Characterization of Ar-degassing from Antarctic meteorites
スポンサーリンク
概要
- 論文の詳細を見る
Based on the Ar-degassing patterns from the Antarctic meteorites, it is intended to find some relationships between the types of Ar-degassing and the states of Antarctic meteorites. For this purpose, diffusion parameters (D/α^2,E) were obtained for each meteorite by using the ^<39>(Ar)-degassing pattern which had been obtained when those meteorites had been dated by the ^<40>(Ar)-^<39>(Ar) method. The diffusion constants (D/α^2) are estimated to be (0.2-3)×(10)^<-5> s^<-1> at 1000℃. The activation energies (E) range from about 10 to 50 kcal/mole, but mostly 20 to 40 kcal/mole. Nonequilibrated chondrites seem to have lower activation energies than equilibrated chondrites. On the basis of integrated fraction of Ar, a diagram is exploited to compare relative degassing patterns of Ar between neutron induced K-derived ^<39>(Ar) and the others (^<36>(Ar), ^<37>(Ar), ^<40>(Ar)). According to the Ar-degassing patterns in this diagram, the Antarctic meteorites are classified into three Types, A, B and C. It is found that achondrites are generally classified into Type A, where ^<40>(Ar) correlates well with ^<39>(Ar) and ^<36>(Ar) (and ^<37>(Ar)) degass at slightly higher temperatures than ^<39>(Ar). Chondrites are classified into Type B, where ^<40>(Ar) correlates with ^<39>(Ar), but ^<36>(Ar) (and ^<37>(Ar)) degass at definitely higher temperatures than ^<39>(Ar). Weathered achondrites and chondrites are generally grouped into Type C, where ^<40>(Ar) does not correlate with ^<39>(Ar) and degassing patterns of ^<36>(Ar) and ^<37>(Ar) are also non-systematic. Thus, such classification would give another measure to evaluate the reliability of an ^<40>(Ar)-^<39>(Ar) age obtained in addition to conventional criteria.
- 国立極地研究所の論文
- 1984-12-00
著者
関連論文
- 40Ar-39Ar Age Studies of Four Yamato-74 Meteorites
- Pliocene and Pleistocene Volcanism in Southern Kyushu : K-Ar Ages of Fumoto and Isaku Pyroclastic Flows and Related Rocks
- K-Ar AGES OF LATE TERTIARY VOLCANIC ROCKS IN THE ASAMA AREA
- K-Ar AGE OF GLAUCONITE FROM ORIO SANDSTONE,NORTHERN KYUSYU
- K-Ar ages of alkali basalts from the Oki-Dogo island(短報)
- K-Ar Ages of Volcanic Rocks from Easter Island
- 40Ar-39Ar analyses of an Antarctic meteorite Yamato-791197 of probable lunar origin
- K-Ar AGES OF VOLCANIC ROCKS FROM THE NORTHERN AREA OF THE YATSUGATAKE VOLCANIC CHAIN, CENTRAL JAPAN
- Investigation of the effect of shock on the Antarctic meteorites by the 40Ar-39Ar method
- 40Ar-39Ar analyses of lunar anorthositic breccia, Yamato-82192 from Antarctica
- K-Ar Ages of a basanitoid lava flow of Nanzaki Volcano and underlying Miocene andesites from the Irozaki area,Izu Peninsula central Japan(短報)
- The Use of Obsidian for K-Ar Dating
- Characterization of Ar-degassing from Antarctic meteorites
- 40Ar-39Ar Ages of L and LL Chondrites from Allan Hills, Antarctica: ALHA77015,77214 AND 77304