The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 55 , Issue 650-651
Showing 1-12 articles out of 12 articles from the selected issue
  • Kazuo Huzita
    1950 Volume 55 Issue 650-651 Pages 199-204
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The Tertiary in the Tugawa basin, which seems to be closely connected with the oil bearing Tertiary in the Niizu nnd Kamo oil fields, includes three formations : the lower Tugawa, the middle, the Awaze, and the upper, the Tokonami., TheTugawa formation can be divided into two members : Kannonzawa conglomerate, the basal conglomerate of the Tertiary in this area, contains Comptoniphyllum-Liquidambar flora in its shaly parts, and Anadara daitokudoensis takeyamai, Paphia sp., in sandy parts; Hirotani green tuff, which has thick liparite sheets, may be correlated wuth the Takayanagi green tuff in the Kamo oil field., the Awaze formation, which has so-called "black shale" facies, overlies green tuff conformably and contains ill-preserved fossils, such as Chlamys miyatokoensis, Bursa cf., yabei, Olivella cf., iwakiensis in its lowest horizon, and Serripes laperousii, Lucinoma actilineata, behringensis, Panomga simotomensis etc., in the uppermost horizon., The greater part of teh Tokonami formation has "sandy shale" but it is difficult to distinguish from the upper part of the Awaze formation by lithological character only., Division of both formations is based upon the sight erosion surface and conglomerate between them., The above-mentioned fossils indicate that the age of the Tugawa formation is probably F2-F3, the Awaze formation is F3-G, and the greater part of the Tokonami formation is considered to belong to H (Pliocene) by lithological featers.,
    Download PDF (926K)
  • Kojiro Nakaseko, Kiyoshi Sawai
    1950 Volume 55 Issue 650-651 Pages 205-210
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The foraminiferal samples dealt with herein were collected from the control section of the Nakatsu formation exposed on the River Sagami., Microbiostratigraphically, the Nakatsu can be subdivided into two zones, the lower, the Quinqueloculina bicostata and the upper, the Rotalia sagamiensis., Many of the species from the Quinqueloculina bicostata zone, which includes five zonules, are known in shallow waters from the northern part of Japan, and this zone contains such megafossils as Umbonium arenarium, U, obsoletum and U., conglomeratum., Rotalia sagamiensis zone which includes four zonules, is characterised by the abundance of Rotalia, Nodosaria, Burimina, Bolivina, and Gyroidina, and contains many characteristic species such as Planuleria japonica, Parafrondicularia japonica, Plectofrondicularia nakatsuensis n., sp., and Robulus submamilligerus var., etc., ., Judging from the above criteria, the Lower Nakatsu is considered to have been deposited in shallow and cold waters and the Upper Nakatsu in deeper and warmer water than the Lower., The writers think that the Lower Nakatsu is the upper part of the lower Pliocene (H1b) and the Upper Nakatsu is the lower part of the middle Pliocene (H2).,
    Download PDF (820K)
  • Eitaro Takahashi
    1950 Volume 55 Issue 650-651 Pages 210
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Download PDF (267K)
  • Akiho Miyashiro
    1950 Volume 55 Issue 650-651 Pages 211-217
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    It is the purpose of the present paper to criticize the hypothesis of "stress-minerals" proposed by Alfred Harker, to make it clear that it is unneccessary to use such a concept, and to attempt the explanation of metamorphic rock characteristics by regarding temperature, pressuer (hydrostatic), and concentration of components as the only essential factors controlling metamorphism., Petrological and physico-chemical considerations do not show the necessity of Harker's hypothesis of "stress-minerals", in the present writers' view., All the minerals which Harker ranked in the category of "stress-minerals", seem to be capable of formed under some conditions without stress., They may be divided into two groups, according to the condition of generation., The first group including kyanite, staurolite, almandine, and chloritoids, may be formed only under very high pressures., They all have very high density., They occur sometimes in ignenous rocks, pegmatitic veins, hornfelses, etc., which do not show any special evidence of stress., The second group, containing