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Science 12 October 1973:
Vol. 182. no. 4108, pp. 158 - 161
DOI: 10.1126/science.182.4108.158
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Articles

The 25-km Discontinuity: Implications for Lunar History

Gene Simmons 1, Terry Todd 1, and Herbert Wang 2

1 Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge 02139
2 Department of Geology and Geophysics, University of Wisconsin, Madison 53706

The lunar velocity profile and laboratory data on terrestrial and lunar rocks are constraints on models of lunar history. They show that shock-induced microcracks are absent from the rocks present in the moon today at depths of 25 to 60 kilometers. All possible causes of this observation are examined, and the most likely explanations are that either the rocks at depths of 25 to 60 kilometers formed after the major impacts ceased or the microcracks have annealed at temperatures of about 600°C over geologically long times.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Constitution and Structure of the Lunar Interior.
M. A. Wieczorek, B. L. Jolliff, A. Khan, M. E. Pritchard, B. P. Weiss, J. G. Williams, L. L. Hood, K. Righter, C. R. Neal, C. K. Shearer, et al. (2006)
Reviews in Mineralogy and Geochemistry 60, 221-364
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Science. ISSN 0036-8075 (print), 1095-9203 (online)