Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
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Special Issue
Volume 72, Issue 8
Displaying 1-3 of 3 articles from this issue
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  • Vertical Variation of Rhenium, Cadmium, Silver and Platinum-group Elements within a Transitional Bed of Danish Cretaceous-Tertiary Boundary Layer
    Takahiro SHIOKAWA, Yu Vin Yi SAHOO, R. GANAPATHY, Akimasa MASUDA
    1996 Volume 72 Issue 8 Pages 163-167
    Published: 1996
    Released on J-STAGE: October 17, 2006
    DOIhttps://doi.org/10.2183/pjab.72.163
    JOURNAL FREE ACCESS
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    Contents of Re, Cd, Ag and platinum-group elements in specimens from four sub-zones of a 3cm-thick bed of a K-T boundary layer from Stevns Klint in Denmark, were determined by stable isotope dilution using ICP mass spectrometer. The chondrite-normalized Re value linearly decreases in the upper zone. Also the content of Ag linearly diminishes upward. These relations lead us to a conclusion that, at the earliest stage of the formation of this bed, the marine site studied was hi ghlyreducing, and at the final stage of the bed formation, the sea recovered to the “normal” oxidation-reduction potential. That is, it is reasoned that the anomalously reducing condition at the site persisted for a relatively short period. Some discussions are given to effect of chemical valency state on distributional features and to fractionation in the dust fallout.
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  • Importance of Compression Melting in Subduction Zones
    Hikaru IWAMORI
    1996 Volume 72 Issue 8 Pages 168-173
    Published: 1996
    Released on J-STAGE: October 17, 2006
    DOIhttps://doi.org/10.2183/pjab.72.168
    JOURNAL FREE ACCESS
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    Processes of melt generation in subduction zones are discussed, based on numerical calculations taking account of the flow pattern, energy balance and phase equilibrium constraints for H2O-bearing peridotites. A significant amount of melt is newly found to be produced in the downward flow along the plate by compression melting, corresponding to a gentle or negative dT/dP slope of the solidus curve. The amount of melt produced is comparable to the eruption rate of magmas on volcanic arcs (i.e., 100 to 102km3/million year per 1km of the arc length). Although further studies on the distribution of H2O and melt segregation processes are required for accurate estimates, compression melting in subduction zones is probably inevitable.
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  • Stereoselective Synthesis of Lurlenic Acid and Lurlenol, the Sex Pheromones of the Green Flagellate Chlamydomonas
    Kenji MORI, Shin-ichi TAKANASHI
    1996 Volume 72 Issue 8 Pages 174-177
    Published: 1996
    Released on J-STAGE: October 17, 2006
    DOIhttps://doi.org/10.2183/pjab.72.174
    JOURNAL FREE ACCESS
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    Lurlenicacid[(4E, 8E, 12E)-14-[2'-hydroxy-3', 4'-dimethyl-5'-(1"-β-D-xylopyranosyloxy) phenyl]-4, 8, 12-trimethyltetradeca-4, 8, 12-trienoic acid, 1] and lurlenol (2), the sex pheromones produced by the female gametes of the green flagellate Chlamydomonas, were synthesized stereoselectively.
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