chlorite, muscovite, epidote, etc., may be formed only at low temperatures., This is shown by the fact that they are hydrothermal or deuteric minerals, the temperature of whose formation is much lower than that of ordinary pyrogenetic or thermal-metamorphic minerals., Harker's "stress-minerals" seem to be such as are formed only under conditions of lower temperatures and perhaps higher pressures than in ordinary hornfelses., Each of various kinds of metamorphism, such as thermal, regional, etc., takes place under a certain definite condition of temperature and pressure., The kinds of metamorphic minerals developed are determined by the prevailing temperature and pressure as well as by the chemical composition of the metamorphosed rocks., Therefore, each kind of metamorphism is distinguished from the others by a characteristic set of metamorphic minerals.,
    Download PDF (936K)
  • Eitaro Takahashi
    1950 Volume 55 Issue 650-651 Pages 217
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Download PDF (276K)
  • Akiho Miyashiro
    1950 Volume 55 Issue 650-651 Pages 218-223
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    In this paper is given an inference as to the stability relation of kyanite, sillimanite, andalusite, and mullite., The Stability relation is represented in the figure, in which the ranges of conditions corresponding to varius mineral facies are also roughly shown., This diagram was constructed chiefly on the basis of the following facts., In such high-pressre rocks as eclogite, kyanite is commonly found but sillimanite is rare., In ordinary regional metamorphism under comparatively high pressures as shown by h, d or thereabouts in Fig., 1, kyanite is formed at lower temperatures, and sillimanite at higher., In some cases of regional metamorphism where the pressures prevailing are relatively low as shown by s or therebouts in the diagram, andalusite also occurs., In thermal metamorphism under even low pressures s, r or still low in Fig., 1, andalusite is most commonly found, but in some highly metamorphased rocks sillimanite also occures., Under very low pressures mullite is formed, at least at high temperatures., The figure illustrating these facts is consistent with all these and other modes of occurrence of the aluminium-silicate minerals without exception, insofar as the writer is aware., It may be seen from the figure that these minerals are useful as indicators of pressures of their formation., If we can determine quantitativery the stability relation in the future, the estimation of pressure in metamorphic processes may become possible., It is quite usual that andalusite occurs in hornfelses, and kyanite in crystalline shists., The explanation of the absence of kyanite in the ordinary contact metamorphic aureole may be that the inner zone of the aureole was too intensely heated for kyanite to be stable, this mineral being stable only at low temperatures (as is seen in the figure) under moderate pressures, and in the outer zone recrystallization was not so complete as to from kyanite, or other low-temperature minerals, e., g., sericite, clay-minerals, etc., were formed instead of kyanite., In very exceptional cases, however, kyanite occurs as a product of thermal metamorphism., In most cases where the association staurolite-andulusite or kyanite-andalusite occurs, one mineral of each of these pairs shows such features as to indicate earlier formation than the other, and then the association may be regarded as one of non-equilibrium., There seems to be some cases, however, where the association represents a stable one., The stable association of kyanite with andalusite does not conflict with the mineralogical phase rule, for they are not usually the pure compounds of the compositions Al2SiO5, but contain some quantities of other compounds as solid solutions.,
    Download PDF (854K)
  • Sadakatu TANEDA
    1950 Volume 55 Issue 650-651 Pages 224-230
