鉱物組成からみた北九州アルカリ玄武岩類 : 特に角閃石含有岩類の成因に関連して

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概要

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• In order to study the origin of amphibole in alkali basalts, the writer has statistically treated the mineral compositions of basaltic rccks from northern Kyushu, belonging to the "Cenozoic alkali suite of Circum-Japan Sea Region (TOMITA 1935)". It is always the case that the amphibole-bearing rock is accompanied by the amphibole-free basalt, and the latter is intruded or overlaid by the former. Hence the basalts are classified into the olivine trachybasalt〜trachyandesite without amphibole phenocryst (III_b and IV_b types as defined by H. KUNO), and the amphibole-bearing olivine trachybasalt〜trachyandesite (VIII_b and IX_b types). Significant differences are noticed between these two types with respect to modal olivine as modal magnetite. Petrochemistry of these two types shows no significant differences between the two types with respect to their ratios. FeO + Fe_2O_3/MgO + FeO + Fe_2O_3, or Fe_2O_3 + TiO_2/FeO + Fe_2O_3 + TiO_2, which are regarded as the indicator of the content of magnetite (+ilmenite). Within the amphibole-bearing rocks, there is a negative correlation between the contents of amphibole and magnetite + ilmenite. From these considerations, the writer is lead to the conclusion that the amphibole is formed by the crystallization of magma during which the iron and titanium components concentrate into the ampoiboles, and consequently the separation of ore minerals is restricted.

• 特定非営利活動法人日本火山学会の論文
• 1964-12-25

著者

• 竹下 寿

  福岡県立門司高等学校

関連論文

• 1. 溶岩の記載とその成因(VI. 秋田駒ケ岳 1970-71 年噴火の噴出物)
• 鉱物組成からみた北九州アルカリ玄武岩類 : 特に角閃石含有岩類の成因に関連して
• 火山岩中の斜長石の組成と大きさとの相関
• 鉱物組成からみた北九州のアルカリ玄武岩類,特に角閃石含有岩類の成因に関連して : 日本火山学会1963年度春季大会講演要旨
• 火山岩中における斜長石の大きさ : 成分関係について : 1958年秋季大会講演要旨

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