Sahara 99531 give an upper limit of 53Mn/55Mn = 0.49 × 10−6. The Mn−Cr ages of NWA 753 and a chondrule in Sahara 99531 are slightly older than that of the angrite LEW 86010 (Lugmair and Shukolyukov, 1998). Other chondrules in Sahara 99531 are at least 5 Ma younger than the LEW 86010. The Mn-Cr ages of olivine in R chondrites correspond to the time when olivine became a closed system either during slow cooling from the peak metamorphic temperature or during rapid cooling by impact excavation. In either case the olivine closure occurred earlier than the final assembly of the brecciated chondrites.


  1. Amelin, Y., A. N. Krot, I. D. Hutcheon, and A. A. Ulyanov, Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions, Science, 297, 1678–1683, 2002.

  2. Baker, J., M. Bizzaro, N. Wittig, J. Connelly, and H. Haack, Early planetesimal melting from an age of 4.5562 Gyr for differentiated meteorites, Nature, 436, 1127–1131, 2005.

  3. Bischoff, A., Mineral characterization of primitive, type −3 lithologies in Rumuruti chondrites, Meteoritics & Planet. Sci., 35, 699–706, 2000.

  4. Bischoff, A., T. Geiger, H. Palme, B. Spettel, L. Schultz, P. Scherer, T. Loeken, P. Bland, R. N. Clayton, T. K. Mayeda, U. Herpers, B. Meltzow, R. Michel, and B. Dittrich-Hannen, Acfer 217—A new member of the Rumuruti chondrite group (R), Meteoritics, 29, 264–274, 1994.

  5. Bischoff, A. and G. Srinivasan, Mg-26 excess in hibonites of the Rumuruti chondrite Hughes 030, Meteorotics & Planetary Sci., 38, 5–12, 2003.

  6. Dixon, E. T., D. D. Bogard, and D. H. Garrison, 39Ar-40Ar chronology of R chondrites, Meteoritics & Planetary Sci., 38, 341–355, 2003.

  7. Ebisawa, N., J. Park, and K. Nagao, Noble gases in Northwest Africa 753 (NWA 753), Rumuruti chondrites, Geochim. Cosmochim. Acta, 67(A84), 2003.

  8. Greenwood, J. P., A. E. Rubin, and J. T. Wasson, Oxygen isotopes in R-chondrite magnetite and olivine: Links between R chondrites and ordinary chondrites, Geochim. Cosmochim. Acta, 64, 3897–3911, 2000.

  9. Grossman, J. N. and A. J. Brearley, The onset of metamorphism in ordinary and carbonaceous chondrites, Meteoritics & Planetary Sci., 40, 87–122, 2005.

  10. Hsu, W., Mn−Cr systematics of pallasites, Geochem. J., 39, 311–316, 2005.

  11. Hua, X., G. R. Huss, S. Tachibana, and T. G. Sharp, Oxygen, silicon, and Mn−Cr isotopes of fayalite in the Kaba oxidized CV3 chondrite: Constraints for its formation history, Geochim. Cosmochim. Acta, 1333–1348, 2005.

  12. Ito, M. and J. Ganguly, Diffusion kinetics of Cr in olivine and 53Mn−53Cr thermo-chronology of early solar system objects, Geochim. Cosmochim. Acta, 70, 799–809, 2006.

  13. Kallemeyn, G.W., A. E. Rubin, and J. T. Wasson, The compositional classification of chondrites 7. The R chondrite group, Geochim. Cosmochim Acta, 60, 2243–2256, 1996.

  14. Kita, N., H. Nagahara, S. Togashi, and Y. Morishita, A short duration of chondrule formation in the solar nebula: Evidence from 26Al in Semarkona ferromagnesian chondrules, Geochim. Cosmochim. Acta, 64, 3913–3922, 2000.

  15. Krot, A. N., A. J. Brearley, M. Petaev, G. W. Kallemeyn, D. W. G. Sears, P. Benoit, I. D. Hutcheon, M. E. Zolensky, and K. Keil, Evidence for low temperature growth of fayalite and hedenbergite in MacAlpine Hills 88107, an ungrouped carbonaceous chondrites related to the CM-CO clan, Meteoritics & Planetary Sci., 35, 1365–1386, 2000.

  16. Lugmair, G.W. and A. Shukolyukov, Early solar system timescales according to 53Mn−53Cr systematics, Geochim. Cosmochim. Acta, 62, 2863–2886, 1998.

  17. Nakagawa, Y., C. Hayashi, and K. Nakazawa, Accumulation of planetesimals in the solar nebula, Icarus, 54, 361–376, 1983.

  18. Nyquist, L., L. Lindstrom, D. Mittlefehldt, C.-Y. Shih, H. Weismann, S. Wentworth, and R. Martinez, Manganese-chromium formation intervals for chondrules from the Bishumpur and Chainpur meteorites, Meteoritics & Planetary Sci., 36, 911–938, 2001.

  19. Rubin, A. and G. W. Kallemeyn, Pecora Escarpment 91002: A member of the new Rumuruti (R) chondrite group, Meteoritics, 29, 255–264, 1994.

  20. Schultz, L. and H. W. Weber, The irradiation history of Rumurutichondrites, 26th Symp. Ant. Met. p.128, 2001.

  21. Schultz, L., H. W. Weber, and L. Franke, Rumuruti chondrites: Noble gases, exposure ages, pairing, and parent body history, Meteoritics & Planetary Sci., 40, 557–571, 2005.

  22. Schulze, H., A. Bischoff, H. Palme, B. Spettel, D. Dreibus, and J. Otto, Mineralogy and chemistry of Rumuruti: The first meteorite fall of the new R chondrite group, Meteoritics, 29, 275–286, 1994.

  23. Sugiura, N. and H. Hoshino, Mn−Cr chronology of five IIIAB iron meteorites, Meteoritics & Planet. Sci., 38, 117–144, 2003.

  24. Sugiura, N., A. Miyazaki, and K. Yanai, Widespread magmatic activities on the angrite parent body at 4562 Ma ago, Earth Planets Space, 57, e13–e16, 2005.

  25. Turner, G., M. C. Enright, and P. H. Cadogan, The early history of chondrites parent bodies inferred from 40Ar-39Ar ages, Proc. 9th Lunar Planet. Sci. Conf., pp. 989–1025, 1978.

  26. Weisberg, M. K., M. Prinz, H. Kojima, K. Yanai, R. N. Clayton, and T. K. Mayeda, The Carlisle Lakes-type chondrites: A new grouplet with high δ17O and evidence for nebula oxidation, Geochim. Cosmochim. Acta, 55, 2657–2669, 1991.

  27. Yomogida, K. and T. Matsui, Physical-properties of ordinary chondrites, J. Geophys. Res., 88, 9513–9533, 1983.

Download references

Author information

Correspondence to Naoji Sugiura.

Rights and permissions

Reprints and Permissions

About this article

Key words

  • Age
  • chondrites
  • olivine
  • Mn
  • Cr