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Volume 37 (1953)
- Issue 6 Pages 209-
- Issue 5 Pages 167-
- Issue 4 Pages 123-
- Issue 3 Pages 83-
- Issue 2 Pages 41-
- Issue 1 Pages 1-
Volume 37, Issue 2
Displaying 1-5 of 5 articles from this issue
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Kiyohiko Ishii, Yoshio Ueda, Kazuo Yamaoka, Noritoshi Yamae1953 Volume 37 Issue 2 Pages 41-51
Published: May 01, 1953
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSAccording to the field observations of Tarô district, Iwate Prefecture, it is highly probable that the volcanic complex made of andesitic rocks and their pyroclastic materials in this district have been formed at the age following the sedimentation of the Omoto formation of the basal part of the Cretaceous series, known as Ryôseki and that some of the sediments, known as Palaeozoic, seem to belong to some Mesozoic age, preceding to this formation. The granodiorites of the Miyako and the Tarô types intruded into the Harachi-yama and the Kishi formations and their pebbles are included in the Miyako formation of the upper part of the lower Cretaceous series known as Monobegawa. Therefore, the geologic age of their intrusion is believed to belong to same age between the Ryôseki and pre-Upper Monobegawa series. Also the shear zone, 1 to 25k.m. in width, passing through the Tarô-mine might have been formed in this age before granodioritic intrusion.View full abstractDownload PDF (901K) -
Studies of the Copper Ores from the Ômine Mine, Iwate Prefecture, IIIAsahiko Sugaki1953 Volume 37 Issue 2 Pages 51-58
Published: May 01, 1953
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSUnder the microscope, cubanite is found in lamellae and massive crystals in chalcopyrite from the Omine mine, Iwate Prefecture. The lamellae run parallel to ?? 111 ?? of chalcopyrite, as shown in Figs. 1 and 2, and are thought to be an unmixing product from a solid solution, while the massive crystals are believed to be a primary product from the ore solution. When both cubanite in chalcopyrite are heated in sealed tubes, the following process is observed.
1) No change is observed at temperatures from 300°C to 340°C.
2) At 350°C for 90 hours, at 400°C for 50 hours or at 450°C for from 5 to 10 hours, lamellar cubanite changes by mutual reactions with surrounding chalcopyrite into saw-toothed bodies, as shown in Fig. 3A.
3) At 400°C for 100 hours or at 500°C for from 5 to 15 hours, the cubanite lamellae suffer conspicuous diffusion from chalcopyrite, and thus converting into micrographic or lattice-shaped intergrowth of two minerals, as shown in Figs. 3B, 5 and 6.
4) A margin of massive cubanite changes by heating at 400°C for from 50 to 100 hours into irregular form the same as 2), as shown in Fig. 7.
5) At temperatures from 450°C to 500°C, pyrite appears in cubanite and chalcopyrite as granular, worm-like and dendritic crystals, as shown in Fig. 8
From the results of experiment, it is concluded that the solid solutionn of lamellar cubanite and surrounding chalcopyrite may be perfectly formed by heating at temperature of about 350°C in such long times as the geological process.View full abstractDownload PDF (2258K) -
Studies of the Copper Ores from the Ômine Mine, Iwate Prefecture IVTsunehiko Takeuchi, Asahiko Sugaki, Matsuo Nambu1953 Volume 37 Issue 2 Pages 59-65
Published: May 01, 1953
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSIt is possible to determine the paragenesis of the nine ore minerals and eleven skarn or gangue minerals in the deposit of Ômine mine by microscopic examination. On the other band, there are at least eleven kinds of unmixing intergrowth found in the metallic minerals, as has been reported previously. The unmixing temperature of them is known only in a few cases of them. Hereunder, the ouder of the 11 unmixing intergrowths, is assumed by introducing some hypotheses on unmixing, and combining the results with the paragenesis of the ore minerals determined by microscopic examination, in order to unravel the process of growth of the ores. However, there are as yet some details which require further research.View full abstractDownload PDF (506K) -
Subsurface structure of the southern margin of the Jôban Coal FieldMotoki Eguchi, Shunichi Suzuki1953 Volume 37 Issue 2 Pages 65-75
Published: May 01, 1953
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSUntil 1951, environs of the Kawaziri station of the Jôban line were thought to be the southern margin of the coal field. In the present paper the writers have proved that the southern extension of the coal seams and the coal bearing formations is not only extended in the environs of Ogitsu station but may be spreaded even to Hitachi city, Ibaraki Prefecture.
The Shiramizu group in the mapping area is directly overlain by the Tags group with marked clino-unconformnity and its outcrop is observed at Iwamoto. Moreover, the well drilled lately by C. E. A. C near Ogitsu-hama also shows the full development of the Shiramizu group excepting the Shirasaka shale formation under the Taga group.View full abstractDownload PDF (715K) -
Tsunehiko Takeuchi, Matsuo Nambu, Narundo Wada1953 Volume 37 Issue 2 Pages 75-82
Published: May 01, 1953
Released on J-STAGE: March 18, 2008
JOURNAL FREE ACCESSA variation of magnetite with particularly good parting on ?? 111 ?? (referred to as magnetite type II hereunder) has been discovered in the contact metasomatic magnetite deposit of the Kamaishi Mine.
A comparative study of this type of magnetite with the hitherto well-known massive magnetite (referred to as magnetite type I hereunder) is undertaken and has arrived at the following conclusions.
(1) Whereas the magnetite type I accompanies the earlier skarn minerals, such as diopside, hedenbergite, andradite and grossularite, magnetite type II occurred together with the later skarn minerals, such as epidote, calcite and quartz.
(2) The two types of the magnetites are indistinguishable neither by reflection microscope nor by micro-chemical tests.
(3) They both show the same Debye-Scherre ?? lines in their X-ray powder photographs (Fig. 1).
(4) Their chemical compositions are very similar, but magnetite type II contains a somewhat larger percentage of Fe2O3 than type I (Table 1).
(5) In magnetic characteristics, the coercive force is larger by magnetite type II than by type I, while the magnetic saturation value is smaller by type II than by type I (Table 2).
(6) Magnetite type II is more liable to oxidation than type I. This fact has been confirmed by the results of analysis of FeO/Fe2O3 obtained by heating magnetites of both types to various temperatures in a current of nitrogen gas with a low partial pressure of oxygen.
From the above facts, it may be concluded that magnetite II represents a fluctuation of ordinary magnetite displaced to maghemite side. It is presumed that this Magnetite type II of later crystalization has probably been crystallizcd under an atmosphere more approximating a condition favorable for oxidation.View full abstractDownload PDF (1551K)
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