Item type |
紀要論文(ELS) / Departmental Bulletin Paper(1) |
公開日 |
1990-09-01 |
タイトル |
|
|
タイトル |
EXPERIMENTAL STUDY OF THE SYENITIC ROCKS FROM THE YAMATO AND SØR RONDANE MOUNTAINS, EAST ANTARCTICA |
言語 |
|
|
言語 |
eng |
資源タイプ |
|
|
資源タイプ識別子 |
http://purl.org/coar/resource_type/c_6501 |
|
資源タイプ |
departmental bulletin paper |
ID登録 |
|
|
ID登録 |
10.15094/00002638 |
|
ID登録タイプ |
JaLC |
ページ属性 |
|
|
内容記述タイプ |
Other |
|
内容記述 |
P(論文) |
記事種別(英) |
|
|
|
en |
|
|
ABSTRACT |
著者名よみ |
オオバ, タカノブ
シライシ, カズユキ
|
著者名(英) |
OBA, Takanobu
SHIRAISHI, Kazuyuki
|
著者所属(英) |
|
|
|
en |
|
|
Department of Geoscience, Joetsu University of Education |
著者所属(英) |
|
|
|
en |
|
|
National Institute of Polar Research |
抄録(英) |
|
|
内容記述タイプ |
Other |
|
内容記述 |
The melting relationships of five syenites from the Yamato and Sør Rondane Mountains were determined in the temperature range of 650-850℃, under the water pressure of 1-2 kbar and oxygen fugacities of the FMQ buffer. The syenites studied are samples from the Yamato Mountains (Nos. 73120904 : Y904 and 73120405 : Y405) and from the Sør Rondane Mountains (Nos. 85012101A : SR-A, 85012103B : SR-B and 85012103C : SR-C). They are composed of porphyritic K-feldspar, plagioclase, quartz, biotite, Ca-amphibole or Ca-Na amphibole, clinopyroxene, sphene, ilmenite and rarely magnetite. Though the syenites from both regions consists of the same mineral assemblages, the compositions of amphiboles are various as follows; Ca-amphibole in the syenite (Y904) from the Yamato Mountains is close to edenitic. On the other hand, the bluish green hornblende in the mafic layer (SR-B) and the leucocratic layer (SR-C) from the Sør Rondane Mountains is richteritic actinolite. In the porphyritic syenite (Y405) and the leucocratic syenite (SR-A) intruding the layered syenites (SR-B and SR-C), the Ca-amphibole is pargasitic hornblende. The solidus temperatures of the syenites from the Sør Rondane Mountains are about 770℃ at 1 kbar. With increasing temperature, plagioclase (albite) and quartz disappeared in the lower temperature range than K-feldspar, hornblende, biotite and clinopyroxene. Clinopyroxene, biotite and K-feldspar are stable at 850℃ under the water pressure of 1 kbar. Richteritic actinolite in two layered syenites (SR-B and SR-C) becomes unstable at slightly higher temperature than solidus at 1 kbar. Pargasitic hornblende from syenite (SR-A) is stable at 825℃ and 1 kbar, and it disappears at 775℃ and 1.7 kbar. Representative results of syenites from the Yamato Mountains at 1 kbar are : clinopyroxene quartz syenite (Y904) begins to melt at 680℃, quartz and plagioclase disappear at 710℃, edenitic hornblende disappears at 775℃, K-feldspar disappears at 825℃, clinopyroxene hornblende quartz syenite (Y405) begins to melt at 760℃, plagioclase and quartz disappear at 780℃, K-feldspar disappears at 830℃, hornblende appears at 850℃. In both rocks, clinopyroxene and biotite remain at 850℃. The composition of edenitic hornblende shifts to actinolite-pargasite join with increasing temperature under water pressure. The result suggests that edenite end member is unstable under high water pressure in a preliminary synthesized experiment. Pargasitic hornblende from two syenites (SR-A and Y405) are both stable at 825℃ and 1 kbar. At 1.6 kbar the hornblende (Y405) is stable at 825℃, while the other hornblendes is unstable at 800℃.All rocks investigated are at least 40% melted at temperatures 50℃ above the solidus. The approximate K-feldspar content of the syenite is about 30%. The compositions of K-feldspar are Ab_<40>Or_<60> and Ab_5Or_<95> at 800℃ and 700℃, respectively. As compared to biotite, the behavior of K-feldspar is important to concentrate K_2O content of syenite. |
雑誌書誌ID |
|
|
収録物識別子タイプ |
NCID |
|
収録物識別子 |
AA1072335X |
書誌情報 |
Proceedings of the NIPR Symposium on Antarctic Geosciences
巻 4,
p. 242,
発行日 1990-09
|
出版者 |
|
|
出版者 |
National Institute of Polar Research |