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Volume 52, Issue 1
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Sachio Orimoto1964 Volume 52 Issue 1 Pages 1-10
Published: July 05, 1964
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSIn the Nakanomata prospecting area, Yamagata Prefecture, an igneous complex intrudes into the strata that are composed of the pyroclastic rocks and the lava flows in the lower Miocene.
The pyroclastic rocks are divided into two parts; andesitic lapilli tuff_??_tuff breccia at the lower part and dacitic lapilli tuff_??_tuff breccia or volcanic breccia at the upper part. The upper part is characterized by welded tuff. The pyroclastic rocks might accumlate on land as the pyroclastic flow.
The main rock facies of the igneous complex may be named as gabbro, diorite, granodiorite, andesite and dacite.
Fissure patterns are vertical or parallel to the general trend of the geological structure in this area, and the veins which have been prospected occure filling the former. Ore minerals are pyrite, sphalerite, galena and chalcopyrite, and gangue minerals are quartz, calcite and chlorite.
In this paper, the problem if the so-called Tertiary granitic masses including this complex in northeastern Japan are products as the plutonism or as the volcanism is proposed.View full abstractDownload PDF (590K) -
MASATAKA ENDO1964 Volume 52 Issue 1 Pages 11-22
Published: July 05, 1964
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSSixty sphalerite samples were collected from various mines in Japan. Ore deposits of Oe (Hokkaido), Toyoha (Hokkaido), Namariyama (Akita Prefecture), Nikkatsu (Akita Pref.) and Kuroiwa mines (Fukushima Pref.) are vein type deposits, those of Hanawa (Akita Pref.), Yoshino (Yamagata Pref) Yonaihata (Fukushima Pref.) and Kidogasawa (Tochigi Pref.) mines are so-called Kuroko type deposits, while Hitachi mine is a Kieslager type deposit.
From the results of chemical analyses and X-ray measurements on sixty sphalerite samples, it has been recognized that natural β ZnS minerals consist of the β1 sphalerite and β2 sphalerite.
The unit cell edges in β1 sphalerites are determined by Fe, Mn and Cd content dissolved in this minerals, and the equations of relation between unit cell edges and FeS content in this minerals are shown a0=5.4103+0.000717 X and a0=5.4124+0.000349X. a0 is in Angstrom unit and X is mole % FeS, and both these equations are continuous.
The solubility of Mn in β1 sphalerite increase with an increasing FeS content, so that it is a function of the temperature and pressure as well as the variation of FeS content. The correlation between Fe and Cd is random, but the variation of Cd solubility is constant.
From the variations of Fe, Mn and Cd content, β1 ZnS system is divided into β1 (Zn, Fe, Cd)S and β1 (Sn, Fe, Mn)S system.
Also the equation of β2 sphalerite is shown by a0=5.4093+0.000290X.View full abstractDownload PDF (649K) -
Fumimori Tsushima, Kazuo Miyagi1964 Volume 52 Issue 1 Pages 23-32
Published: July 05, 1964
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe volcanic rocks of the “Sôma formation” (Miocene in Age) of the western margin of Hirosaki Basin, Northeast Japan were petrologically studied by writers.
They are chiefly composed of andestic tuff breccia (or volcanic breccia), andesitic (driblet) agglomerate and lave flows of augite hypersthene basaltic andesite, hornblende hypersthene augite andesite, biotite hypersthene augite dacite and hornblende rhyolite. All rocks belong to the calc-alkalic rock series derived from the high-alumina basalt magma.
Eight representative rocks are chemically analysed. They are characterized by high in Al2O3 and K2O than those of the Neogene volcanic rocks belong to calc-alkalic rock series and tholeiitic rock series in other region of Northeast Japan.View full abstractDownload PDF (527K) -
Kazumi Doi1964 Volume 52 Issue 1 Pages 33-38
Published: July 05, 1964
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThis work is a test for the application of radioactive survey to geological survey in field. This survey is applied to the contact metamorphic rocks which occured by the granite intrusion into the paleozoic formation in Onnagawa district of northern part of Niigata Prefecture. The radioactivity of this metamorphic rocks are determined by the contents of potash feldspar in the rocks. Potash feldspar occurs in nearest part from granite intrusion, which are most strongly metamorphosed.View full abstractDownload PDF (275K)
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