Abstract
RECENT use of tektites as evidence for a bolide impact at the Cretaceous/Tertiary (K/T) boundary has focused attention on their long-term stability1–5. It was proposed in these studies that residual clay features with the spherical tektite morphology result from in situ alteration of the original glassy material. By contrast, examination of tektite alteration as an analogue for the long-term degradation of nuclear waste glass has revealed no evidence of alteration, hydration or devitrification either for samples found in nature or for those reacted in the laboratory6–9: no residual clay minerals were observed, and therefore the glass was interpreted as having reacted by a complete dissolution or etching process10–12. Here we show that these apparently incongruent observations can be reconciled through understanding the relationship between the environment in which the glass reacts and the chemical processes that control the reaction rate. We have examined both natural and experimental alteration of tektites and have found that, under conditions of restricted water contact, tektite reaction is dominated by water diffusion and in situ hydrolysis of the glass structure, followed by restructuring of the silicate network to form clays. Over time, the effective rate for these processes is lower than that for etching. Thus alteration of tektites to clays, as observed at the K/T boundary, can proceed only under conditions of limited water contact.
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References
Montanari, A. et al. Geology 11, 668–671 (1983).
Sigurdsson, H. et al. Nature 349, 482–487 (1991).
Margolis, S., Claeys, P. & Kyte, F. Science 251, 1594–1597 (1991).
Kastner, M., Asaro, F., Alvarez, W. & Alvarez, L. J. non-cryst. Solids 67, 463–464 (1984).
Izett, G., Dalrymple, G. & Snee, L. Science 252, 1539–1542 (1991).
Barkatt, A. A. et al. Geochim. cosmochim. Acta 48, 361–371 (1984).
O'Keefe, J. Advances in Ceramics. Vol. 20, Nuclear Waste Management II, 689–692 (American Ceramic Society Inc., Westerville, 1986).
Glass, B. P. J. non-cryst. Solids 67, 333–344 (1984).
Lutze, W. & Ewing, R. (eds) Radioactive Waste Forms of the Future (North Holland, New York, 1988).
Ewing, R. C. Scientific Basis for Nuclear Waste Management I, 57–68 (Plenum, New York, 1979).
Berger, R. & Ericson, J. in Recent Advances in Science and Technology of Materials (ed. Bishay, A.) (Plenum, New York, 1974).
LaMarche, P. H., Rauch, F. & Lanford, W. A. J. non-cryst. Solids 67, 361–369 (1984).
Friedman, I. & Long, W. D. Science 191, 347–352 (1976).
Mazer, J. J., Stevenson, C. M., Ebert, W. L. & Bates, J. K. Am. Antiq. 56, 504–513 (1991).
Abrajano, T. A., Bates, J. K., Woodland, A. B., Bradley, J. P. & Bourcier, W. L. Clays Clay Miner. 38, 537–548 (1990).
Advocat, T., Crovisier, J., Vernaz, E., Ehret, G. & Charpentier, H. Mat. Res. Soc. Symp. Proc. Vol. 212, 57–64 (Pittsburgh, 1991).
Kring, D. A. & Boynton, W. V. Geochim. cosmochim. Acta 55, 1737–1742 (1991).
Jiang, X. & Peacor, D. Clays Clay Miner. 39, 1–13 (1991).
Brindley, G. W. & Brown, G. in Crystal Structures of Clay Minerals and their X-Ray Identification (Mineralogical Society, London, 1980).
Bornhold, B. D. & Giresse, P. J. sedim. Petrol. 55, 653–664 (1985).
Montanari, A. J. sedim. Petrol. 61, 315–339 (1991).
Bursill, L. A. J. Solid State Chem. 10, 72–94 (1974).
Banfield, J. F., Veblen, D. R. & Smith, D. J. Am. Miner. 76, 343–353 (1991).
Bates, J. K., Bradley, J. P. & Bourcier, W. L. High-Level Radioactive Waste Management: Proc. 2nd ann. int. Conf., Vol. 1, 720–727 (American Nuclear Society, La Grange Park, 1991).
Ebert, W. & Bates, J. K. Mat. Res. Soc. Symp. Proc. Vol. 176, 339–346 (Pittsburgh, 1990).
Friedman, I. & Smith, R. Am. Antiq. 25, 476–522 (1960).
Marshall, R. R. Geol. Soc. Am. Bull. 72, 1493–1520 (1961).
Lee, R. R., Leich, D. A., Tombrello, T. A., Ericson, J. E. & Friedman, I. Nature 250, 44–47 (1974).
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Mazer, J., Bates, J., Bradley, J. et al. Alteration of tektite to form weathering products. Nature 357, 573–576 (1992). https://doi.org/10.1038/357573a0
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DOI: https://doi.org/10.1038/357573a0
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