All issues
Volume 60, Issue 710
Displaying 1-4 of 4 articles from this issue
- |<
- <
- 1
- >
- >|
-
Takashi MITSUNASHI1954 Volume 60 Issue 710 Pages 461-472
Published: November 25, 1954
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe Pliocene marine sediments exposed on the dipside route along the River Koito demonstrate a remarkable change in rock facies towards the west., To cleariby the chronological interrelation of the various rock facies, the many pyroclastic key beds were traced in the field., Thereby the interrelation of the extension of each rock facies in time and space was confirmed., The basal characters of the Ichijiku sand facies and the Higashihigasa sand and gravel facies are not unconformable as previously thought, but these coarse sediments merge rapidly and laterally into fine-grained sediments (Figs., 2∼6)., New time and rock-time units are introduced based upon two adequately selected key layers which are considered to be of simultaneous deposition.,View full abstractDownload PDF (1554K) -
Tatsuo YAMASAKI, Yoichiro MORINAGA1954 Volume 60 Issue 710 Pages 473-486
Published: November 25, 1954
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe stratigraphical relation between the Karatsu and Sasebo coal-fields has been discussed by many geologists, but opinions diverge concerning the boundary between the Kishima (Ashiya) and Sasebo (Ainoura formation) groups., Detail observations on the said boundary, especially on the lower parts of the latter and the top of the former groups in the Karatsu coal-field, led the writers to review Ueji's classification of the Ainoura formation, and to add supplementary notes to previously published reports on the Kishima group., The newly proposed boundary between the Sasebo and Kishima groups is based upon the following stratigraphical data: (1) Marked differences in lithology between the coal-bearing formation of the Sasebo group above, and the "flysch" type Hatazu shale comprising the top of the Kishima group below., (2) The Kishima group is missing in the northeast of the Karatsu coal-field, where the redefined Sasebo group directly overlies the Pre-Tertiary basement complex (granites)., The Hatazu shale is separated from the overlying thin basal conglomerate (ca., 1 m thick) of the Sasebo by an erosion surface., The conglomerate contains angular boulders having lithological characters identical with the underlying strata., From such evidence, the writers conclude that tilting of the area towards the northeast may have begun as early as the beginning of deposition of the Sasebo group in the northern extremity (present day Higashimatsura Peninsula) of the Karatsu coal-field., On the other hand, crustal movement caused a shift in the position of the Kishima basin near the end of the Kishima (Ashiya) age, as already stated elsewhere., (3) Although the geological age of the Sasebo and Kishima groups have long been believed by most Japanese geologists to be Oligocene, the writers hold the view that the Paleogene-Neogene break should be defined by the Kishima-Sasebo boundary., This view is upheld by the above-mentioned evidences supplemented by paleontological data., However, the writers admit that further paleontological data is necessary to settle the problem., It is expected that future paleontological investigations will favour this assumption.,View full abstractDownload PDF (1870K) -
Shohei KOKAWA1954 Volume 60 Issue 710 Pages 487-493
Published: November 25, 1954
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSThe age of the small andesite knolls such as Mts., Mikasa and Kasuga, which fringe the eastern brink of the Nara Basin, has now become fairly clear by the writer's field survey, the results are: The stratigraphic sequence in this area from the older to the younger is:(1) "Fujiwara" Formation (Marine doposits, F2-F3)(2) "Jigokudani" Formation (Fresh-water deposits, ? F3-G-H1; rich in endocarps of Styrax obassioides MIKI., )(3) "Shirakawaike-Saho" Formations (Fresh-water deposits, I1-I2?)(4) Upper gravel beds (J-K) Three tectonic lines of north to south trend prevail, these govern the distribution of the sediments and the arrangement of the volcanics., Concerning the geologic age of the "Mikasa-andesite", the important facts confirmed are: a) Over and under the lava, some parts of the "Shirakawaike-Saho" F., exist and the sheet-formed "Mikasa-andesite" is inserted concordantly in the sediments., b) Gravels of the Mikasa-andesite, though not abundant, are contained in the middle and upper parts of "Shirakawaike-Saho" F., c) The lower part of the "Shirakawaike-Saho" F., is rich in its yield of the so-called "Metasequoia-flora", such as Metasequoia disticha (HEER) MIKI, Picea Koribai MIKI, Juglans megacinerea CHANEY etc., From the above-mentioned facts it was concluded that, the horizon of "Mikasa-andesite" occupies the lower part of the "Shirakawaike-Saho" Formations, which may be assigned to Plio-Pleistocene (I1).,View full abstractDownload PDF (829K) -
Koji FUJII1954 Volume 60 Issue 710 Pages 494-500
Published: November 25, 1954
Released on J-STAGE: April 11, 2008
JOURNAL FREE ACCESSDownload PDF (954K)
- |<
- <
- 1
- >
- >|