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Title Transcription
オキ ドウゴ ノ デイシツ ミグマタイト ニ フクマレル リュウタイ ホウユウブツ ノ ケンキュウ
Title Alternative (English)
Fluid Inclusion Study of Pelitic Migmatite from Oki-Dogo Island
File
language
jpn
Author
Kashima, Takashi
Tsunogae, Toshiaki
Description
This study examined composition of fluid inclusions in leucocratic and melanocratic parts of pelitic migmatites from Oki-Dogo to understand fluid activity throughout P-T history of high-T/low-P metamorphic terrane. Calculated fluid density and isochores range from 0.73 to 0.84g/<cm>^^^3 and from 450 to 540℃ at 3kbar, respectively, for H_2O, and from 0.7l to 0.87g/<cm>^^^3 and from 540 to 860℃ for CO_2 inclusions. The temperature range for the
CO_2 inclusions is almost consistent with previously estimated peak and retrograde conditions ; 750~820℃ at l.5~4kbar for peak and 580~630℃ at 2.9~3.9kbar for retrograde conditions. The range for the H_2O inclusions is, however, significantly lower than the retrograde condition. Our results therefore suggest that CO_2-bearing fluid was dominant during peak to retrograde metamorphism, while H_2O-rich fluid infiltrated at the last stage of metamorphism.
Graphite is the most probabie source of CO_2 because the CO_2 inclusion becomes dominant with increasing modal abmdance of graphite in migmatites. Origin of H_2O is not clearly understood, but probably associated with an uplifting of metamorphic terrane providing H_2O-bearing hydrothermal fluid from middle crust. The later H_2O infiltration brought about hydration of garnet and biotite to chlorite and muscovite, which marks the end of thermal events of Oki metamorphic rocks.
Journal Title
Memoirs of the Faculty of Education, Shimane University. Natural science
Volume
31
Start Page
35
End Page
43
ISSN
05869943
Published Date
1997-12-01
NCID
AN00107941
Publisher
島根大学教育学部
Publisher Aalternative
The Faculty of Education Shimane University
NII Type
Departmental Bulletin Paper
OAI-PMH Set
Faculty of Education
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