リフト活動の変遷に伴うマグマ組成の変化　　東北本州，前～中期中新世の秋田‐山形堆積盆地における例

DOI Web Site 被引用文献24件 参考文献88件
  • 八木 正彦
    石油資源開発株式会社技術研究所
  • 長谷中 利昭
    秋田大学工学資源学部附属素材資源システム研究施設
  • 大口 健志
    秋田大学工学資源学部附属素材資源システム研究施設
  • 馬場 敬
    株式会社地球科学総合研究所
  • 佐藤 比奈子
    秋田大学工学資源学部地球資源学科応用地球科学教室
  • 石山 大三
    秋田大学工学資源学部地球資源学科応用地球科学教室
  • 水田 敏夫
    秋田大学工学資源学部地球資源学科応用地球科学教室
  • 吉田 武義
    東北大学大学院理学研究科地学専攻地球物質科学

書誌事項

タイトル別名
  • Transition of magmatic composition reflecting an evolution of rifting activity. A case study of the Akita-Yamagata basin in Early to Middle Miocene, Northeast Honshu, Japan.
  • リフト活動の変遷に伴うマグマ組成の変化--東北本州,前～中期中新世の秋田-山形堆積盆地における例
  • リフト カツドウ ノ ヘンセン ニ トモナウ マグマ ソセイ ノ ヘンカ トウホク ホンシュウ ゼン チュウキ チュウシンセイ ノ アキタ ヤマガタ タイセキ ボンチ ニ オケル レイ
  • Transition of magmatic composition reflecting an evolution of rifting activity—a case study of the Akita–Yamagata basin in Early to Middle Miocene, Northeast Honshu, Japan
  • —— a case study of the Akita-Yamagata basin in Early to Middle Miocene, Northeast Honshu, Japan ——
  • —— 東北本州，前∼中期中新世の秋田—山形堆積盆地における例 ——

この論文をさがす

抄録

Thick piles of basaltic lavas named “Graben-Fill Basalt” (GFB) occurring in the Akita-Yamagata basin characterize the magmatism accompanied by the rifting tectonics during the opening of the Japan Sea. These lavas are products of Miocene volcanism during the Daijima-Nishikurosawa (i.e. rifting) stage, when the tectonic setting transformed from continental arc to island arc. Careful and detailed sampling of GFB and adjacent lavas were undertaken from the drilling cores and surface outcrops for radiometric dating and geochemical analysis. The new data obtained from these lavas helped to establish the geochronological and petrogenetic relationship for the volcanic events in the basin, and revealed a transition of magmatic composition, source character, and tectonic setting during rifting.<br> The rifting event of Daijima-Nishikurosawa period in the Akita-Yamagata basin was divided into two stages, i.e., the early rift (before 16.5 Ma) and the syn-rift (16.5-13.5 Ma). The latter was further divided into three, i.e., “early-”, “middle-”, and “late-” syn-rift stages.<br> The early rift stage is characterized by bimodal volcanism of basalts and felsic welded tuffs that erupted into a terrestrial to very shallow marine environment. The basalts are mainly alkaline with enriched Sr isotopic compositions, containing moderately high to high HFSE, and Th/Hf, Th/Yb and La/Yb ratios are variable. The geochemistry of basalts suggests that they derived from heterogeneous lithospheric mantle source, with different degrees of partial melting events.<br> The syn-rift stage is characterized by the formation of a large-scale graben, resulting from pull-apart tectonism. Intense submarine volcanism took place in the bottom of graben, and formed the thick piles of GFB lavas. Distinctive trace element geochemistry was found among lavas of three different sub-stages. Chondrite normalized LREE patterns of GFB with depleted Sr isotopic compositions change from low, to medium, then to medium high values. The ratios of Th/Hf and La/Yb show little variation within each sub-stage, however, the averaged ratios do increase from the early to the late-stage. The compositional change from alkali basalts of early syn-rift stage to tholeiites of middle syn-rift stage suggested the compositional change of the source from depleted to more enriched.<br> Injection of the asthenospheric depleted mantle probably caused the production of the GFB. The variation in trace element composition between different syn-rifting sub-stages also indicates the change of partial melting degree of mantle, from low, to high, then to medium low, which is consistent with the progressive prosper and decline of active rifting in the Akita-Yamagata basin.

収録刊行物

  • 岩石鉱物科学

    岩石鉱物科学 30 (6), 265-287, 2001

    一般社団法人　日本鉱物科学会

被引用文献 (24)*注記

もっと見る

参考文献 (88)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