Lunar meteorite LaPaz 04841: Petrology, texture,
and impact-shock effects of a low-Ti mare
basalt
Found during the 2004 U.S. Antarctic Search for Meteorites season, LAP 04841 represents an addition to the LaPaz lunar basalts suite, and brings the total mass collected to 1.93 kg. Mineral modes and chemistries, as well as trace-element patterns, provide evidence for pairing of this meteorite to others in the suite. Analyses of chromite grains provide a V/(Al+Cr) ratio of 1.33 ± 13, translating to an fO2 one log unit below the IW buffer, in accordance with previous fO2 estimates. Pyroxene and olivine Mn/Fe values plot along the trend set for lunar basalts. The presence of FeNi grains, troilite, and the anorthositic composition of plagioclase are further evidence for the lunar origin of this meteorite. Application of the Zr-cooling speedometer, for ilmenite and ulvöspinel pairs, give a cooling rate of 5.2°C/day. Study of the impact-shock deformation of LAP 04841 reveals a considerable range of impact stress may be encountered within a few millimeters, suggesting complex controls on pressure dissipation throughout the meteorite.
Hill et al. (2008) Meteorit. Planet. Sci., submitted.
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Last revised: 12-2007