The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 61, Issue 723
Displaying 1-6 of 6 articles from this issue
  • Takao YAMAGUCHI
    1955 Volume 61 Issue 723 Pages 559-565
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    The cleavage plan which is often mistaken the bedding plane must be distinguished from the latter., With such purpore the following study was made., 1., The orientation of the bedding plane and the cleavage plane should be measured statistically according to the small samples theory., 2., On a Schmidt's net, the poles of the cleavage planes distribute always along a large circle in the form of normal distribution, while those of the bedding planes do not., 3., Such a distribution of the cleavage planes is similar to that of joints., Therefore, in the same way as in the case of joints (Fig., 6), the direction and the plane of the differential movement which caused the cleavage can be found., 4., The factors in the case of schistosity plane are similar to those in the case of cleavage plane., The direction of the lineation of one green schist was found to be oblique to the direction of the differential movement of the rock deformation during dynamo metamorphism., 5., The structural analysis in such a way is a very interesting and important study for sedimentation, structural geology, metamorphism, etc.,
    Download PDF (713K)
  • Kiyosi KOIKE
    1955 Volume 61 Issue 723 Pages 566-582
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    Of the many types of inter-formational disturbances, the mudflow type is discussed here., The major area in which investigation was undertaken is the vicinity of southern Kanto, and various parts of Japan are also considered., The following are summarized as the conclusion: 1) The mudflows are the products of intense crustal movements, which are supposed to be more frequent in the earliest and the latest stages of the development of a single group consisting of sedimentary formations., 2) The characteristic feature of these mudflows is the contamination of coarse sediments into finer fractions., 3) The mudflows are variously modified by certain geological features: e., g., tectonic framework, sedimentary environments etc., The angle of the slope to initiate the mudflows might be in the range of 3 to 10 degrees., 4) The condition necessary to stabilize the sediments after the mudflows is the existence of a flowing water mass succeeded by a stagnant condition.,
    Download PDF (2173K)
  • Yoshiaki SATO
    1955 Volume 61 Issue 723 Pages 583-588
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    There are developed strata of conglomerate, sandstone, and mudstone of Oligo-Miocene to Lower Miocene ages in the Chichibu basin., The Akahira formation, one of the Tertiary formations, unconformably overlies the pre-Tertiary sedimentary rocks in the northern and western margins of the basin., The purpose of this paper is to differentiate the heavy minerals included in the lowest part of the formation, and to investigate the source rocks of the sediments., The results obtained are as follows: 1., In the northern part of the basin, fairly large euhedral or angular crystals of allanite, anatase, biotite, epidote, garnet, titanite, tourmaline, zircon, augite, and hypersthene are commonly found., Green and brown hornblende, topaz, barite, and olivine are found in only a few samples., On the other hand, only few rounded garnet, titanite, zircon, and some other minerals are found in the western part., 2., It is possibly said that the sediments in the northern marginal part were derived not only from pre-Tertiary sedimentary rocks but also from granitic and basic igneous rocks., 3., The texture of the heavy minerals indicates that the source area of the granitic rocks might not be far from the basin., 4., There is no evidence that the sediments were derived from the Nagatoro system which consists of crystalline schist.,
    Download PDF (672K)
  • Ryohei TAKAHASHI
    1955 Volume 61 Issue 723 Pages 589-597
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
  • Tokio SHIKAMA
    1955 Volume 61 Issue 723 Pages 598
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    Download PDF (299K)
  • Atushi HORII
    1955 Volume 61 Issue 723 Pages 599-600
    Published: December 25, 1955
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    Download PDF (772K)
feedback
Top