Masao Minato

ON THE VOLCANIC ROCKS IN THE JAPANESE PALEOZOIC, FIRST REPORT — GOTLANDIAN AND DEVONIAN

Gotlandian and Devonian deposits are typically developed in a relatively narrow strip around the Sakari and Ichinoseki districts of the Kitakami mountains. In this report, the typical section of pyroclastic sediments found in those deposits are described as to lithic character, thickness and stratigraphical horizon. The volcanic rocks and associated sediments reported from the Gotlandian deposits of Japan outside the Kitakami district are briefly outlined. In short, the volcanic rocks and their associated pyroclastic sediments are especially dominant in the Lower to Middle Devonian (Ohno and Nakazato series), but rather few in the Gotlandian (Kawauchi plus Takainari series) and Upper Devonian (Tobigamori series) in the Kitakami mountains. Of them, keratophyric rocks are prevalent in the Lower Devonian Ohno and Middle Devonian Nakazato series, while diabasic rocks are found in the Lowest Kawauchi series of Middle Gotlandian age, and in the lowest and uppermost parts of the Nakazato series and in the Tobiga...

ON THE AGE OF METAMORPHISM IN THE JAPANESE ISLANDS

The distribution, lithology, and previously held theories on age of metamorphic activity in Japan are outlined. Precise age determination of each metamorphic complex is still uncertain. The latest was probably Miocene, the earliest either Precambrian or as late as Devonian. Miocene metamorphism affected the so-called green tuff region of the Inner zone of Japan. The Hida gneiss is the result of the oldest age of metamorphism. Absolute age determination of 230 x 106 years has been made of minerals in the Ryoke gneiss although recurring metamorphism has been shown for its area. Considerable granite emplacement occurred during the Cretaceous and early Tertiary. The age of metamorphism resulting in the Sambagawa-Mikabu complexes is much in dispute but is probably older than late Triassic. M. Russell

ON THE VOLCANIC ROCKS IN THE JAPANESE PALEOZOIC, SECOND REPORT - CARBONIFEROUS

The Carboniferous deposits typically developed in the Kitakami mountains, Japan, have been divided into the following five series in ascending order: Hikoroichi, Arisu, Ohdaira, Onimaru and Nagaiwa series respectively. Of them the Hikoroichi series is divided into the Ikawa and Ohmata stages; the Arisu into the Hinozuchi and jiamonji stages; and the Ohdaira series into the Maide and Kozubo stages. Volcanic rocks and pyroclastic sediments are dominantly found in the lower three formations of the Hikoroichi, Arisu and Ohdaira series, while they seem to be entirely lacking in the Onimaru series, although they are again developed in the Nagaiwa series. Most of those volcanic rocks and their associated sediments are represented by such basic rocks as diabase or schalstein, but porphyrite is frequently found as a tuff or flow (?) in the Ikawa stage, the basal part of the Ohmata stage and also in the basal part of the Hinozuchi stage. Further, similar porphyrite tuff is found in the basal part of the Yornogibata...

ON THE VOLCANIC ROCKS IN THE JAPANESE PALEOZOIC, THIRD REPORT, PERMIAN

Permian deposits widely developing in the southern Kitakami mountains have been divided into the Sakamotosawa series, the Kanokura series and the Toyama subsystem in ascending order. Volcanic rocks and their associated pyroclastic sediments are rather rare in the Permain deposits of those mountains, however, there exist thin liparitic or dacitic tuffs and “schalstein” in the Sakamotosawa series ranging from the Pseudoschwagerina to the lower half of the Parafusulina zone in age. Except for the Sakamotosawa series, volcanics and their pyroclastics have never been found in the Permian systems in that area The Kanokura series is further diyided into, in ascending order, the Kattisawa and Iwaisaki stages. Lepidolina multiseptata horizon of the Iwaisakistage may be possibly correlative to the middle to upper Neoschwagerina zone, while the Lepidolina gigantea horizon of the same stage may be nearly equivalent to the Yabeina globosa zone. Outside the Kitakami mountains, a large amount of volcanic rocks and their...

Veränderung des Salzgehaltes in den küstennahen Seen Hokkaidos

Es ist eine schon feststehende Tatsache, dass die kustennahen See am ochotskischen Meere, besonders die Wasserbezirke des Abashiri-Sees, vom Beginne des Alviurn sich allmahlich versusst haben. Hier tritt palaographisch etwa wahrend dieser 10, 000 Jahre ein Wechsel ein vom Paphia-Meer (Meerwasser) durch die Ostrea Meerbucht (polyhalin) und durch den Corbicul a-See (mesohalin) zum Anodonta-See (oligohalin).Im Gegensatz hierzu ist das Wasser des Abashiri-Sees in der Tiefe in neuester Zeit viel, salzhaltiger als fruher geworden, wie Tabelle 1 zeigt. Vergleicht man den Salzgehalt von 1950 mit jenem von 1933, so hat sich der Salzgehalt um mehr als das zehnfache verrnehrt. Beinahe dieselbe Erscheinung wurde im Tombetsu-See beobachtet.Die Ursache der oben erwahnten Tatsachen ist noch unbekannt, aber der Verfasser vermutet, dass in der Nahe des Abashiri-Sees und des Tombetsu-Sees in neuester Zeit eine allrnahliche Senkung stattgefunden hat, sodass das Meerwasser mehr als fruher in diese See einfliessen kann. Aus diesem. Grunde ist das Wasser dieser Bezirke salzhaltiger geworden.Wenn diese Vermutung richtig ist, dann kann man sicherlich die Veranderung des Salzgehaltes der kusten.nahen See nutzbar verwenden, um die wenigen Krustenbewegungen zu erkennen.

Pseudoschwagerina-Vorkommen in Kirin-Formation (Mandschurei)

滿洲國吉林省盤石縣明城附近より産出せるPseudoschwagerinaに就いて報告した。所謂北滿型の古生層(小林博士の滿蒙層群)の中ではPseudoschwagerinaの産出は從來知られてゐなかつた。明城の現地に見た範囲では, 此の紡錘蟲帶は, Gigantella動物群を産する化石帶に近接してゐる。此の事は二壘石炭紀境界問題に關聯して, 濫りに看過す可き事でないと思はれる。