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The writer examined the relations between the chemical and mineral compositions of Japanese volcanic rocks., The difference between "pyroxene andesites" (rocks carrying no hornblende as phenocrysts) and "hornblende andesites" (all the rocks carrying hornblende as phenocrysts) is shown most clearly by the diagram in which the ordinate gives the ratio CaO/Na2O+K2O) and the abscissa FeO/MgO., In this diagram the former rocks all into an area with higher CaO/(Na2O+K2O) and FeO/MgO ratios, and the latter ones into an area with lower ratios, the two areas being bounded by a curve corresponding to {CaO/(Na2O+K2O)}×(FeO/MgO)=K (const., ) approximately., Moreover basic members of the pyroxene andesites tend to lie away from the boundary curve while acidic ones near the curve., The two areas are designated as "hornblende field" and the "pyroxene field"., The position of the boundary curve is not fixed, being variable in different provinces or volcanoes (Ref., Fig., 1-Fig., 7)., For example, when CaO/(Na2O+K2O)=FeO/MgO, √(K)is 1., 7 for Iizuna and Kurohime volcanoes, 1., 3 for Kayagatake volcano, 1., 1 for Asama volcano, etc., ., This figure may be used as an index showing chemical characteristics of each volcanoes or petrographic provinces., The writer proposes to call √(K)"the CaO/(Na2O+K2O):FeO/MgO Index (in short CaO·Alkalies·FeO·MgO) Index".,
    Download PDF (786K)
  • Kagetaka Watanabe
    1950 Volume 55 Issue 650-651 Pages 231-239
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The writer's purpose is to offer a classification and method of measurement of conglomerates im field geology., 1., Conglomerates shuld be defined as aqueous, coarse clastics with a cover degree ((surface ratio) of gravels more than 5%., 2., The constituent elements of conglomerate are: a) kinds of lithology of gravels and their ratio, b) size of gravels and their ratio, c) roundness of gravels and their ratio, d) cover degree (surface ratio), e) sorting, f) kinds of lithology of matrix and grade of its induration., 3., According to combination of above-mentioned elements, we can classify conglomerates as is shown in Table 2., 4., The object of making the satistics of gravels in a given river bed at present are to test the method of measurement of gravels taken, and to obtain clues to ascertain the conditions of topography, lithology and of sedimentation, which formed land, at the time of deposition., 5., writer measured recent gravels of the Arakawa river bed for a preliminary examination and derived the conclusion which can be applied also to conglomerates., a) Kinds of lithology of gravels indicate the strata and igneous rocks at the time of deposition of conglomerates., b) The mixture ratio of gravels indicate the width of the place of distribution of the lithology to which the gravels belong and the grade of erosion., c) Roundness of gravels indicate how far the gravels have been move., And it is possible to guess from the difference of roundness of gravels belong to the same lithology, the relative distance of the place of distribution., Yet, angular gravels do not necessarily indicate how far they have been moved., Therefore, in order to guess by the roundness of gravels how far they have been moved, gravels of higher grade of roundness should be paid attention to., d) The degree of erosion of gravel depend on the hardness of rock., Therefore the existence of boulders of soft rocks, indicate that the place of distribution of the strata and igneous rocks to which the gravel belongs is near., Yet though the existence of boulders of high grade and a hard rock shows enough conditions to carry the gravels, it can not be concluded immediately that the place of distribution is near by., And seldom do soft gravels travel a long distance., Therefore the meaning of the existence of soft gravels is great, and they should not be missed even when there are only a few., Soft gravels also help to guess how far they have been carried., Therefore to guess the distance of transportation by the mixture ratio of gravels, the existence of soft gravels should be paid attention to., 6., From his experience of the Arakawa river bed, the present writer worked out the methods of measurement of conglomerates, linear method, quadrate method and correlation method.,
    Download PDF (1134K)
  • Katsuhiko Sakakura
    1950 Volume 55 Issue 650-651 Pages 240-241
