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>A reply to the comments on 'Garnet-bearing spinel harzburgite xenolith from Arato-yama alkali basalt, southwest Japan by Yamamoto et al.'
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A reply to the comments on 'Garnet-bearing spinel harzburgite xenolith from Arato-yama alkali basalt, southwest Japan by Yamamoto et al.'
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机译：A reply to the comments on "Garnet-bearing spinel harzburgite xenolith from Arato-yama alkali basalt, southwest Japan by Yamamoto et al."
In order to determine their Sr isotopic ratios, we have manually selected clinopyroxene grains taken from mantle peridotite xenoliths. The Arato-yama harzburgite sample was all crushed or hand-picking because it was too small to allow preparation of thin section. The garnet grains in this sample were found under a binocular microscope.The clinopyroxene of the above Arato-yama sample is relatively low in CaO and appears to have relatively high equilibrium temperature within the low temperature group peridotites (Fig.2 f Yamamoto et al., 1999). The Arato-yama mantle peridotites as a whole, however, still belong to the low temperature group in the same way as do the Kurose, On-yama and Megata peridotites (Fig.3 of Yamamoto et al., 1999). This result is consistent with the temperatures estimated by Arai and Hirai (1983) and Abe and Arai (2001) who applied the same geothermometer to the Noyama-dake (high temperature group), Kurose and Arato-yama mantle peridotites.Orthopyroxenes of the low temperature group peridotites (Arato-yama and other peridotites) are characteristically low in Al_2O_3. This suggests a different geothermal gradient from that of the Fukue-jima peridotites which include high Al_2O_3 orthopyroxenes even in shallow seated origin.
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