Petrology and mineralogy of the shock-melted H chondrites Yamato–791088 and LaPaz Ice Field 02240
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概要
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We studied the petrology and mineralogy of two types of shock-melted H chondrites: Yamato (Y)–791088 and LaPaz Ice Field (LAP) 02240. Y–791088, which consists of numerous coarse-grained relict phases (40%) and euhedral fine-grained minerals solidified from the shock melt (60%), experienced incomplete melting; a quiescent melt is indicated by the existence of abundant relict phases, pseudomorphed chondrules, and two types of glass. LAP 02240, which consists of small amounts of coarse-grained relict phases (10%) and fine-grained minerals (90%), experienced near-complete melting; a rapidly cooled mobilized melt is indicated by the homogeneous compositions of glass and opaque veins.The homogeneous compositions of relict olivines indicate that the precursors of both chondrites were equilibrated H chondrites. The melting features of Y–791088 and LAP 02240 are very similar to those of Y–790964 (LL) and the fine-grained lithology of Y–790519 (LL), respectively. These two types of shock-melted ordinary chondrites possibly formed in situ during dike formation. The quiescent melt is thought to have originated from the injection of shock-heated chondrite blocks into mobilized melt. These two types of melting could have occurred during dike formation on the H chondrite parent body. The textures of the two types of shock melts were not simply affected by the degree of shock melting: they were also controlled by the degree of shear stress.
著者
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Takafumi Niihara1
Department of Polar Science, The Graduate University for Advanced Studies, 10–3, Midori-cho, Tachika
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Naoya Imae2
Antarctic Meteorite Research Center, National Institute of Polar Research, 10–3, Midori-cho, Tachika
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Keiji Misawa2
Antarctic Meteorite Research Center, National Institute of Polar Research, 10–3, Midori-cho, Tachika
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Hideyasu Kojima2
Antarctic Meteorite Research Center, National Institute of Polar Research, 10–3, Midori-cho, Tachika
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Naoya Imae2
Antarctic Meteorite Research Center National Institute Of Polar Research 10–3 Midori-cho Tachi
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Keiji Misawa2
Antarctic Meteorite Research Center National Institute Of Polar Research 10–3 Midori-cho Tachi
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Hideyasu Kojima2
Antarctic Meteorite Research Center National Institute Of Polar Research 10–3 Midori-cho Tachi
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Takafumi Niihara1
Department Of Polar Science The Graduate University For Advanced Studies 10–3 Midori-cho Tachi
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Takafumi Niihara
Department of Polar Science, The Graduate University for Advanced Studies, 10-3, Midori-cho, Tachika
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Naoya Imae
Antarctic Meteorite Research Center, National Institute of Polar Research, 10-3, Midori-cho, Tachika
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Keiji Misawa
Antarctic Meteorite Research Center, National Institute of Polar Research, 10-3, Midori-cho, Tachika
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Hideyasu Kojima
Antarctic Meteorite Research Center, National Institute of Polar Research, 10-3, Midori-cho, Tachika
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Keiji Misawa
Antarctic Meteorite Research Center National Institute Of Polar Research 10-3 Midori-cho Tachikawa-s
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Naoya Imae
Antarctic Meteorite Research Center National Institute Of Polar Research 10-3 Midori-cho Tachikawa-s
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Hideyasu Kojima
Antarctic Meteorite Research Center National Institute Of Polar Research 10-3 Midori-cho Tachikawa-s
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Takafumi Niihara
Department Of Polar Science The Graduate University For Advanced Studies 10-3 Midori-cho Tachikawa-s