The north-eastern section of Hanezuruyama consists of rocks which form part of the "Chichibu System" (Lower Permian); that is, the complex of diabase, schalstein, limestone, dolomitic limestone, dolomite and hornstone., First, the writer defines the terms dolomite, dolomitic limestone and magnesian limeston., He then recommends the AgNO 3-K 2CrO 4 method of distinguishing dolomitic limestone from the dolomite on polished surface, instead of applying "Lemberg's solution"., Second, the writer describes the microscopic characters and chemical analyses of some rocks., Finally, the writer concludes that the dolomite originates from an "authigenic sediment"., He asserts further that most of the limestones and the dolomites consist of carbnates derived from the activities of a submarine volcano, and that most of the liornstones consist of SiO 2 which is also a product of submarine volcanic activities.,

抄録全体を表示

The Tertiary formations in the vicinity of Yaitamachi, Shioya-gun, Tochigi Pref., can be divided into the Tamada, Takashio and Tadokoro formations in descending order., Judging from the Molluscan fossils, the Tamada formation may be late Miocene in age, while the Takashio and Tadokoro may belong to the middle Miocene., The Tertiary developed in the area between Tochigi-shi and Kanuma-machi is divisible into two formations, the upper, the Hukaiwa formation and the lower, the Kanuma., The former is liparitic green tuff which resembles the so-called "Oya-ishi"., The Kanuma fromation consists mainly of andesitic volcanic conglomerate and lava., but it also includes the fossiliferous Momiyama sandstone, This sandstone contains Molluscan fossils, Placopecten n., sp., etc., which seem to indicate middle Miocene., It also contains abundant Vaginulina of a more or less large type., Recently, the writer succeeded in finding several specimens of Miogypsina kotoi Hanzawa, associated with some new species of minor Foraminifera., The chronological horizon of Miogypsina kotoi is considered to be early to middle Miocene., From these facts, the age-of the Momiyama sandstone can be determined as middle Miocen., Table II is the list of the Momiyama microfauna, showing the number of individuals in 300gr, of rock sample., The writer also collected many casts and moulds of Lucina kamenooensis Otuka and minor Foraminifera from a bluish gray fine sandstone in the so-called "Terayama group" at Hachiman-yama, Ozo, Utsunomiya., This microfauna is listed in Table III., The Terayama group is generally considered to be upper Miocene in age., Judging from the microfauna, the environment under which the Momiyama sandstone was deposited was not typically warm shallow water, as shown by the coexistence of warm and cold elements., The environment of the Terayama group" in Utsunomiya is suggested to be middle neritic from the microfauna., Several fossil plants as shown in Table I were collected from Iwafune-yama, Iwafune-mura, Shimotsuga-gun, Tochigi Pref., This mountain consists mainly of andesitic to dacitic agglomerate, intercalated with thin beds of tuffaceous mud and cross-bedded sandstone containing fossil plants., This fossil flora shows a close resemblance to the mild climatic forest of the central part of Japan proper, though it contains some warmer climatic elements, such as Cyclobalanopsis acuta, Carpinus Tschonoskii, Euptelea polyandra and Tilia kiusiana., From these facts, it seems likely that the Iwafune-yama agglomerate is a member of the Kanuma formation.,

抄録全体を表示

The writer recognizes two distinct systems in the classification of strata., One is a lithologic classification defined solely by lithologic characters and the other is a bio-chronologic classification defined solely on basis of bio-chronologic time-concepts., In the former, four fundamental units (stratum [bed], member, formation, group) and four supplemental units (subformation, superformation, subgroup, supergroup) are recognized., Stage, series, system and erathem belong to the biochronologic classification.,

抄録全体を表示

The principal carbonate molecules in manganiferous carbonate minerals are MnCO 3, CaCO 3, FeCO 3 and MgCO 3., The compositions of the manganiferous carbonates are plotted in three ternary diagrams., A mineral appears in all three field if Ca, Mg and Fe are equally abundant., In plotting, a fourth metal in small quantity is added to others as follows: if Ca, it is added to Mg; if Fe, it is added to Mn, and if Mg, it is distributed 3/4 to Ca and 1/4 to Mn., Rhodochrosite, Mn-rich, occurs in the interspaces between rhodonite crystals as a product of the mineralization of the first period of the Kamiina Mine., Some varieties of rhodchrosite associated with tephroite and alabandite are also found among the products of the next several mineralizations., The Ca-rhodochrosite forming narrow veinlests is condidered to be the last carbonate mineral traversing the main part of the ore deposit., The evolution of maganiferous carbonates usually takes place in the following order in manganese deposits: Fe-Mn calcite →Fe-rhodochrosite →Ca-rhodochrosite →rhodochrosite →Ca-rhodochrosite →Mn-calcite., In epithermal veins the succession of ore minerals is usually quartz, pyrite, sphalerite, galena, finally argentite, gold and quicksilver., Undoubtedly it represents in the main decreasing temperature., Rhodochrosite, very rich in Mn, is found as a constituent of zinc and lead veins., Rhodochrosite, somewhat lime-rich, occurs in the gold and silver veins or quicksilver veins.,

抄録全体を表示