Publication Date:
2011-08-19
Description:
The Apollo 16 regolith breccias were characterized in terms of petrography, grain-size distribution, porosity, major and trace element composition, noble gas contents, and ferromagnetic resonance properties. Significant variation was found with respect to density and porosity; the more dense breccias displayed substantial shock damage. The breccias resembled the soils in grain-size distribution and in petrological components, though many were found to be compositionally different from the Apollo 16 soils in that a mafic component was lacking. Nearly all breccias showed evidence of irradiation at the lunar surface, and analyses of disaggregated breccias indicated that this irradiation occurred before compaction. The concentration of surface irradiation parameters were far less than those of lunar soils or breccias of other Apollo missions. Observations with respect to the argon isotope ratio and Xe presence have led to the possibility that breccia-surface irradiation occurred as early as four billion years ago, and that most Apollo 16 regolith breccias were not formed from any known Apollo 16 soil.
Keywords:
LUNAR AND PLANETARY EXPLORATION
Type:
Journal of Geophysical Research (ISSN 0148-0227); 91; D277-D30
Format:
text
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