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Volume 36 (1982)
- Issue 6 Pages 307-
- Issue 5 Pages 231-
- Issue 4 Pages 175-
- Issue 3 Pages 117-
- Issue 2 Pages 55-
- Issue 1 Pages 1-
Volume 36, Issue 4
Displaying 1-7 of 7 articles from this issue
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Keiji MATSUOKA, Fossil Mollusc Research Group for Noiiri-ko ExcavationArticle type: Article
1982 Volume 36 Issue 4 Pages 175-184b
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSThe fossil embryonic shells of the genus Semisulcospira (Mesogastropoda: Pleuroceridae) had been obtained from the latest Pleistocene Nojiri-ko Formation, lacustrine deposits, seasonally exposed on the bottom of Lake Nojiri, Nagano Prefecture, Central Japan. The fossil-bearing horizon is the upper part of Section H of the Middle Nojiri-ko Formation and the age is approximately estimated at 27,000 y. B. P. by the 14C method. The fossil embryonic shells preserved in a mature female whorl are 12, a well-preserved one of which is 0.87mm in height and 0.76mm in width; the sculpture consists of spiral and growth lines or striae; the body whorl has a round periphery. By comparison with the embryonic shell of the Recent Japanese Semisulcospira libertina group including S. libertina (Goutn), S. reiniana (BROT), S. kurodai KAJIYAMA et HABE, and S. trachea (WESTERLUND), this fossil embryonic shell is identified with S. libertina (GOULD) which is widely distributed over the Japanese Islands, eastern area of China, Formosa, and southern area of Korea. Also the fossil that the embryonic shell ratio height/width is 1.14 was inferred to be 2.25 whorl stage in a brood pouch of the female by statistical analysis. From the occurrence of S. libertina (GOULD) from the Nojiri-ko Formation, this species shows to have bred in Lake Nojiri of the latest Pleistocene, and the temperature conditions necessary for S. libertina (GOULD) to breed can be beduced from the annual birth behavior of S. cancellata (BENSON) and S. libertina (GOULD). It is assumed that the population of Nojiri-ko libertina in the last glacial period corresponds to a population of higher latitude than that of Lake Nojiri in present day. Furthermore, we discuss on the ecology of S. libertina (GOULD) that helps to know the paleoenvironment of Lake Nojiri in this age.View full abstractDownload PDF (2868K) -
Masakatsu SASADA, Tohru SAKIYAMA, Shigeru IIZUMI, Hiroji HONMA, Kaoru ...Article type: Article
1982 Volume 36 Issue 4 Pages 185-198b
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSPaleogene intrusive rocks are distributed in the eastern part of the San'in province, Southwest Japan. They are called the Namariyama Intrusives. They are tonalitic to granitic in composition and are commonly characterized by porphyritic texture. They are easily discriminated from the Late Cretaceous Imbi Intrusives in the same province by means of the characteristic porphyritic texture. The authors will describe the geology, petrography and mineral chemistry of the Yubarako granophyre intrusion, one of the largest massif of the Namariyama Intrusives, in this paper. The Yubarako granophyre intrusion occupies an area of about 67 km2 and crops out as a gourd-shaped body in the northern part of Okayama Prefecture. It consists largely of the leucocratic porphyritic rocks, that is, granophyre, granite porphyry and fine-grained granophyre. They are granitic in composition, commonly including phenocrysts of quartz, plagioclase and biotite. The texture of groundmass is, however, gradually changing from the granophyre, granite porphyry to the fine-grained granophyre. They are distributed from center to margin in this order. It is concluded that varying cooling condition in the intrusion gave rise to this textural variation. The emplacement of the leucocratic porphyritic rocks was preceded by the formation of small bodies of the granodiorite porphyry at the margin of the Yubarako granophyre intrusion, and was succeeded by the injection of many thin aplitic dikes in the southern part of the intrusion. Compared with the Late Cretaceous plutonic rocks in the San'in province, the Yubarako granophyre intrusion is characterized by lower K2O/Na2O in whole rock composition, and by higher Mg/Fe ratio in biotite, lower Or/Ab ration in potassium feldspar.View full abstractDownload PDF (2546K) -
Kenji SHUTO, Ryuichi YASHIMAArticle type: Article
1982 Volume 36 Issue 4 Pages 199-213
