Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning,China:New 40Ar÷39Ar dating of the Yixian and Tuchengzi Formations


We report new 40Ar÷39Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion 40Ar÷39Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion 40Ar÷39Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca÷K ratios, excellent reproducibility and gave a mean age of 125.0±0.18 (1SD)±0.04 (SE) Ma. Single sanidine crystal total fusion 40Ar÷39Ar analyses of the Hengdaozi tuff gave a mean age of 125.0±0.19 (1SD)±0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4±0.19 (1SD)±0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.

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  1. 1.

    Zhou, Z. H., Wang, X. L., Zhang, F. C. et al., Important features of Caudipteryx-evidence from two nearly complete new specimens, Vert. PalAsiat., 2000, 38(4): 241.

    Google Scholar 

  2. 2.

    Wang, X. L., Xu, X., A new iguanodontid (Jinzhousaurus yangi gen. et sp. nov.) from the Yixian Formation of western Liaoning, China, Chinese Sci. Bull., 2001, 46(19): 1669.

    Article  Google Scholar 

  3. 3.

    Zhang, F. C., Zhou, Z. H., A primitive enantiornithine bird and the origin of feathers, Science, 2000, 290: 1955.

    Article  Google Scholar 

  4. 4.

    Li, J. L., Wang, Y., Wang, Y. Q. et al., A new family of primitive mammal from the Mesozoic of western Liaoning, China, Chinese Sci. Bull., 2001, 46(9): 782.

    Article  Google Scholar 

  5. 5.

    Wang, D. F., On the age of the Rehe Group in western Liaoning Province, China, Bull. Chinese Acad. Geol. Sci., 1983, 7: 65.

    Google Scholar 

  6. 6.

    Wang, D. F., Diao, N. C., Geochronology of Jura-Cretaceous volcanics in west Liaoning, China, in Scientific Papers on Geology for International Exchange (1), Beijing: Geological Publishing House, 1984, 1–12.

    Google Scholar 

  7. 7.

    Swisher III, C. C. Wang, Y. Q., Wang, X. L. et al., Cretaceous Age for the feathered dinosaurs of Liaoning, China, Nature, 1999, 400, 58.

    Article  Google Scholar 

  8. 8.

    Smith, P. E., Evensen, N. M., York, D. et al., Dates and rates in ancient lakes: 40Ar-39Ar evidence for an Early Cretaceous age for the Jehol Group, Northeast China, Can. J. Earth Sci., 1995, 32, 1426.

    Google Scholar 

  9. 9.

    Wang, S. S., Wang, Y.Q., Hu, H. G. et al., The existing time of Sihetun vertebrate in western Liaoning-evidence from U-Ph dating of zircon, Chinese Sci. Bull., 2001, 46 (9): 779.

    Google Scholar 

  10. 10.

    Wang, S. S., Hu, H. G., Li, P. X. et al., Further discussion on geologic age of Sihetun vertebrate assemblage in western Liaoning, China:evidence from Ar-Ar dating, Act. Petrolog. Sin., 2001, 17(4): 663

    Google Scholar 

  11. 11.

    Lo, C. H., Chen, P. J., Tsou, T. Y. et al., Age of Sinosauropteryx and Confuciusornis-40Ar÷39Ar laser single-grain and K-Ar dating of the Yixian Formation, N.E. China, Geochemica, 1999, 28(4), 405.

    Google Scholar 

  12. 12.

    Lo, C. H., Chen, P. J., Tsou, T. Y. et al., 40Ar÷39Ar laser single-grain and K-Ar dating of the Yixian Formation, NE China, Palaeoworld, 1999(11):328.

  13. 13.

    Jiang, F. X., Chen, J. H., Cao, M. Z. et al., A discussion on the age of the feathered dinosaur-bearing beds of Liaoning, China, Acta Palaeont. Sin., 2000, 39(2): 307.

    Google Scholar 

  14. 14.

    Gradstein, F. M., Agterberg, F. P., Ogg, J. G. et al., A Triassic, Jurassic and Cretaceous times scale. In:Berggren, W. A., Kent, D. V., Aubry, M. P. et al., eds. Geochronology, Time Scales and Global Stratigraphic Correlation. S.E.P.M. Spec. Publ., 1999, 54:95.

  15. 15.

    Wang, X. L., Wang, Y. O., Wang, Y. et al., Stratigraphic sequence and vertebrate-bearing beds of the lower part of the Yixian Formation in Sihetun and neighboring area, western Liaoning, China, Vert. PalAsiat., 1998, 36(2): 81.

    Google Scholar 

  16. 16.

    Wang, X. L., Wang, Y. O., Jin, F. et al., The Sihetun fossil vertebrate assemblage and its geological setting, western Liaoning, China, Palaeoworld, 1999(11):310.

  17. 17.

    Renne, P. R., Swisher, C. C., Deino, A. L. et al., Intercalibration of standards, absolute ages and uncertainties in 40Ar÷39Ar dating, Chemical Geology, 1998, 145: 117.

    Article  Google Scholar 

  18. 18.

    McDougall, I., Harrison, T. M., Geochronology and Thermochronology, New York: Oxford University Press, 1988.

    Google Scholar 

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Swisher, C.C., Wang, X., Zhou, Z. et al. Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning,China:New 40Ar÷39Ar dating of the Yixian and Tuchengzi Formations. Chin.Sci.Bull. 47, 136–139 (2002). https://doi.org/10.1360/02tb9031

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  • 40Ar÷39Ar dating
  • Cretaceous
  • Yixian Formation
  • Tuchengzi Formation
  • western Liaoning