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Volume 38 (1999)
- Issue 6 Pages 423-
- Issue 5 Pages 353-
- Issue 4 Pages 271-
- Issue 3 Pages 177-
- Issue 2 Pages 85-
- Issue 1 Pages 1-
Volume 38, Issue 2
Displaying 1-9 of 9 articles from this issue
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Shigehiro Ishizuka, Kimiyasu Kawamuro, Hiroshi Minami1999 Volume 38 Issue 2 Pages 85-92
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThere has been controversy over the pedogenic process of Black soils and Brown forest soils that developed on Quaternary tephras. Stable carbon isotopic technology can provide direct evidence of the process of humus accumulation on these contrasting types of soils.
We measured δ13C (13C/12C) humus values of a Black soil and a Brown forest soil, which were thought to have the same parent material, located near Hakkoda, in the northern part of the Tohoku district, Japan. In this region, two marker-tephras are interstratified in the soil profile and make it easy to study the pedogenic process. Soil pollen analysis clarified that non-arboreal pollen mainly consisting of Gramineae was dominant in A and buried A horizons of Black soil. On the other hand, almost all of the pollen detected in the horizons of the Brown forest soil was arboreal. The results implied that the soil organic matter is derived from the degraded remains of these plants.
The δ13C value was -20∼-18‰ in Black soil and -25∼-22‰ in Brown forest soil. This result suggested that 45∼53% of the organic matter of Black soil derives from C4 plants, such as Miscanthus sinensis and Imperata cylindrica. This is direct evidence that the grassland vegetation composed of Miscanthus sinensis was an important source of organic matter and continuously provided soil organic matter at least during the past 4, 000 years on Black soil. On the other hands, in Brown forest soil most of the soil organic carbon was derived from C3 plants, such as Fagus, Pinus, and Quercus.View full abstractDownload PDF (886K) -
Shinji Nagaoka, Yasuhide Maeda, Mitsuru Okuno1999 Volume 38 Issue 2 Pages 93-107
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThe paleogeography and sea-level change during the Holocene in Nagasaki Bay are discussed on the basis of aerial photographs, borehole data, molluscan fossils, and 14C dating.
Recent formations in Nagasaki Bay and the Nagasaki Lowland are divided into four members: Urakamigawa Basal Gravel: Urg, Dejima Clay: Djc, Matsuyama Gravel: Mtg, and the artificial deposit: Ard. Urd is composed of fluvial gravel beds which were deposited in the basal valley during the last glacial period. The Djc is clayey to silty sediments with many marine molluscs, and was formed in the delta and the bay during the Holocene transgression. Mtg is fluvial sand and gravel beds including archeological material from the Holocene. Ard is artificial material beds deposited after A. D. 1571 when Nagasaki Port opened. The Ard member includes the high-temperature oxidized red sandy layers formed by the atomic bombing in 1945.
The 14C dating for intertidal molluscan fossils shows that the sea level was -16m in ca. 8, 000yrs BP, and rose to 0.5m below the maximum level of the Holocene transgression in ca. 4, 000yrs BP. Sea level since 4, 000yrs BP has been stable.View full abstractDownload PDF (2020K) -
Shinji Sugiyama1999 Volume 38 Issue 2 Pages 109-123
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThis study aims to clarify the development of lucidophyllous forests since the Last Glacial Age in south Kyushu using phytolith analysis. Abundant arboreal phytoliths in volcanic ash soils are used as one of the best indicators of past forest vegetation and for dating relies on several distinct tephra layers occurring within the soil.
In the first stage of the Last Glacial Age, 65, 000 years ago, lucidophyllous forests composed of evergreen trees such as Castanopsis occurred exclusively in Tanegashima island off the southern coast of mainland Kyushu. Then lucidophyllous forests composed of Lauraceae appeared in Satsuma Peninsula ca. 11, 000 years BP. Almost the entire coastal areas of South Kyushu and inland areas had been occupied by lucidophyllous forest by ca. 6, 300 years BP.
Grassland vegetation composed of Pleioblastus sect. Nezasa and Miscanthus, however, occurred in the inland area where humic volcanic ash soil, Kuroboku, was formed. Dominance of lucidophyllous forests in the whole of south Kyushu as it is today was completed about 4, 200 years BP.
The great explosive eruption of ca. 6, 300 years BP from Kikai caldera caused a spectacular volcanic disaster in Kyushu and adjacent areas. A significant change in phytolith assemblages below and above the Koya pyroclastic flow suggests that this hazardous pyroclastic flow had changed vegetation from evergreen forest to grassland represented by Miscanthus in southern Osumi and Satsuma peninsula. Recovery of lucidophyllous forests followed about 600 years after the volcanic event. In other areas of south Kyushu, where the pyroclastic flow did not arrive but only ash fell thickly, relatively minor volcanic effect on lucidophyllous forests was suggested.View full abstractDownload PDF (2710K) -
An Approach Using Diatom Fossil AssemblageChieko Shimada, Shiro Hasegawa1999 Volume 38 Issue 2 Pages 125-144
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSA Q-mode principal components analysis (PCA) based on downcore variation of diatom fossil assemblage was carried out in order to reveal the late Quaternary paleoceanography of the NW Pacific margin with the qualified submarine core KH 94-3, LM-8, recovered off the Sanriku coast, NE Japan.