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    1., The author tried to determine lime contents in Miocene marl during his investigation of oil fields in Dutch New Guinea., Unfortunately, he could not complete his studies, so that only the possibility of this new method in detailed correlation and practice are described in present paper., 2., Marl samples from two hand borings located 700 meters apart were used., Apparently there are no lithological and paleontological differences., 3., Seven grams of samples taken from every two meters of core were dried in a dessicator (up to 25% of water was evaporated)., Five grams of dried sample, after treatment by hydrochloric acid, were dried and weighed., Then the lime content (actually, lime plus small quantity of other components) is calculated., All these treatments were carried on in the field, using very simple equipment capable of operation by inexperienced assistants., 4., Main Results: a., Cores from the surface to a depth of 15-20 meters are not suitable for this method (thickness of soil and subsoil was about 5 meters)., b., Marls are correlated by curves of lime content slowing in lithological characteristics., Such a examination is not possible by megascopic paleontological studies., c., This method has promise of application to marly formations, in searching for a horizon corresponding to a limestone layer which thins out.,
    Download PDF (377K)
  • Setsuji Ota, Toshio Sudo
    1950 Volume 55 Issue 650-651 Pages 242-246
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    1., "Oya-ishi" is virtric tuff composed largely of glass fragment, but including crystal fragments, such as plagioclase, quartz, common augite, biotite, the opaque minerals (magnetite, hematite), a titanium mineral, and also fragments of such rocks as liparite, pumice, and silicious types., 2., The mineralogical composition of the specimen differs slightly in each horizon (lower or middle or upper)., 3., There are initimate relations between the properties of building stone and the mineralogical properties., The glassy matrix is converted into an aggregate of very minute anisotropic material; this fact is mainly recognized in the lower horizon., The margin of each vesicule of the glass fragment is converted into the green mineral of celadonite-glauconite series, this fact is mainly observed in the middle and upper horizons., The color of "Aome" is due mainly to the green color of the mineral., Near the earth's surface, the iron-bearing minerals such as the green mineral above menrioned and hematite are negligible, and the glass fragments are colorless and altered mainly into the clay minerals of the montmorillonite group; this type is called "Shirome", Suname is the part which contains many crystal and rock fragments.,
    Download PDF (946K)
  • Hideo Minato
    1950 Volume 55 Issue 650-651 Pages 247-253
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Eight new chemical analyses of minerals of the scordite group made by the present writer have been given (Table 4), specimens being one each from the Okumitate and Toroku mines, Miyasaki Prefecture, one each from the Sasagatani and Tsunotsu mines, Shimane Prefecture and four from the Kamikinobetsu mine, Hokkaido., These are all massive, expect three specimens from the last named locality, two of which are either white or yellow powder, the remaining being light green filmy substances., To this filmy scorodite a new mineral name, aluminoscorodite, has been given., Its composition may be represented by the formula, (Al, Fe)AsO4·2H2O, where the ratio Al:Fe is 1:4., The mineral may be considered to be a variety of scorodite in which part of Fe is isomorphously replaced by Al., It is interesting to note that a new mineral, mansfieldite, corresponding to AlAsO4·2H2O was found and described by V., T., Allen and J., J., Fahey, Min., Abst., 1948, P., 353.,
    Download PDF (1038K)
  • Akira Morishita
    1950 Volume 55 Issue 650-651 Pages 254-259
    Published: April 05, 1950
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    As a result of geological surveys in 1947 and 1948 the author ascertained that there were many species of fossil echinoids in the Neogene formations of Ishikawa and Toyama Prefectures., The author identified the eight genera, fifteen species and one subspecies : Cidaris sp., a, Cidaris sp., b, Clypeaster virescens Doderlein, Clypeaster sp., indet., Echinarachnius mirabilis (Agassiz), Echinarachnius mirabilis tenuis Yoshiwara, Echinarachnius microthyroides Nishiyama, Astriclypeus manni Verill, Echinolampas yosiwarai Loriol, Linthia nipponica Yoshiwara, Eupatagus (Brissoides) sp., Shizaster recticanalis Yosiwara, Schizaster sp., ., The author tried to show the stratigraphic horizons of the echinoid-bearing members by two standard sections., Besides, he described two new species of Echinarachnius, and indicated the localities and the associated fauna of each specimen.,
    Download PDF (729K)
feedback
Top