The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 60 , Issue 701
Showing 1-4 articles out of 4 articles from the selected issue
  • Kiyoshi ASANO
    1954 Volume 60 Issue 701 Pages 43-49
    Published: February 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Previous studies of age determination and correlation of the Poronai shale in the Ishikari Coal field, Hokkaido were based almost entirely on megafossils., The presence of numerous foraminiferal species has been reported by the writer, but the general foraminiferal sequence has not yet been disscussed., In this paper, the writer divides the whole sequence into 4 zonules., The lowest Ammobaculites zonule crops out in the Hobetsu area, but the uppermost Plectofrondicularia zonule is distributed from the Ikushunbetsu to the Nokanan area., This suggests that the transgression of the sea which deposited the Poronai progressed from south to north., The Foraminifera from the Wakkanabe formation in the Akabira area consists of characteristic species of the Ammobaculites zonule., It shows that the sea which deposited the Wakkanabe can not be separated from the earlier Poronai sea, and the writer names the whole sea as Paleo-Ishikari Sea., The age of the foraminiferal sequence of the sea is considered to be from Upper Eocene to Lower Oligocene, and is correlated with those of the Cowlitz, Keasey, and Lincoln in Washington., U., S., A.,
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  • Shingo EHARA
    1954 Volume 60 Issue 701 Pages 50-66
    Published: February 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
  • Toshio KIMURA
    1954 Volume 60 Issue 701 Pages 67-80
    Published: February 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The sedimentary rocks of the upper Jurassic Nakanosawa formation were studied in this paper., They are classified into following ones., 1) A (dark gray) sandstone., This is abundant in matrix minerals and biotite flakes, and the diameters of the sand grains are small., : (Graywacke and subgraywacke after PETTIJ0HN'S classification)., 2) B (white) sandstone., : This is characterized by the large diameters of its sand grains, and contains a tew matrix mineral and biotite flake., (Orthoquartzite after PETTIJ0HN'S classification)., 3) C (calcareous) sandstone., : This yields abundant lime matrix, and its sand greins show large diameters., 4) Oolitic limestone., 5) Black, dense limestone., The B sandstone was the product under the condition of stronger water current than the A sandstone., The C sandstone and oolitic limestone were formed, when the depositional environments showed the relative increase of the deposition of lime, under rather strong water current., The relation between the volume percentage and the diameter of sand grains of the sandstones, and those of ooid of the oolitic limestone were examined, and it is concluded that the depositional condition of lime matrix of oolitic limestone was the same with that of calcareous sandstone, and sericite-like mineral as matrix of the A and B sandstone were washed away more easily than lime as matrix of the calcareous sandstone and oolitic limestone under a certain current., "Composite" ooids, composed of small simple ooids, fossil remains, and lime matrix, were formed when they rolled about on the sea bottom., The sandstones of the Tochikubo formation and the Tomisawa formation, which are overlain and underlain respectively by the Nakanosawa formation, have a good deal of feldspar grains, and the lower part of the Nakanosawa formation contains more feldspar grains than the upper part., The writer concluded that the backgrounds of the depositional basin rose before the deposition of the Tochikubo formation, and the Nakanosawa age was that of planation, and after the deposition of the Nakanosawa formation the backgrounds rose again., The limestone of the Nakanosawa formation was formed by the decrease of the deposition of terrigenous materials in the age of planation., The deposition of the lower part of the Koike limestone (the uppermost part of the Nakanosawa formation), mainly composed of oolitic limestone, was under the influence of rather strong water current, and the upper part of the lime stone, consisting of much black, dense limestone and oolitic limestone, was formed at deeper sea bottom than the lower part.,
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  • Haruhiko KIMURA
    1954 Volume 60 Issue 701 Pages 81-93
    Published: February 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    This paper mainly describes the results or experiments on "proper critical velocity" and the traction of sedimentary particles under different conditions, the theoretical relationship between proper critical velocity and settling velocity, and the geological implications of these., ("Proper critical velocity" is the mean value of velocities of currents acting at the bottom and top portions of a particle to start the movement of that particle)., Concerning the above-mentioned subject, the writer obtained the following results: (1) If the sedimentary bed has a smooth and horizontal plane, the proper critical velocity "Vp" is proportional to dn, namely, in the case of Vpr and VpII VpI=k1dnI VpII=k2d<nII> (cf., part 1), Where VpI is Vp to a single particle, VpII is Vp to the multiple particles, d is the diameter of the particle, k1·k2 and nI·nII are the constants as follows at l0°C; d<0., 14mm., ., ., k1=3700 k2=360 nI=2., 2 nII=1., 8 0., 14<d<1., 3., ., ., k1=150 k2=210 nI=1., 5 nII=1., 6 1., 3<d<6., 7 k1=35 k2=65., ., ., nI=0., 8 nII=1., 0 6., 7<d., ., ., k1=31 nI=0., 5 (2) When the particle size is fixed, Vp varies with the the density G of the particle as follows, Vp=K (G-1)β K and β are the constants, which will be given as K=1., 1 and β=O., 65, respectively, for the given size of particles, 0., 14<d<1., 3mm., However, a grain such as the fragment of a shell has a comparatively small Vp for its d and G, as it has a larger form-drag., (3) When the particle size is fixed, Vp is proportional to the roughness dr (namely the granularity of the bottom) as follows; Vp=k1dnI+(k2dnII-k1dnI) dr/d where d>dr., (4) Vp and settling velocity W are both given by the discontinuous function of d, and if d is fixed, the value of n in Vp is equal to it in W., (5) When the concentration of particles increases, Vp decreases but W increases., These results are important as factors in determining the size distribution of sediments, and its discontinuity.,
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