北部フォッサマグナ，関田山脈–志久見川流域に分布する前期更新世火山岩類の岩石学的特徴<br/>─ソレアイト系列火山岩類の形成過程─

• 五十嵐 聡

  法政大学第二中・高等学校

• 有馬 眞

  横浜国立大学環境情報研究院

• 木村 純一

  海洋研究開発機構

• 周藤 賢治

  新潟大学理学部

書誌事項

タイトル別名

• Petrogenesis of the early Pleistocene volcanic rocks in the Sekita Mountains and the Shikumi river basin, North Fossa Magna, Central Japan<br/>—Differentiation process of tholeiitic basaltic magma—
• 北部フォッサマグナ,関田山脈-志久見川流域に分布する前期更新世火山岩類の岩石学的特徴 : ソレアイト系列火山岩類の形成過程
• ホクブ フォッサマグナ,カンデン サンミャク-シキュウケンガワ リュウイキ ニ ブンプ スル ゼンキ コウシン セイ カザンガンルイ ノ ガンセキガクテキ トクチョウ : ソレアイト ケイレツ カザンガンルイ ノ ケイセイ カテイ
• Petrogenesis of the early Pleistocene volcanic rocks in the Sekita Mountains and the Shikumi river basin, North Fossa Magna, Central Japan<br/>^|^mdash;Differentiation process of tholeiitic basaltic magma^|^mdash;

抄録

  The Sekita Mountains and Torikabuto Volcano District lies at the northeastern end of the Central Upheaval Zone located within the North Fossa Magna region. In this area, early Pleistocene volcanic rocks ranging basaltic to dacitic compositions are widely distributed. These volcanic rocks are subdivided into four distinct groups, based on their geological and geochemical characteristics, the Sekita Mountains (SM), the Shikumi River Basin (SRB), the Kenashi (KN) volcano and the Torikabuto (TK) volcano.<br>   In this paper we report petrographical, mineralogical, whole rock geochemical, and Sr- and Nd- isotopic characteristics of the SM and SRB volcanic rocks. The SM and SRB volcanic rocks are divided into group 1 and group 2, and these volcanic rocks are composed mainly of basalt, andesite and dacite belonging to the tholeiitic rock series. The ages of SM and SRB rocks range from ∼2 Ma to 1.3 Ma. Our data can concluded as the followings. 1) The SM and SRB volcanic rocks were formed by fractional crystallization processes of tholeiitic magma, involving plagioclase, clinopyroxene, orthopyroxene, and Fe-Ti oxides. 2) The Sr- and Nd-isotopic compositions of the SM and SRB tholeiitic volcanic rocks are nearly identical to that of the TK calc-alkaline volcanic rocks, suggesting a genetic link between the SM, SRB and TK rocks. 3) The tholeiitic primary magmas for the SM and SRB volcanic rocks and the calc-alkaline primary magmas for the TK rocks would be formed by partial melting processes of the mantle source materials having similar Sr- and Nd-isotopic composition. We interpret that the tholeiitic rocks are products of crystal differentiation at middle crustal level (∼5 kbar), while the calc-alkaline rocks are derived by fractional crystallization at shallower level (2–3 kbar).<br>

収録刊行物

• 岩石鉱物科学

  岩石鉱物科学 41 (4), 103-121, 2012

  一般社団法人　日本鉱物科学会

キーワード

• North Fossa Magna
• Sekita Mountains
• Shikumi river basin
• Tholeiitic volcanic rocks
• Sr-Nd isotopic compositions

詳細情報

• CRID: 1390001206525475456
• NII論文ID: 10030868540
• NII書誌ID: AA1146088X
• DOI: 10.2465/gkk.100427
• COI: 1:CAS:528:DC%2BC38XhsFOqtrfL
• ISSN: 13497979
• ISSN: 1345630X
• NDL書誌ID: 023982953
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I023982953
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可