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSThere are two main rock series in non-alkalic igneous rocks: the calc-alkalic rock series and tholeiitic rock series. The calc-alkalic rock series is characterized by increasing of SiO2 contents and gradual decreasing of FeO contents (tatal iron as FeO) with changing from mafic rocks toward felsic ones. On the other hand the tholeiitic rock series shows lower degree of SiO2 enrichment, and rapid increasing of FeO contents and FeO/MgO ratios with changing from mafic rocks toward intermediate ones. Kuno (1950) considered that there are two different rock series in non-alkalic basalt, andesite, dacite and rhyolite in the Izu-Hakone region, central Japan: the hypersthenic rock series (volcanic rocks with groundmass hypersthene) and the pigeonitic rock series (with only clinopyroxenes in the groundmass). Kuno (1965) considered, moreover, that the variation trend in chemistry of the hypersthenic rock series agrees with that of the calc-alkalic rock series and he proposed to confine his hypersthenic and pigeonitic rock series to the calc-alkalic and the tholeiitic rock series respectively. However, the bulk chemical compositions analyzed by the present writer for Miocene volcanic rocks from the Kitakami river basin and the Ryozen district in northeast Japan can not be divided into the distribution fields of the hypersthenic and pigeonitic rock series in any of the diagrams such as AFM, (FeO+Fe2O3×0.9)/MgO-SiO2 and (FeO+Fe2O3×0.9)/Mg-(FeO+Fe2O3×0.9). The same feature is also recognized in volcanic rocks of several Quaternary volcanoes in the Japanese Islands, such as Osore-yama, Nekoma-dake and Bandai-san belonging to the Nasu volcanic zone, Chokai-san and Iwaki-san in the Chokai volcanic zone and Aso-san in Kirishima volcanic zone. Pliocene Kitamatsuura basalts in northern Kyusyu give the same evidence. Therefore it may be not valid to regard that the Kuno's hypersthenic and pigeonitic rock series correspond respectively, to the calc-alkalic and tholeiitic rock series. In the present paper, it shuold be emphasized that the calc-alkalic rock series is not clearly distinguishable from the tholeiitic rock series by the above three diagrams and the petrogenetical implications on the distinction between the two rock series are discussed.View full abstractDownload PDF (1289K) -
Kiyoshi OKUMURA, Shinogu ISHIDA, Yoshinari KAWAMURA, Mituru KUMADA, Su ...Article type: Article
1982 Volume 36 Issue 4 Pages 214-218
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSKumaishi-do Cave, which is situated at Hachiman-cho, Gifu Prefecture, Central Japan (Long., 137° E; Lat., 35°45'N), is one of the largest limestone caves in this district. The fissure sediments which expose near the entrance of the cave, yield abundant mammalian fossils of the Latest Pleistocene. The fossil assemblage contains 28 forms of mammals. The total ratio of the extinct and exotic forms attains about 50% in large mammals, but only 11% in micro-mammals. It is interesting that the boreal forms such as Alces alces (LINNAEUS) and Ursus arctos LINNAEUS are associated with the temperate forms such as Selenarctos thibetanus (G. CUVIER), Macaco, fuscata (BLYTH) and Sinomegaceros yabei (SHIKAMA). In micro-mammals, it is characteristic that most forms are extant, but the forms which are now distributed sporadically in high mountains are predominant in insectivore assemblage, and extinct and exotic forms such as Microtus epiratticeps YOUNG and Clethrionomys sp. are rarely found. The fossil bones which are obtained from the lower part of the fossiliferous sediments are dated as 16720 ± 880 y. B. P. by 14C method. The age is assigned to the coldest phase of the Wiirm Glacial time in Japan, so it is consistent with the fact that the boreal elements are contained in the assemblage. The occurrences of Palaeoloxodon naumanni (MAKIYAMA), Alces alces, Cervus praenipponicus SHIKAMA, Microtus epiratticeps and Clethrionomys sp. from Kumaishi-do Cave are one of the youngest records in Japan. It is considered that the mammalian fauna of Japan dramatically changed from ca. 16000 to 10000 y. B. P. Many large mammals were extinguished as the climate became warmer since 16000 y. B. P. On the other hand, most of micro-mammals survived to the recent. These facts probably indicate that the large mammals severely suffered the effects of the isolation of the Japanese Islands from the continent and the hunting activities of men.View full abstractDownload PDF (583K) -
Hiroyuki MISHIMA, Mankichi HORIGUCHIArticle type: Article
1982 Volume 36 Issue 4 Pages 219-223
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSDownload PDF (667K) -
Ichinotani Research GroupArticle type: Article
1982 Volume 36 Issue 4 Pages 224-228
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSDownload PDF (781K) -
14C age of the Quaternary deposits in Japan (143)Yaeko IGARASHI, Yoshiki FUJIWARAArticle type: Article
1982 Volume 36 Issue 4 Pages 229-230
Published: July 25, 1982
Released on J-STAGE: July 26, 2017
JOURNAL OPEN ACCESSDownload PDF (288K)
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