このエントリーをはてなブックマークに追加
ID 13957
JaLCDOI
Sort Key
4
フルテキストURL
著者
岡野 修 The Graduate School of Natural Science and Technology, Okayama University
西谷 七代 Department of Earth Sciences, Okayama University
加々美 寛雄 Institute for study of Earth's Interior, Okayama University
抄録
Rb-Sr isotopic study as well as petrologic investigations have been done on sixteen individul chondrule samples separated from the Allegan (H5) chondrite. The Rb-Sr chondrule isochron does not define a very precise age (4.42±0.17 Ga) and 87Sr/86Sr initial ratio (0.6997±0.0014) due to the very small variation in Rb/Sr ratio for the chondrules, whereas the model ages give a much more speciffic value (4.42±0.02 Ga). These ages may probably be indicative of the time of primary process (es) (e.g. chondrule formation) rather than secondary (metamorphic reheating) or tertiary (shock heating) processes in and/or on the H-chodrite parent body (or bodies). Chemical compositions of oliveines (Fa=17.5mol%, mean deviation (MD)=1.3%) and orthopyoxenes (Fs=15.4mol%, MD=3.2%) are moderately homogenized among the chondrules, while certains chemically uneguilibrated features are also distinctly preserved in this chondrite. Homogeneity of the mineral compositions, therefore, could not have been caused by thermal metamorphism but were probably inherited from processes prior to aggregation of the components. The overall implications of the chondrule isochron and model ages in relation to the petrological features and in comparison with Rb-Sr data of other chondrites of different chemical groups and petrologic types are discussed.
キーワード
chondrule
age
Rb-Sr isochron
Allegan
H- chondrite
meteorite
metamorphism
olivine
pyroxene
出版物タイトル
Okayama University Earth Science Report
発行日
1994-09-20
1巻
1号
出版者
岡山大学理学部地球科学教室
出版者(別表記)
Department of Earth Sciences Faculty of Science, Okayama University
開始ページ
27
終了ページ
36
ISSN
1340-7414
NCID
AN10506284
資料タイプ
紀要論文
OAI-PMH Set
岡山大学
言語
English
著作権者
岡山大学地球科学研究報告編集委員会
論文のバージョン
publisher
NAID
Eprints Journal Name
esr