The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 56, Issue 658
Displaying 1-5 of 5 articles from this issue
  • Haku Koide
    1950 Volume 56 Issue 658 Pages 351-359
    Published: October 05, 1950
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    There are many veins in rocks, especially in the metamorphics including secondary altered rocks due to chloritisation and sericitisation., Quartz-vein, calcite-vein, aplitic vein, pegmatitic vein, epidote-vein, biotite-vein, sericite-vein and the so-called "ore-vein" are common., This paper deals with the general modes of occurrence of the various veins, from which the theory of the origin and genesis of them are concluded as follows : Up to this time, veins are generally treated as the foreign materials intruded into the country rocks from the outside sources, for example from the igneous rocks exposed near and around the country rocks, in the form of "solutions" like "silica or siliceous solution" in the case of quartzvein., It seems, however, to be difficult to explain the modes of occurrence of the veins by this theory., It is not neccessary, at least, to follow the theory with regards to the origin and genesis of the veins., Based on the facts described in this paper, there seems to be no doubt that almost all of them are seggregation veins., Quartz, calcite and the other minerals gather from the country rocks themselves through metamorphic differentiation under the physico-chemical condition represented by certain "emanation" and appear as seggregation veins., The writer will discuss briefly the problem, taking "ore-veins" as an example., In the "ore-veins" such as quartz-copper-vein and calcite-copper-vein, the quartz and calcite are called as "gang minerals, " which are introduced into the country rocks from certain outside sources and carry the useful metalic ores or rather metallic elements., But it is not neccessary to consider the quartz and calcite as the foreign materials introduced into the country rocks in the form of "ore solutions., " According to the writer's opinion, they are squeezed out from the country rocks themselves, which are always altered to the chloritised and sericitised rocks in certain degree., Silica and lime are isolated from the rocks through the process of chloritisation and sericitisation, both of which are probably caused by the emanation of water, sulphur, carbon dioxide (or rather carbon monoxide), etc., called as "mineralised gas., " This free silica and lime appear as seggregation veins of quartz and calcite with or without the usefull metalic ores., It is, of course, very difficult to make clear the reason and mechanism of the seggregation of these minerals or rather elements., But on the other hand, there are many geological facts suggesting that the common rock-forming elements are roughly divided into two groups ; the one having a remarkable geochemical character with a strong tendency to make gathering as the pure mass and the other having geochemical character to disperse widely in the rocks., In this paper, the former group is geochemically called as "seggregation elements" and the latter as "dispersion elements"., Silica, lime, iron, carbon and probably alumina are the good examples of the "seggregation elements" and they strongly tend to seggregate under almost all of the geochemical conditions, even in the geochemical and geophysical environment of the surface of earth of present day., It seems to be very important that the elements which often appear as veins are almost always consisted of the "seggregation elements., "
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  • [in Japanese], [in Japanese]
    1950 Volume 56 Issue 658 Pages 360
    Published: October 05, 1950
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
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  • George Kojima, Chiharu Mitsuno
    1950 Volume 56 Issue 658 Pages 361-367
    Published: October 05, 1950
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    1) G., Kojima (1950) divided the so-called Sambagawa crystalline schists complex of the central part of Shikoku into the Nishiya Group (the lower) and the Yoshinogawa Group (the upper), and named the clino-unconformity between them Minamihiura unconformity., The Oboke sand-stone-schist beds belong to the lower part of Yoshinogawa Group., 2) About 40 pebbles were collected from the conglomerate-schists occurring in the Oboke sandstone-schist beds., They are classified according to the original rock-species as follows : -1) granite, 2) granite-aplite, 3) fine-grained biotite-quartz-diorite, 4) granite-porphyry, 5) quartz-porphyry, 6) qsuartz-porphyrite, 7) porphyrite, 8) andesite, 9) qsuartzite, 10) sandstone, 11) clayslate, and 12) basic igneous rocks, the original rock-species of which cannot be known precisely, Among them, 4) and 5) cover more than 90% of all pebbles, 3) The relic clastic minerals in the Oboke sandstone-schists were also examined., Quartz and plagioclse are present in all sandstone-schists ; orthoclase, microcline, and augite are common ; brown or green common hornblende, tourmaline (brownish), garnet, allanite, epidote, titanite, and zircon are sporadic., The areal distribution of the characteristic clastic minerals is shown in Fig., 1., The lower part of the sandstone-schist beds and the northern region are characterized by augite, while the upper part and the southern region by tourmaline., 4) The pebbles 7) to 11), and augite and saussuritized basic plagioclase may have been derived from rocks of the Nishiiya Group, which are composed of crystalline schists derived from basic igneous and pyroclastic rocks, clay-slates, sandstone, and siliceous rocks., The pebbled 1) to 6), and quartz, orthoclase, microcline, sodic plagioclase, allanite, garnet, and tourmaline indicate that acid igneous rocks were exposed on the surface when the conglomerates and sandstones were laid down., Judging from the petrographical characteristics of these acid igneous rocks, they may have been intruded into the shallower zone of earth's crust or extruded on the surface, The direct relation between these acid igneous rocks and the Nishiiya Group cannot be known, but the writers believe that the forme was intruded into the latter.,
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  • Masae Omori, Koji Suzuki
    1950 Volume 56 Issue 658 Pages 369-378
    Published: October 05, 1950
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    As a rusult of the writers, surbey, the so-called "Taga Series" developed in the neighbourhood of Hitachi City, Ibaraki Pref., has been divided into the following formations : Tertiary Upper Pliocene Hatsuzaki group Lower Pliocene Taga group Hanareyama tuff member? Hitachi sandy shale member Uppermost Miocene Kawarago formation The Kawarago formation is overlain by the Hitachi sandy shale member with a clino-unconformity., The former belongs to the Uppermost Miocene, while the latter to the Lower Pliocene., As the so-called "Taga Series" is consisted of two parts different in age and structure, it becomes necessary to re-examine the stratigraphy of all the "Taga Series" in the eastern district of Abukuma Plateau.,
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  • Masao Minato
    1950 Volume 56 Issue 658 Pages 379-382
    Published: October 05, 1950
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    Millerella sp., is newly found in the fossil collection made by me formerly (1941) at Ronjazu, near Minchen, Kirin, South Manchuria., The fusulinid Foraminifera, now in concern was collected in association with such Brachiopods and Corals of the Lower Carboniferous type as Gigantella latissimus (Sowerby), G., manchuriensis Minato, Auloclisia sp., Siphonodendron asiatica (Yabe et Hayasaka) var., minor Minato, Lonsdaleia floriformis floriformis Martin etc., It is far from doubtful that the stratigraphical horizone of Millerella sp., of Manchuria is the Lower Carboniferous, being the equivalent of Visean and Chesterian., This newly found species of Millerella is the oldest fusulinids in Asia., It is closely related to the Chesterian species, illustrated by Zeller and shows some differences from the Pensylvanian species described by Thompson.,
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