CaltechAUTHORS
  A Caltech Library Service

The equation of state of a lunar anorthosite: 60025

Jeanloz, Raymond and Ahrens, Thomas J. (1978) The equation of state of a lunar anorthosite: 60025. In: 9th Lunar and Planetary Science Conference. Geochimica et cosmochimica acta. Supplement. Vol.2. No.10. Pergamon Press , New York, NY, pp. 2789-2803. https://resolver.caltech.edu/CaltechAUTHORS:20150903-074125515

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20150903-074125515

Abstract

New, shock-wave, equation-of-state measurements of lunar anorthosite 60025 (-18% initial porosity) and single crystal anorthite in the 40 to 120 GPa (0.4-1.2 Mbar) pressure range are presented and compared, along with previous results on nonporous anorthosite and lunar samples. The porous lunar anorthosite exhibits a lower shock impedance than nonporous anorthosite which, in turn, has a lower impedance than either nonporous gabbroic anorthosite (15418) or high-titanium, mare basalt (70215). This suggests that crater statistics (and, hence, apparent cratering ages) for different lunar terranes are biased by the properties of the different target rocks: for a given set of impacts, systematically smaller craters will tend to be formed in (nonporous) high-Ti mare basalt, gabbroic anorthosite and anorthosite, respectively. The effect of initial porosity in anorthosite 60025 is significant: for a given impact, peak stresses are distinctly lower in the porous anorthosite (typically by about 20% in the 40-100 GPa range) than in the nonporous equivalent, whereas both shock and post-shock temperatures are considerably higher. For example, shock temperatures (at a given pressure) differ by about 10^3 to 4 X 10^3 Kover the range 40-100 GPa. Thus, maturing of a planetary surface by repeated impact (resulting in even mild brecciation and, hence, porosity) strongly enhances the thermal energy partitioning into the planet during meteoritic bombardment. The coupling of kinetic energy on impact is, however, decreased leading to a decrease in cratering efficiency due to increased porosity. These results imply that, as a result of successive impact events, the dynamic properties of a given rock unit as well as the entire planetary surface will evolve such that the efficiency in the trapping of thermal energy associated with impact will tend to increase with time.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
http://adsabs.harvard.edu/full/1978LPSC....9.2789JADSArticle
Additional Information:© 1978 Lunar and Planetary Institute. We thank E. Gelle and R. Smith for their dedicated assistance with the experiments, and Dr. Y. Syono for providing samples of anorthite. We also appreciate the helpful comments of Malcolm Somerville and James Long. The critical reviews of Rex V. Gibbons and Jon F. Bauer also improved the paper. This work was supported by NASA Grant NSG 9019. Contribution No. 3065, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125.
Funders:
Funding AgencyGrant Number
NASANSG 9019
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences 3065
Series Name:Geochimica et cosmochimica acta. Supplement
Issue or Number:10
Record Number:CaltechAUTHORS:20150903-074125515
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150903-074125515
Official Citation:The equation of state of a lunar anorthosite - 60025 Jeanloz, R. & Ahrens, T. J. In: Lunar and Planetary Science Conference, 9th, Houston, Tex., March 13-17, 1978, Proceedings. Volume 2. (A79-39176 16-91) New York, Pergamon Press, Inc., 1978, p. 2789-2803.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60040
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:11 Sep 2015 17:53
Last Modified:03 Oct 2019 08:53

Repository Staff Only: item control page