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Volume 70, Issue 10
Displaying 1-5 of 5 articles from this issue
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PART 1. PHASE RELATIONS AT 1 ATMOSPHERIC PRESSURE IN AIRKAZUO YOSHIKAWA, KOSUKE ONUMA1975 Volume 70 Issue 10 Pages 335-346
Published: October 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe phase relations in the join acmite-CaAl2SiO6 at 1 atmospheric pressure were studied and the phase diagram of the join was constructed. The solubility limit of CaAl2SiO6 in acmite is between 5 and 7wt. %. When the CaAl2SiO6 content increases, the phase assemblages below the solidus temperature in this join are changed as follows: pyroxeness (ss: solid solution), pyroxeness+nepheliness+plagioclasess, (pyroxeness+nepheliness+ plagioclasess+hematite), pyroxeness+nepheliness+plagioclasess+melilitess, nepheliness+plagioclasess+melilitess+(Ca0.6Al2O3)ss, and plagioclasess+melilitess+(CaO.6Al2O3)ss. At high temperatures pyroxeness melts incongruently to hematite and liquid. The compositions of pyroxeness in this join change from NaFeSi2O6-CaAl2SiO6 to NaFeSi2O6-CaAl2SiO6-CaFeAlSiO6 with the decrease of sodium content in the bulk composition. The bearing of this join on natural acmitic pyroxene is discussed.View full abstractDownload PDF (389K) -
HARUO OHASHI, YU HARIYA1975 Volume 70 Issue 10 Pages 347-351
Published: October 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe effect of oxygen partial pressure on the stability of CaFe3+A1SiO6 pyroxene is very large. At low oxidation conditions defined by the Fe2O3-Fe3O4 and MnO-Mn3O4 buffers, this pyroxene decomposes to form pyroxene solid solution+spinel solid solution and garnet solid solution or phase X. The essential results of our experimental study demonstrate that the proportion of the CaFe3+AlSiO6 molecule in clinopyroxenes is not a suitable geobarometric indicator but may be a sensitive indicator of P02.View full abstractDownload PDF (169K) -
YOSHIMASU KURODA, TETSURO SOZUOKI, SADAO MATSUO, SATOSHI KANISAWA1975 Volume 70 Issue 10 Pages 352-362
Published: October 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSBiotite-hornblende pairs from granitic rocks of the northern Kitakami mountaineous dristrict and of Ryoke metamorphic belt were studied for deuterium content. Some of biotites of the pairs from the northern Kitakami type had higher deuterium content than that expected for hydrogen isotope exchange equilibrium between biotite and hornblende. This was attributed to the result of exchange of hydrogen between biotite and water after the primary equilibrium was established. Biotite-hornblende pairs of Ryoke metamorphic belt exhibited a distinct disequilibrium situation with respect to deuterium content of biotite-hornblende pairs. The disequilibrium pattern of pairs could be a common feature of granitic rocks from metamorphic belts. The water initially present in magma of Ryoke granite was inferred to be greatly depleted in deuterium.View full abstractDownload PDF (363K) -
Hisahide Honma1975 Volume 70 Issue 10 Pages 363-367
Published: October 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSHematite, goethite, pyrite and others as minor minerals are recognized in the barite nodule from the Shinguri bank. Pyrite, one of above Fe minerals is estimated to be authigenic. Hematite and goethite might be formed secondary in addition with Fe ion after the formation of the nodule. And, precipitation stages of barite crystal are discussed.View full abstractDownload PDF (1992K) -
A CASE STUDY ON THE SYSTEM Ab-An-Di AT ONE ATMOSPHEREMasao Yamasaki, Shohei Banno1975 Volume 70 Issue 10 Pages 368-375
Published: October 05, 1975
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSConstruction of mathematical models of phase diagrams such as done by Barron (1972 a, b) contributes to the understanding of physicochemical processes in igneous petrogenesis.
In this review, the principles and practice of construction of mathematical models are explained in detail for the system Ab-An-Di. Major features of the ternary phase diagram can be predected from the phase diagrams of binary systems, Ab-An, An-Di and Di-Ab. Using the model we have constructed, a computer program was prepared to calculate the composition changes of major and trace elements contents in liquid and crystal phases during the maximum fractionation crystallization. The program makes it possible to calculate the fractionation curves for given starting compositions and relate it to various parameters such as percentage solidified, icophase curves, zonal structure of plagioclase, trace element partition coefficient and so on. The application of the model calculation to the natural igneous processes is also briefly discussed.View full abstractDownload PDF (327K)
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