| 概要 |
There is an amphibolite xenolith with rodingite shell in a serpentinite body of the Kurosegawa tectonic zone at Tsubokinohana, Kumamoto Prefecture. Four metasomatic reaction zones are well developed a...t the border of the xenolith: incipient prehnite zone (A), prehnite zone (B), hydrogrossular-clinopyoxene zone (C) and chlorite zone (D) from core to margin of the xenolith. Initial alteration of the amphibolite is partial prehnitization of plagioclase in the zone A. The zones B and C are characterized by prehnite after plagioclase, and by hydrogrossular after prehnite and clinopyroxene after hornblende, respectively. The zone D adjacent to the serpentinite may be formed by chloritization of the clinopyroxene and hydrogrossular from the rodingite of the zone C. EPMA analyses of rocks show marked increase of Ca and decrease of Si, Al and alkalis with increasing metasomatic alteration. The hydrogrossular may be intermediate members of the grossular-hibschite series according to EPMA analyses. Additional mineral analyses are given of prehnite, clinopyroxene, serpentine, garnet and hornblende. The reaction zones are regarded as the result from metasomatic interchange of elements between the amphibolite and serpentinite during serpentinization of original ultramafic rock accompanied by the Kurosegawa tectonic movement.続きを見る
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Mendeley出力
