The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 59 , Issue 688
Showing 1-4 articles out of 4 articles from the selected issue
  • Asahiko SUGAKI
    1953 Volume 59 Issue 688 Pages 1-14
    Published: January 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    In this paper, genesis of some lattice textures of ore minerals is discussed., The studies have been made by many authorities on the lattice intergrowth formed by unmixing of a solid solution, which has been primarily deposited from the fluidal solutions., However, no considoration has been made on the exsolution from the secondary solid solution, which has been produced by mutual diffusion between solid minerals., The writer has experimentaly confirmed the unmixing phenomena of the secondary solid solution as follows; 1) Some solute minerals, such as massive chalcopyrite, vein-like chalcocite or covellite, drop-like klaprothite and massive tetrahedrite, diffuse in host minerals, such as bornite, at high temrperatures from 400°C to 500°C and form the various solid solution 2) The solid solutions, thus obtained, can unmix upon annealing at low temperatures of about 200°C and give some exsolution textures, such as lattice, cell and emulsion ete., The phenomena, as described above, may be expected to occur in such geological cases when some earlier minerals suffer higher temperature at later stage of mineralization or the ore bodies receive the thermal effect by igneous action., From this point of view, more attention must be given on the ore textures formed by thermal metamorphism., Explanation of Plate 1) Lattice intergrowth of chalcopyrite (light gray line) in bornite (Bo) from the Ginmu mine, Hiroshima Prefrcture., Ch, massive chalcopyrite., ×95., 2) Chalcopyrite (light gray line) lamellae unmixed from the secondary solid solution, formed by Solid diffusion between bornite (Bo) and massive chalcopyrite (Ch) at 500°C for one hour, by keeping at 200°C during 17 hours., ×95., 3) Lamellea, semi-cells, worm-like and dot-like bodies of Chalcopyrite (light gray line and spot), obtained under the same conditions as in 2)., Bo, bornite; Ch, massive chalcopyrite., ×95., 4) Chalcopyrite (ch) in lamellae, semi-cells and worm-like crystals, produced by annealing the secondary solid solution, same as before, at 200°C for 16 hours., Bo, primary bornite; bo, secondary bornite formed by thermal decomposition of massive chalcopyrite (Ch)., ×95., 5) Secondary covellite (Co) replaced the bornite (Bo) from the obari mine., Ch and Kl, chalcopyrite and klaprothite lamellae unmixed from the primary solid solution respectively., ×95., Etched with KCN., 6) Crystallographic itatergrowth of bornite (light gray) and chalcocite (dark gray) obtained by slowly cooling the secondary solid solution, formed by solid reaction of bornite and secondary covellite, as showed in 5), under heating condition of 440°C for one hour., Annealing condition, from 300°C to 200°C for 7 hours., Py, pyrite produced by thermal decomposition of bornite., ×300., Etched with KCN., 7) Pyrite (Py) produced by thermal decomposition of bornite at 440°C for one hour., Be, fine lattice intergrowth of bornite and chalcocite, obtained by unmixing of the solid solution under the same condition as in 6)., ×95., Etched with KCN., 8) Myrmekitic texture formed by solid diffusion between bornite (dark gray) and wittichenite (light gray) at 400°C during 20 hours., ×300.,
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  • Sunao OGOSE
    1953 Volume 59 Issue 688 Pages 15-24
    Published: January 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    During the writer's study on the Mizunami group developed in the environs of Mizunami-Toki-mati, Toki-gun, Gihu-prefecture, he entertained some doubts concerning the fundamental geological conception hitherto been generally accepted by Japanese geologists., In order to solve a part of the doubts, the writer has considered in this paper the following three problems:(1) Significance of fossils as an indicater of "sedimentary environment" of strata, (2) Significance of fossils as an indicater of geological age of strata, (3) Meaning of fossil-facies as one of factors defining lithofacies., These are all interesting and important problems concerning fossil-stratigraphy and biochronology laid in the recent Japanese geologists., The fundamental geological conception hitherto been adopted is standing on a point of view that fossil-stratigraphy is synonymous with biochronology, while in the writer's present opinion these two are to be separated distinctly from each other., Then, the term "biostratigraphy" hitherto generally been used by almost all geologists should be abandoned., It must be done, however, under the world-wide discussion in future., The writer expects that this paper is a reference on the occasion of such a discussion.,
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  • Yukinori FUJITA, Kunio SUYAMA
    1953 Volume 59 Issue 688 Pages 25-31
    Published: January 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Wir haben die Ursache der Verschiedenheit der Machtigkeit der Formation untersucht, und uber den Ablagerungsmgechanismus zu einem Schluss gelangen., Die vulkanische Tatigkeit, welche schon am Ende der Toyooka-Zeit angefangt war, ist hochst lebhaft in der zeit hinduch die Kurotaki-Tuff-Formation., Dabei begleitet die vulkanische Tatigkeit die Bruchbewegung in ganzen Gebiet der Ablagerungsbezirke am Ende der Toyooka-Zeit, und bracht die asymmetrisch Sinkung in demselben Gebiet seit der Kurotaki-Zeit., Kurz gesagt, ist die Ablagerungsbezirke im Osten immer tiefer gesunken als im westen und mehr machtiegere Shitchten waren im Osten bei jeden Formationen von der Kurotaki-Tuff-Formation on bis zur Kiwado-Formation als im westen abgelagert., Wir glauben, da solche asymmetrische Sinkung auch zu Geologischen Strukturen der alteren Formation wie Toyooka-Untergruppe beeinflusst, m., a., w., die Faltung die in der Toyooka-Unter-gruppe beobachtet, ergibt sich wenigstens zum Teil durch die asymmetrische Sinkung der Seki-Untergruppe.,
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  • Yasuhiko KAMADA
    1953 Volume 59 Issue 688 Pages 32
    Published: January 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
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