The Cape Hinode area in East Antarctica exposes Mid-Proterozoic tonalites, which are similar in chemical composition to high-SiO₂ adakites and Archean tonalite-trondhjemite-granodiorite. They contain enclaves of ultrabasic-intermediate and calc-silicate metamorphic rocks of various dimensions, as well as xenocrystic garnet and kyanite. Pinite and carbonate minerals surrounding kyanite inclusions in plagioclase are alteration products after coronas of anorthite and spinel with or without corundum, alkali feldspar, rutile and magnetite. Further observations reveal that thin tonalitic veins cutting calc-silicate enclaves carry kyanite fringed by similar anorthite coronas. Such kyanite sometimes encloses quartz inclusions. The thin tonalitic veins are characterized by the occurrence of dark green clinopyroxene as the main mafic mineral, low aluminum saturation index (0.75) in spite of the occurrence of kyanite, and a non-adakitic geochemistry.
  The calc-silicate enclaves in tonalites are composed mainly of calcic plagioclase, Ca-garnet and/or clinopyroxene. The symplectitic intergrowth of anorthite and Ca-garnet is chemically close to epidote, and may be produced by successive melt-involving and epidote-consuming reactions. These chemical and textural features of kyanite and other minerals occurring in and around kyanite, thin tonalitic veins, calc-silicate enclaves, and tonalites indicate the significance of metamorphic and magmatic epidotes during partial melting of eclogites of young and hot slab origin.

抄録全体を表示

  The Tadamigawa granitic rocks are located at southwestern part of Fukushima prefecture, northeastern Japan. The granite intrudes into Jurassic sedimentary complex of the Ashio terrane. The granites around the Hinoemata village area are divided into two rock types: the Tadamigawa granite and the Hinoematagawa granite. On the field occurrence, the Tadamigawa granite intrudes into the Hinoematagawa granite. In this study, 7 samples of the Hinoematagawa granite and 32 samples of the Tadamigawa granite were analyzed for major, minor and REE compositions by XRF and ICP-MS, respectively. Moreover, we obtained K-Ar biotite ages from both granites, and iron oxidation ratios by titrimetry with potassium permanganate. SiO₂ contents of the Hinoematagawa granite and the Tadamigawa granite range from 59.6 to 69.4 wt% and from 62.5 to 76.1 wt%, respectively. K-Ar biotite ages of the Hinoematagawa granite and the Tadamigawa granite at Taishaku Mountains are 102.3 ± 2.2 Ma and 102.7 ± 2.2 Ma, respectively. However, the Tadamigawa granite at Inagawa area and Tadamigawa area show the ages of 61.7 ± 1.4 Ma and 89.6 ± 1.9 Ma, respectively. The granites are characterized by LREE enrichment, and have relatively constant patterns normalized by CI chondrite. The Hinoematagawa granite shows small negative Eu anomaly (Eu/Eu^* = 0.73-1.01), and the Tadamigawa granite show large Eu anomaly (Eu/Eu^* = 0.26-0.89). The value of Eu anomaly increases with decreasing anorthite content and the Eu anomaly might be concerned with the differentiation of anorthite. The Hinoematagawa granite and the Tadamigawa granite may be generated from the same magma origin. The Hinoematagawa granite shows low Fe₂O₃/FeO ratio (0.28-0.39), however, the Tadamigawa granite shows high Fe₂O₃/FeO ratio (0.24-1.45). The Hinoematagawa granite may be generated from the magma which has low oxygen fugacity. The difference between both granites is concerned with oxygen fugacity variation of source magma.

抄録全体を表示

  「絵でわかるプレートテクトニクス」

抄録全体を表示

  日本鉱物科学会平成 25 年度第 3 回定例評議員会議事録
  日本鉱物科学会平成 25 年度総会記事
  平成 25 年度日本鉱物科学会賞第 11 受賞者
  平成 25 年度日本鉱物科学会賞第 12 受賞者
  渡邉萬次郎賞第 30 回受賞者
  平成 25 年度日本鉱物科学会論文賞第 14 回受賞者
  平成 25 年度日本鉱物科学会論文賞第 15 回受賞者
  平成 25 年度日本鉱物科学会研究奨励賞第 13 回受賞者
  平成 25 年度日本鉱物科学会研究奨励賞第 14 回受賞者
  平成 25 年度日本鉱物科学会研究奨励賞第 15 回受賞者
  平成 25 年度日本鉱物科学会応用鉱物科学賞第 7 回受賞者
  櫻井賞第 41 回受賞者
  日本鉱物科学会平成 26 年度第 1 回定例評議員会議事録

抄録全体を表示