TY - JOUR
T1 - Coesite and stishovite in a shocked lunar meteorite, Asuka-881757, and impact events in lunar surface.
AU - Ohtani, E.
AU - Ozawa, S.
AU - Miyahara, M.
AU - Ito, Y.
AU - Mikouchi, T.
AU - Kimura, M.
AU - Arai, T.
AU - Sato, K.
AU - Hiraga, K.
PY - 2011/1/11
Y1 - 2011/1/11
N2 - Microcrystals of coesite and stishovite were discovered as inclusions in amorphous silica grains in shocked melt pockets of a lunar meteorite Asuka-881757 by micro-Raman spectrometry, scanning electron microscopy, electron back-scatter diffraction, and transmission electron microscopy. These high-pressure polymorphs of SiO(2) in amorphous silica indicate that the meteorite experienced an equilibrium shock-pressure of at least 8-30 GPa. Secondary quartz grains are also observed in separate amorphous silica grains in the meteorite. The estimated age reported by the (39)Ar/(40)Ar chronology indicates that the source basalt of this meteorite was impacted at 3,800 Ma ago, time of lunar cataclysm; i.e., the heavy bombardment in the lunar surface. Observation of coesite and stishovite formed in the lunar breccias suggests that high-pressure impact metamorphism and formation of high-pressure minerals are common phenomena in brecciated lunar surface altered by the heavy meteoritic bombardment.
AB - Microcrystals of coesite and stishovite were discovered as inclusions in amorphous silica grains in shocked melt pockets of a lunar meteorite Asuka-881757 by micro-Raman spectrometry, scanning electron microscopy, electron back-scatter diffraction, and transmission electron microscopy. These high-pressure polymorphs of SiO(2) in amorphous silica indicate that the meteorite experienced an equilibrium shock-pressure of at least 8-30 GPa. Secondary quartz grains are also observed in separate amorphous silica grains in the meteorite. The estimated age reported by the (39)Ar/(40)Ar chronology indicates that the source basalt of this meteorite was impacted at 3,800 Ma ago, time of lunar cataclysm; i.e., the heavy bombardment in the lunar surface. Observation of coesite and stishovite formed in the lunar breccias suggests that high-pressure impact metamorphism and formation of high-pressure minerals are common phenomena in brecciated lunar surface altered by the heavy meteoritic bombardment.
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U2 - 10.1073/pnas.1009338108
DO - 10.1073/pnas.1009338108
M3 - Article
C2 - 21187434
AN - SCOPUS:79952272493
VL - 108
SP - 463
EP - 466
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 2
ER -