The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
Search
Advanced search
OR
Browse
Search
Volume 51, Issue 6
Displaying 1-3 of 3 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
  • Oxidation of the manganese ore deposits of Taki mine, Iwate Prefecture
    -With special reference to the formation of amorphous manganese dioxide mineral-
    Matsuo Nambu, Katsutoshi Tanida
    1964 Volume 51 Issue 6 Pages 223-232
    Published: June 05, 1964
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.51.223
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The bedded manganese deposits of Taki, Iwote Prefecture, occur in the banded chert of paleozoic age. In the upper zone of the deposits, the ore consists of amorphous manganese dioxide mineral, cryptomelane, pyrolusìte, yokosukalite and birnessite, but in the lower zone, it consists mainly of the manganese dioxide minerals mentioned above and rhodonite with a small quantity of rhodochrosite, tephroite, jacobsite, hausmannite, galaxite, alabandite, spessartine, penwithite and goethite. It is considered that the manganese dioxide minerals are altered from rhodonite ores by weathering. The rhodonite ore was altered first into amorphous manganese dioxide mineral and thence into cryptomelane, pyrolusite, yokosukalite and birnessite.
    View full abstract
    Download PDF (511K)
  • Petrology of Nasu volcano
    Yuzo Kato
    1964 Volume 51 Issue 6 Pages 233-243
    Published: June 05, 1964
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.51.233
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Nasu volcano, about 150km. north of Tokyo, is a group of large stratovolcanoes arranged in a N-S direction. The highest peak (Chausudake) is 1917m above sea level. This volcano occupies a significant position geologically, dividing the Nasu volcanic zone into the southern and northern subzones. The basement rocks are composed of Cretaceous granitic rocks, Neogene sediments, and Quaternary welded dacitic tuffs. The activity of Nasu volcano started in the latest Pleistocene age. Tremendous volumes of basalts and mafic andesites of the tholeiite series were erupted during the first stage and the main part of the volcano is composed of them. The second stage was followed successively by eruption of intermediate andesites of the calc-alkalic rock series associated with small amounts of mafic andesites of the tholeiite series, resulting in the peaks of each stratovolcano. On the surrounding part of Chausudake which was built in the latest stage, solfataric activity is still vigorous, depositing large amounts of sulfur.
    The chemical analyses of fifteen representative rocks of Nasu volcano, including five new analyses are given in Table 1. The compositions of both tholeiite and calc-alkalic rock series are characterized by high CaO and low alkalies. However, the difference between them is clearly shown when they are plotted on the MgO-FeO+Fe2O3-Na2O+K2O diagram, and each series of Nasu volcano is distributed within the fields of the tholeiite and calc-alkalic rock series of the Nasu northern subzone.
    View full abstract
    Download PDF (688K)
  • Note on the Franciscan metamorphism
    Yotaro Seki
    1964 Volume 51 Issue 6 Pages 244-258
    Published: June 05, 1964
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.51.244
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Rocks of the Franciscan formation suffered a type of glaucophanitic regional metamorphism, being widely exposed in the Coast Ranges in California. The geological and petrological characters of the Franciscan metamorphism are outlined.
    View full abstract
    Download PDF (868K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top