It is recognized that increase of diatom valve concentration (DVC: valves/g) occurred in oxygen isotopic Stage 3 (interstadial during the last glacial) and Stage 1 (Holocene). However, diatom assemblages show drastic change between the two periods. As the result of PCA, we delineated four principal components explaining 93.6% of total variance. Principal compoent 1 is composed mainly of Thalassionema nitzschioides (Grunow) H. et M., which dominates in the coldest Stages 4 and 2 with diatom valves being poorly preserved and DVC being the lowest. Principal component 2 with some ice-related diatoms predominates in Stage 3, whereas principal component 3, which is characterized by Neodenticula seminae (Simonsen et Kanaya) Akiba et Yanagisawa and Odontella aurita (Lyngbye) Agardh, displays high values in Stage 1.
Here, we suggest that intensified discharge of sea ice originated in the Sea of Okhotsk in Stage 3. This interpretation subsequently enables us to explain the high DVC during the period as being due to high productivity at the sea ice edge. We can also infer that the qualitative difference in the Oyashio between the glacial and the interglacial is due to change in the supplying mode of the Okhotsk-originating factor such as sea ice, and consequently that there is a different mechanism of high primary productivity in the area off Sanriku during each period.View full abstractDownload PDF (3863K) -
Jun-Ichi Kimura, Shomei Okada, Katsuhiro Nakayama, Koji Umeda, Takashi ...1999 Volume 38 Issue 2 Pages 145-155
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSZircons from tephras from Sambe and Daisen volcanoes, in the San-in district, Japan, have been dated by fission track method. The Daisen tephras dated are DNP (80±40ka), DHP (140±50ka), DMP (180±60ka), HdP (170±60ka), DOP (190±60ka), hpm 1 (230±70ka), and cpm (330±90ka) plinian pumice fall deposits and a NwF (100±40ka) block and ash flow deposit. Those dated from Sambe are the K 2 (100±30ka) ignimbrite and the K3 (100±20ka) pumice fall deposit. Errors are large due to the young ages; mean ages obtained are consistent with tephra stratigraphy and chronology using depositional rates of interbedded loess. DMP and DHP are exceptions, however. Their mean ages are older than the expected ages deduced from paleoclimatology, which suggests eruption at the beginning of the Late Pleistocene (-120ka). Based on the stratigraphy and ages obtained, it is concluded that the Middle-Late Pleistocene boundary is located between HdP and DMP. Explosive volcanism at Daisen volcano is considered to have begun not later than 350ka, with more than thirteen plinian tephra eruptions taking place by about 100ka, followed by seven or more plinian eruptions up to the present. Plinian eruptions at Sambe volcano commenced at about 100ka, and five tephras erupted in the Late Pleistocene.View full abstractDownload PDF (1535K) -
Masakazu Hayashi1999 Volume 38 Issue 2 Pages 157-162
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSSeveral fossil insects were obtained from the Middle Pleistocene (ca. 0.35-0.30 Ma) in Agatsuma-machi, Gunma Prefecture, central Japan. Most fossils of Donaciinae can be identified as Plateumaris sericea based on characteristics of the pronotal median line and the male genitalia, which distinguishes it from P. shirahatai. This fossil record is one of the oldest records of P. sericea in Japan. In the case of fossil specimen, critical discrimination of P. sericea and P. shirahatai is quite difficult. In this paper, I described fossil specimens of P. sericea and pointed out several problems for its identification in the fossil record of Japan.View full abstractDownload PDF (1192K) -
Toshiro Nagasako, Mitsuru Okuno, Hiroshi Moriwaki, Fusao Arai, Toshio ...1999 Volume 38 Issue 2 Pages 163-173
Published: April 01, 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSThis paper discusses the paleogeography of the Kimotsuki Lowland, southern Kyushu Island, during the middle to late Holocene based on tephrochronology and AMS 14C dating.
As indicated by the Ikeda pumice fall on the berm deposits, the most landward baymouth barrier was formed about 5.5-5.7ka, and the entire barrier appears to have been formed within about 100 years. The relative height of sea level at that time is estimated to be about 3-5m above the present sea level.
Five tephra layers occur in the peat deposits, four of which are identified as the Sakurajima-Takatoge 2 (4.5ka), the Kirishima-Miike (4.2ka), the Kaimondake-9c (2ka) and the Kaimondake-12a (A. D. 874). The fifth layer has not yet been correlated. Three AMS 14C dates obtained from the base of the peat deposits, along with the tephrochronology, indicate that the accumulation of the peat began 5.6ka to 5.0ka and lasted for at least 4, 000 years.View full abstractDownload PDF (1518K) -
1999 Volume 38 Issue 2 Pages 176a
Published: 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSDownload PDF (79K) -
1999 Volume 38 Issue 2 Pages 176b
Published: 1999
Released on J-STAGE: August 21, 2009
JOURNAL FREE ACCESSDownload PDF (79K)
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