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フルテキストURLKJ00000199470.pdf ( 1.2MB ) 公開日 2010-04-19
タイトル<研究報告>長崎県西彼杵半島南部の高Mg安山岩と玄武岩
タイトル別表記High-Mg andesites and basalts in the southern Nishisonogi Peninsula, Nagasaki Prefecture
作成者白木, 敬一
宮本, 光隆
松尾, 弘昭
植木, 有子
東, 高照
永尾, 隆志
松本, 征夫
田島, 俊彦
作成者ヨミシラキ, ケイイチ
ミヤモト, ミツタカ
マツオ, ヒロアキ
ウエキ, ユウコ
アズマ, タカテル
ナガオ, タカシ
マツモト, ユキオ
タジマ, トシヒコ
作成者別表記Shiraki, Keiichi
Miyamoto, Mitsutaka
Matsuo, Hiroaki
Ueki, Yuko
Azuma, Takateru
Nagao, Takashi
Matsumoto, Yukio
Tajima, Toshihiko
作成者所属山口大学機器分析センター
内容記述(抄録等)The late Cenozoic volcanic rocks in the southern Nishisonogi Peninsula, which are characterized by dominance of undifferentiated, primitive rocks, show a large variation in chemical composition ranging from high-Mg andesite (HMA) through tholeiitic basalt to alkali basalt and from high-Mg basalt to rhyolite. Most HMA is cpx-HMA crystallized clinopyroxene with the highest Mg# and Cr_2O_3 of 87.4 and 1.24%, respectively, following olivine with the highest Fo of 92.1 and NiO of 0.48%. An orthopyroxene andesite containing bronzite with Mg# and Cr_2O_3 as high as 89.5 and 1.06%, respectively, was found at Ebisu-zaki, the second opx-HMA occurrence in this area. Many of the pyroxene andesites reveal high Cr (>100ppm) ; they are likely to have derived from HMA magmas through crystal fractionation. Shikimi basalt with SiO_2 49.0~49.9% and MgO 13.3~12.6% has olivine showing a modal Fo value of 74-71,suggesting that its high MgO results from accumulation of olivine. Makishima alkali basalt is distinguishable from the dominant tholeiitic and calc-alkali rocks by high incompatible element abundances, especially Nb (40.9~25.4ppm), implying derivation from intra-plate magmas. Coexistence of alkali basalt and tholeiitic basalt to HMA suggests that their magmas have generated by reaction between rising magmas and mantle materials variously metasomatized previously by slab-derived hydrous fluids and/or siliceous melts. The least modified Makishima alkali basalt may represent the least reacted magmas, and reaction with intensively metasomatized hydrous, siliceous mantle has produced the most SiO_2-rich opx-HMA magmas.
本文言語jpn
資料タイプtext
ファイル形式application/pdf
出版者山口大学機器分析センター
出版者ヨミヤマグチ ダイガク キキ ブンセキ センター
NII資料タイプ紀要論文
NCIDAN1046804X
学内刊行物(紀要等)山口大学機器分析センター報告
掲載誌名山口大学機器分析センター報告
掲載誌名別表記Center of Instrumental Analysis, Yamaguchi University
8
開始ページ24
終了ページ37
発行日2000
著者版/出版社版出版社版
備考本文データは国立情報学研究所において電子化したものである
リポジトリIDKJ00000199470
地域区分山口大学
URIhttp://www.lib.yamaguchi-u.ac.jp/yunoca/handle/KJ00000199470