2006•Institutional Repository National Institute of Polar Research (National Institute of Polar Research (Japan))Requires access
Sm-Nd Isotopic Systematics of Lherzolitic Shergottite Yamato-793605
K. Misawa, Kazushi Yamada, Noboru Nakamura, Noritoshi Morikawa, G. Kondorosi, Katsuyuki Yamashita, Wayne R. Premo
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Abstract
We have undertaken Sm-Nd isotopic studies on Yamato-793605 lherzolitic shergottite. The Sm-Nd internal isochron obtained for acid leachates and residues of whole-rock and separated mineral fractions yields an age of 185±16Ma with an initial εNd value of +9.7±0.2. The obtained Sm-Nd age is, within analytical errors, identical to the Rb-Sr age of this meteorite as well as to the previous Rb-Sr and Sm-Nd ages of Allan Hills-77005 and Lewis Cliff 88516, although the ε_(Nd) values are not identical to each other. Elemental abundances of lithophile trace elements remain nearly unaffected by aqueous alteration on the Martian surface. The isotopic systems of lherzolitic shergottites, thus, are considered to be indigenous, although disturbances by shock metamorphism are clearly observed. "Young ages of ～180Ma" have been consistently obtained from this and previous Rb-Sr, Sm-Nd and U-Pb isotopic studies and appear to represent crystallization events.