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Volume 59, Issue 696
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Tatsuo YAMASAKI1953 Volume 59 Issue 696 Pages 403-419
Published: September 25, 1953
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSFor the classification of the Palaeogene strata in the Karatsu coal field in northwest Kyushu, a scheme was first proposed by T., MAGAO (1926) and has since been adopted by many geologists., The criterion for the classification, however, was not clearly stated by Nagao and the variations in lithologic facies were not fully described for the entire field., A review of NAGAO's classification is presented because the author found that by checking the key beds, for example tuffaceous rocks, conglomerates, and fossiliferous zones, which are easily traceable throughout the field, a change in the lithologic facies from northeast to southwest, could be mapped in some formations., The relationships are summarized in figure 2., a generalized scheme of the revised stratigraphy is shown in table 1, and the range or fossils, with reference to the revised classification, is shown in table 2., The problem of the Eocene-Oligocene contact in this coal field is described., Furthermore, the geological history is briefly discussed and special reference is made to a crustal movement near the end of the Ashiya age., The movement caused a shift in the location of the basin which was receiving sediments.,View full abstractDownload PDF (2004K) -
Y. FUJITA, K. KOIKE1953 Volume 59 Issue 696 Pages 420-423
Published: September 25, 1953
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSIn this paper the stratum that is seen in the Shiogama District is divided into three parts; the Shiogama, the Hamada, and the Matsushima formations., There was found Desmoslylus in the upper part of the Hamada formation., The writers intended to determine the age of the formations by studying the fossils found there, and presumed them to l e of middle Miocene.,View full abstractDownload PDF (618K) -
Gensei YOSHINO, George KOJIMA1953 Volume 59 Issue 696 Pages 424-434
Published: September 25, 1953
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe Ehime mine is situated about 5., 5km to the south of Niihama., Crystalline schists of the Sambagawa Group outcrop in the district., The crystalline schists of the district are composed of black-schists, originated from argillaceous rocks, sandstone-schists, derived from arenaceous rocks, siliceous schists from quartzose rocks, and green-schists, accompanied by serpentinite., The schistosity planes generally coincide with the original planes of stratification, and they dip mainly to the north., The crystalline schists can be divided litbologically into four formations, as tabulated below in the seemingly descending order., Formation Component rocks S Sandstone-schist and black-schist, interbedded with thin beds of green-schist and siliceous schist., R Black-schist, sandstone-schist, and five beds of conspicuous green-schist with siliceous schist., Q Mainly composed of black-schist., P Thick beds of green-schist, intercalated with thin beds of black-schist and siliceous schist., Structurally, areas may be divided into several blocks, among which the block composed of formation P, and the block formed by formations R and S, are discontinuous., The former belongs to the northern wing of the Sasagamine-Kampuzan anticline, while the latter is the block thrust over the former from the north., Formation Q should be interpreted as the shear zone between these two blocks., The Ehime ore body is deposited in the lowest part of the overthrust mass and is conformable to the foliation planes of the siliceous schist, which extends E-W., Albite porphyroblasts or spots are generally developed in formations R and S, but the spots are not uniform in size throughout the block., The heterogeneous development of spots might have been related to the heterogeneity of the original rock and differences in the amount of deformation., The albitization related to the formation of albite spots was controlled by the modes of deformation and by tectonic transport of the different parts of the deforming block at some stage in the process of the metamorphism of the crystalline schists., Albite spots were enriched in the parts of least componental differential movement., Metasomatizing agents moved through the passage which was formed in the parts of strong componental differential movement.,View full abstractDownload PDF (1376K) -
Kenji K0NISHI1953 Volume 59 Issue 696 Pages 435-436
Published: September 25, 1953
Released on J-STAGE: April 11, 2008
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Takeo BAMBA1953 Volume 59 Issue 696 Pages 437-445
Published: September 25, 1953
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSHigashi Akaishi-yama, which is composed of dunite, is situated in the Sambagawa metamorphic zone in the northern part of Shikoku., Structurally, the dunito mass can be divided into eastern and western parts, and the constituent rocks of each part are different., The eastern mass is composed of spinel bearing dunite, pyroxene peridotite, eclogite and chromite ore with a well defined banded texture., Spinel crystals, as an accessory component of the dunite facies in the eastern mass always contain much chromite, usually about 40% Cr2O3 by weight., The western mass is composed of spinel bearing dunite and pyroxene peridotite, but neither eclogites nor banded chromite ore have been found in it., The spinel crystals in the western mass contain very little Cr2O3, at the most about 16% by weight., Comparison of the chemical composition of the chromite crystals in 'the banded ore with the chromite crystals in the country rock show, the weight percent of the Cr2O3 in the ore to be 50% more or less, and that of the country rocks is usually 40% or less., It is believed that the accumulation of the chromite crystals has had influence on their own chemical composition.,View full abstractDownload PDF (1664K)
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