宮城県白石産球状岩 An orbicular rock from Shiroishi, Miyagi Prefecture

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著者

    • 秋月 瑞彦 AKIZUKI Mizuhiko
    • 東北大学理学部地球物質科学科 Institute of Mineralogy, Petrology and Economic Geology, Faculty of Science, Tohoku University
    • 長瀬 敏郎 NAGASE Toshiro
    • 東北大学理学部地球物質科学科 Institute of Mineralogy, Petrology and Economic Geology, Faculty of Science, Tohoku University
    • 藤巻 宏和 FUJIMAKI Hirokazu
    • 東北大学理学部地球物質科学科 Institute of Mineralogy, Petrology and Economic Geology, Faculty of Science, Tohoku University

抄録

Orbicular rock from Inusotoba, Shiroishi, Miyagi Prefecture was studied by optical and chemical methods. The orbicules, which are 5∼20 cm in diameter, are divided into two parts, — core and shell. The core is ball-shaped and dark-colored, and consists mainly of fibrous hornblende and chlorite. The shell, which surrounds core, is light-colored and consists of coarse radial anorthite crystals less than l cm long, which are elongated to a-axis. These radial crystals are characterized by micro subgrains of albite twin and parallel-growing crystals. The other type of orbicule is also known, whose shell consists of several alternate layers of mafic and felsic minerals. This latter type of orbicules is never produced together with the former radial type. The matrix, solidified among orbicules, has a heterogeneous texture, which consists of the dark-part of poikilitic hornblende and the light-part rich in euhedral plagioclase.<br>     The forming environment of orbicular rocks is featured by many close-packed orbicules, the flow structure of felsic mineral assembledge in matrix and unmixing of magma including orbicules with the other magma containing plagioclase spherulites. It is considered that orbicules were formed in supercooling magma possibly due to income of another magma.

収録刊行物

  • 岩鉱 : 岩石鉱物鉱床学会誌 : journal of mineralogy, petrology and economic geology  

    岩鉱 : 岩石鉱物鉱床学会誌 : journal of mineralogy, petrology and economic geology 90(4), 124-131, 1995-04-05 

    Japan Association of Mineralogical Sciences

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各種コード

  • NII論文ID(NAID)
    10002029127
  • NII書誌ID(NCID)
    AN10047992
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    09149783
  • NDL 記事登録ID
    3610369
  • NDL 刊行物分類
    ME41(火山・岩石)
  • NDL 雑誌分類
    ZM46(科学技術--地球科学--岩石・鉱物・鉱床)
  • NDL 請求記号
    Z15-71
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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