島原半島南部に分布する玄武岩・安山岩類の成因関係

• 中田 節也

  九州大学理学部地質学教室

• 鎌田 浩毅

  工業技術院地質調査所(地毅熱部):(現)米国地調カスケード火山観測所

書誌事項

タイトル別名

• Petrogenetical Relationship of Basalts and Andesites in Southern Part of the Shimabara Peninsula, Kyushu, Japan
• シマバラ ハントウ ナンブ ニ ブンプスル ゲンブガン アンザンガンルイ ノ

抄録

Volcanism and deposition of volcaniclastic materials within a graben in the Shimabara area, western Kyushu, started in early Pliocene and have continued up to the present. The volcanic products comprise alkalic to high-alkali tholeiitic basalts in addition to calc-alkalic andesites. The basalts are of a member of magmas erupted extensively in NW Kyushu from late Miocene to Recent. Their incompatible-element patterns in spider gram, in which the abundances of Rb, Ba, K, Nb, Zr and Y are normalized to those of MORB, are uniform independently of their eruption-ages, and show positive Ba and Nb anomalies strongly indicative of the marked affinity with ocean-island basalts. These patterns are clearly different from those of island-arc basalts which have negative Nb anomaly, as represented by the Quaternary high-alumina basalts in central Kyushu, and from those of back-arc basin basalts usually showing the same anomaly. It is concluded that basaltic magmas in NW Kyushu were derived from partial melt of fertile mantle with high Nb/Zr. Most of the andesites in the Shimabara area have phenocryst assemblages showing co-existence of magmas with different compositions. This fact and the spidergram pattern without Nb anomaly of the andesites lead us to a magmatic model; the andesite magma originated from mixing of positive-Nb-anomaly basaltic melt with negative-Nb-anomaly acidic partial melt of lower-crust materials which were presumably heated by the former melt. The graben in the Shimabara area seems to have developed in southern periphery of the region under which fertile mantle materials have been rising up from the depth and the subducted oceanic slab has not reached, like the “hot region”.

収録刊行物

• 火山.第２集

  火山.第２集 33 (4), 273-289, 1988

  特定非営利活動法人 日本火山学会

詳細情報

• CRID: 1390001206122605568
• NII論文ID: 10004024476
• NII論文ID: 110002989349
• NII書誌ID: AN10512786
• ISSN: 04534360
• ISSN: 24330590
• DOI: 10.18940/kazanc.33.4_273
• NDL書誌ID: 3230204
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I3230204
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可