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Volume 72, Issue 6
Displaying 1-5 of 5 articles from this issue
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THE ULTIMATELY FORMED APHANITIC DIABASETakeo Bamba1977 Volume 72 Issue 6 Pages 221-226
Published: June 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe Shimokawa diabase complex is mainly composed of coarse-grained and finegrained facies of ophitic textured diabase being partially associated with variolitic diabase characterized by the presence of well-pillowed structure.
Recently, the present author percieved the small scale unpillowed aphanitic diabase intruded into the ophitic diabase at S-50 of L-10 level in a gallery of the Shimokawa Mine. This aphanitic diabase in question was exmained petrographycally and it was clarified that the rock properties of the aphanitic diabase is just equivalent to the pillowed one.
The chemistry of the Shimokawa diabase complex indicates that the rock is wholly tholeiitic though various facies ranging from ophitic to aphanitic is distinguishable.
Following is the author's consideration on the origin of the Shimokawa diabase complex:
The Shimokawa diabase of initial phase is represented by the coarse-grained ophitic facies which might have been formed through the hypabyssal condition, then the intrusive niveau of the successive diabase might have been in turn upheaved, and fine-grained ophitic facies should be formed. The intrusive niveau of the Shimokawa diabase have been ultimately changed as far as nearly subaerial and the aphanitic diabase might have been formed.View full abstractDownload PDF (2353K) -
Ko IKEDA1977 Volume 72 Issue 6 Pages 227-240
Published: June 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSPhase equilibria in the join CaCaSiO4-CaCrCrO4 were investigated by the quenching technique. Although the maximum solubility of CaCrCrO4-component to calcium orthosilicate was not determined because of experimental difficulties, it is estimated to be less than 9 wt percent for α form. The solbility in α form is 8.1 wt percent as much at 1500°C and that in α' form is 1.9 wt percent as much at 1100°C. In the moderate temperature region there is α wide range of coexisting region of α form and α' form. Calcium orthosilicate solid solutions are quenched usually as β forms. However, high temperature modification of α form is preserved to room temperature partly or almost entirely, when CaCrCrO4 content exceeds 4 wt percent. The crystalline phases are α calcium orthosilicate solid solution, α' calcium orthosilicate solid solution and β calcium chromite in the investigated temperature. The calcium orthosilicate solid solutions of α form and β form after α form are green in colour, while those of β form after α' form are bluish green in colour. Subsequent measurement of optical spectra for the Cr-bearing calcium orthosilicate was made in wavelength range of 325-2600 nm. Crystal-field interpretation shows that Δt and B are ranging in 13800-13920cm-1 and in 460-464cm-1 for β forms, respectively, and are 13710cm-1 and 457cm-1 for α form, respectively. Assignment of bands indicates that tetrahedral Cr3+ ions may be present in low spin state as suggested by Ikeda and Yagi (1977) for Crbearing blue diopsides.View full abstractDownload PDF (1658K) -
MAKOTO YUASA, TERUO WATANABE1977 Volume 72 Issue 6 Pages 241-251
Published: June 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESS -
YUZO KATO, HITOSHI ONUKI, HISAO TANAKA1977 Volume 72 Issue 6 Pages 252-258
Published: June 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSFive pairs of biotite and hornblende from the rocks of the Senmaya granitic intrusion in the southern Kitakami Mountains were analysed chemically. The apparent distribution coefficient of Mg-Fe2+ between biotite and hornblende is considerably controlled by the My/Fe2+ ratio as well as the AlIV content of hornblende in calc-alkaline granitic rocks from Senmaya district and other various localities in the world.
With regard to the chemistry of hornblende coexisting with biotite in granitic rocks, the following facts are established: The relation between the Mg/Fe2+ ratio and any one of the AlIV, (Na+K), (AlVI+Fe3+) and Ti contents shows a good linearlity with a negative gradient; the difference in magnitude between the AlIV and (Na+K+AlVI+Fe3++Ti) contents is ascribed to the effects of the glaucophane-riebeckite and/or richterite substitutions.View full abstractDownload PDF (264K) -
Haruo Ohashi1977 Volume 72 Issue 6 Pages 259-262
Published: June 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSEuhedral crystals of NaCrSi2O6 solid solution have been synthesized by solid state reaction at high pressure and temperature. The size of crystals is about 100μlont. The shape is elongate to C axis as much as the composition of crystals is rich in NaCrSi2O6 component.View full abstractDownload PDF (1920K)
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