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Title Transcription
オガサワラ チチジ マムジンイワ ノ キサイ ガンセキ ガクテキ ケンキュウ : ムジン イワ マクラジョウ ヨウガン ノ スイチョク ヘンカ
Title Alternative (English)
Petrological Characteristics of Boninite from Chichijima Island, Ogasawara, Japan : Vertical Petrological Diversity of Boninite Pillow Lava
File
language
jpn
Attribute
Natural Science
Author
Taku, Masahiro
Description
Chichijima, Ogasawara Islands is the place where boninite has been exposed most voluminously all over the world. Moreover, it is “type locality” of boninite. Boninite is high-magnesian andesite (HMA) which is a primary andesite basis of its high Mg, Ni and Cr content, directly derived from mantle. We did detailed research and sampling of boninite based on geological map of Chichijima (Umino and Nakano, 2007) and clarified and classified petrographic characteristics of boninite. Uminio (1986) classified aphyric boninite from Chichijima into five types: (I) olivine (ol) + clinoenstatite (cen) + bronzaite (brz); (II) ol + brz; (III) brz; (IV) brz + pigeonite (pig) + augite (aug); (V) cen + brz. We can classified the type (II) of Umino (1986) divided into four types by phenocryst and micro-phenocryst assemblage. They are Type AI (phenocryst: (ol + serpentine (ser)) / brz ≧1 and micro-phenocryst: brz / clinopyroxene (cpx) ≧1), Type AII (phenocryst: (ol + serpentine (ser)) / brz ≧1 and micro-phenocryst: brz / clinopyroxene (cpx) < 1), Type BI (phenocryst: (ol + serpentine (ser)) / brz < 1 and micro-phenocryst: brz / clinopyroxene (cpx) ≧1 ) and Type BII (phenocryst: (ol + serpentine (ser)) / brz <1 and micro-phenocryst: brz / clinopyroxene (cpx) <1 ). It has been understood that the above four types rock appears in respective height in the pillow lava bed.
Journal Title
島根大学教育学部紀要
Volume
43
Start Page
123
End Page
135
ISSN
18808581
Published Date
2009-12-25
NCID
AA12171265
DOI(SelfDOI)
Publisher
島根大学教育学部
Publisher Aalternative
Faculty of Education Shimane University
NII Type
Departmental Bulletin Paper
Format
PDF
Text Version
出版社版
OAI-PMH Set
Faculty of Education
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