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Volume 76, Issue 11
Displaying 1-5 of 5 articles from this issue
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MICHIO TAGIRI1981 Volume 76 Issue 11 Pages 345-352
Published: November 05, 1981
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSA separation-method for dispersed carbonaceous material in rocks and a calculation-method for Lc(002) are presented, and a numerical expression of the graphitizing-degree is newly proposed revising Tagiri and Tsuboi (1979), Graphitizing-degree=[(d002-3.70)/log (Lc(002)/1000)]×100. Some examples in the metamorphic aureoles are indicated and it has been clearly shown that the graphitization mainly depends on temperature suffered and that it is useful to investigate a geothermal structure.View full abstractDownload PDF (640K) -
Shuichiro Koga1981 Volume 76 Issue 11 Pages 353-361
Published: November 05, 1981
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSYabakei pyroclastic flow deposits (YPF), which have been developed in middle Kyushu, especially in Oita prefecture, are described and discussed about two outcrops (Y1, Y2) petrographically and petrochemically. YPF cover over 300km2 and their volume is estimated about 25km3. This pyroclastic flow deposits range from augite-hypersthene-hornblende andesite to dacite under the microscopic observation and chemical analysis. YPF are divided into two parts according to their chemical compositions and the degree of welding. The welded part is gradually transitional to that of no welding but some variations in the following chemical compositions (such as SiO2, Na2O and Al2O3) are recognized. This would be caused mainly by the selective leaching of volcanic glass toward the part of no welding. And it is recognized that it exists negative relation between Na2O and H2O (+). This fact may support that selective leaching of volcanic glass in the same part of no welding (Y2).View full abstractDownload PDF (1456K) -
AKIRA FUJIYOSHI, KYOICHI ISHIZAKA, ICHIKAZU HAYASE1981 Volume 76 Issue 11 Pages 362-367
Published: November 05, 1981
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe metamorphic rocks regarded as Precambrian are widely exposed in the Tarma area of the central cordillera, central Peru.
Discordant Rb-Sr ages of 230 and 147m. y. on biotite were obtained from a sillimanite-biotite migmatitic gneiss and a garnet porphyrobast biotite schist, respectively, in the metamorphic mass of the area. The presence of the retrogressive imprint observed in the gneiss suggests that the older age is a minimum one of the regional metamorphism in the area. It also suggests that a main phase of its metamorphism belongs to an upper Paleozoic orogeny revealed by Rb-Sr whole-isochron ages from a Chilean metamorphic basement.
The younger age might indicate the effect of a late Jurassic-early Cretaceous platonic mass or a tectonic event of this time.View full abstractDownload PDF (460K) -
HARUO OHASHI, TOSHIKAZU OSAWA1981 Volume 76 Issue 11 Pages 368-371
Published: November 05, 1981
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSInfrared spectra of In2Si2O7 and Lu2Si2O7 with thortveitite structure were measured in the frequency range 1300-400cm-1. The frequencies of the anti-symmetrical Si-O-Si stretching in In2Si2O7 and Lu2Si2O7 are 1175cm-1, and 1115cm-1, respectively. The frequency in M3+2Si2O7 compound with thortveitite structure is strongly influenced by the electronegativity and the electronic structure of the M3+ ion. These facts suggest that the Si-O (br) distance in thortveitite structure is strongly influenced by them.View full abstractDownload PDF (255K) -
AWARUITE AND OTHER ACCESSORY MINERALS COEXISTING WITH Ti-RICH HYDROANDRADITE IN METAMORPHOSED ULTRAMAFICS OF THE SANBAGAWA BELTHITOSHI ONUKI, TAKEYOSHI YOSHIDA, MUNETOMO NEDACHI1981 Volume 76 Issue 11 Pages 372-375
Published: November 05, 1981
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESS
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