関東ロームの地球化学的研究 : 軽石中に含まれる強磁性鉱物の一般的性質

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概要

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• Hitherto, various reports on the stratigraphy, geomorphology and mineralogy of the Kanto volcanic ash have been published, however, any geochemical study of it has never been known. So the writer has performed the study on this line, in order to get some new criteria from view for the determination of its geological horizon and their origin, and for the clearance of mechanics of their effusions. Selecting the ferromagnetic minerals, as an index mineral of the former facts, he studied the general characters of chief pumice layers embeded in the Kanto volcanic ashes in whole Kanto district. Most of ferromagnetic minerals included in the pumice layers, are titanomagnetite belonging to FeOFe_2O_3-TiO_2 system with spinel structure and posses the chemical composition which deviates considerably from TiFe_2O_4-Fe_3O_4 join towards TiFeO_3Fe_2O_3 join side. And it is common that a few ferromagneilmenite coexist in titanomagnetite as lamellae. He found that the chemical composition of titanomagnetite belonging to the same geological horizon are varied due to their grain size, and he considered the course of it. In one pumice layer, TiO_2 content decrease gradually from the bottom to the top of it. And especially in a pumice layer covering wide area, the former change of TiO_2 content repeat twice or three times. Most of pumice layer belonging to the same geological horizon, though the covering area of them is varied, have the same chemical composition of ferromagnetic minerals. There fore their chemical composition are able to use as a criteria for the determination of their geological horizon. But their chemical composition are often allied in spite of the difference of their geological horizon, so it is difficult to decide at once their horizon and origin from the chemical composition of them. From the view point of the mechanics of effusion of voluminous pumice fall, however it is interesting fact that they have allied chemical composition in spite of their variance of their geological horizon.

• 地学団体研究会の論文
• 1970-01-25

著者

• 青柳 隆二

  川崎市立宮崎中学校

関連論文

• 強磁性鉱物中の微量成分によるテフラの同定法
• 南関東における第4紀中・後期の示標テフラ層に含まれる鉄-チタン酸化鉱物の特性
• 関東ロームの地球化学的研究 : 軽石中に含まれる強磁性鉱物の一般的性質
• 中学校における科学クラブ活動 : 多摩川およびその流域の水質調査を中心として
• 強磁性鉱物の主成分によるテフラの同定の基礎的研究
• 関東および信州ローム中のチタン磁鉄鉱の化学組成と共存する有色鉱物との関係
• 南関東における第4紀中・後期の示標テフラ層に含まれる鉄-チタン酸化鉱物の特性

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