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Volume 48 (2009)
- Issue 6 Pages 367-
- Issue 5 Pages 305-
- Issue 4 Pages 243-
- Issue 3 Pages 103-
- Issue 2 Pages 59-
- Issue 1 Pages 1-
Volume 48, Issue 6
Displaying 1-5 of 5 articles from this issue
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The Paper for the 2008 Japan Association for Quaternary Research Award
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Tadamichi Oba2009 Volume 48 Issue 6 Pages 367-378
Published: December 01, 2009
Released on J-STAGE: March 27, 2012
JOURNAL FREE ACCESS
Articles
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Norihito Kawamura2009 Volume 48 Issue 6 Pages 379-394
Published: December 01, 2009
Released on J-STAGE: March 27, 2012
JOURNAL FREE ACCESSThe Matsuyama Plain, located in the northwestern part of Shikoku Island, is one of the largest plains around Seto Inland Sea. The Pleistocene and Holocene sediments in the Matsuyama Plain are divided into the Mitsuhama, Shigenobugawa, and Matsuyama Formations. The Matsuyama Formation is subdivided into four members : the Mitsu Muds and the Mitsu Sands Members of marine sediments, the Masaki Sandy Gravel Member of estuary and/or flood plain sediments, and the Masaki Mud Member of back marsh sediments.
The Ohkaga, Iyo-1, Iyo-2, Iyo-3, and Nishi-habu Volcanic Ash Beds can be correlated to the Seiganji-Toga, Kikai-Tozurahara, Aso-4, Aira-Tn, and Kikai-Akahoya tephra beds, respectively.
The uppermost member of the Mitsuhama Formation was deposited around 620∼610 ka, early Middle Pleistocene. The middle member of the Shigenobugawa Formation was formed around 95∼85 ka, early Late Pleistocene. The upper member of the Shigenobugawa Formation was formed around 29∼26 ka, late Late Pleistocene. The ages of the Matsuyama Formation are as follows : the Mitsu Mud Member is from ca. 7,300 to 6,170 cal yrs BP, and the Mitsu Sand Member is from ca. 6,300 cal yrs BP to recent times.View full abstractDownload PDF (1960K) -
Makiko Kobayashi, Arata Momohara, Hiroko Okazaki, Tozo Okamoto, Seiich ...2009 Volume 48 Issue 6 Pages 395-404
Published: December 01, 2009
Released on J-STAGE: March 27, 2012
JOURNAL FREE ACCESSAn early Holocene fluvial event deposit with a well-preserved plant macrofossil assemblage including reproductive organs of Machilus thunbergii was found at the Okinoshima archaeological site, Tateyama, Chiba Prefecture, central Japan. To estimate the sedimentation season of the plant macrofossil assemblage, we observed seasonal changes in the morphology, size distribution, and decay process of the reproductive organs of M. thunbergii on the soil surface in an evergreen broadleaved forest. Flowers and fruits of M. thunbergii decomposed soon after they dropped to the ground. Perianth and fruits became damaged and/or chewed by insects, and size distribution of the fruit diameter changed with a lapse of time. Fossil reproductive organs of M. thunbergii from Okinoshima site included intact ovaries and perianths, and the maximum ovary diameter was between 5.0 and 5.5 mm. This means that the macrofossil assemblage had been deposited between late May and middle June. The alternating sand and mud layers including these plant assemblages seem to correspond with a flood caused by heavy rain in early summer. Our study showed that the condition of reproductive organs composing a plant macrofossil assemblage is an important clue for estimating the season of a sedimentation event.View full abstractDownload PDF (1116K) -
Takuichiro Kuwabara2009 Volume 48 Issue 6 Pages 405-416
Published: December 01, 2009
Released on J-STAGE: March 27, 2012
JOURNAL FREE ACCESSThe phytolith assemblage of a tephra-soil succession after the latter half of the middle Pleistocene drilled at the Kamikita Plain, NE Japan, shows a glacial-interglacial cycle. The phytolith assemblage was quantified for tephra-soil successions in two boring cores, which were drilled at the northern and southern Kamikita Plain. Based on fluctuations of appearance ratios of the Bambusoideae phytolith assemblage, assemblage zones A-H were identified upward in the phytolith assemblage of both cores. Assemblage zones A, C, E, and H are dominant in phytoliths of Pleioblastus sect. Nipponocalamus and Nezasa, and not dominant in phytoliths of Sasa sect. Sasa and Crassinodi. These assemblage zones show relatively warm climate periods. Assemblage zones B, D, F, and G are dominant in phytoliths of sect. Sasa and Crassinodi, and not dominant in phytolith of sect. Nipponocalamus and Nezasa. These assemblage zones show relatively cool climate periods. As assemblage zones A-H were applied to marine oxygen isotope stages (MISs 1, 2…), using the Toya tephra 112-115 ka as a time-control horizon, they were correlated to MISs 1-9. Eight marine and fluvial terraces were tephrostratigraphically correlated to assemblage zones A-H in the Kamikita Plain. Based on the correlation between assemblage zones A-H and marine oxygen isotope stages, these terraces were correlated to the stages after MIS 9.View full abstractDownload PDF (1410K) -
Akihiro Yoshida, Sadako Takeuti2009 Volume 48 Issue 6 Pages 417-426
Published: December 01, 2009
Released on J-STAGE: March 27, 2012
JOURNAL FREE ACCESSWe demonstrated the vegetation history and paleoclimate since the Last Termination from the pollen profile and radiocarbon date of the core at the Hachiro-gata lagoon, Akita Prefecture, northeastern Japan. The pollen profile indicated that 1) mixed forest of cool-temperate deciduous and boreal conifers was distributed in ca. 12 ka, 2) cool-temperate deciduous forest dominated after ca. 10 ka, and 3) Cryptomeria japonica forest rapidly expanded since 3-2 ka. We compiled spatio-temporal distribution of vegetation along the lat. 40°N line using pollen data around this region from the Last Termination to the present. Mixed forest of Betula and boreal conifers was widely distributed ca. 15 ka. In a warm climate, the cool temperate deciduous broad-leaved forest of Quercus and Fagus has been distributed since ca. 12-10 ka in the low-altitudinal areas (under 500 m a.s.l.), and since ca. 9-8 ka in the high-altitudinal areas (over 500 m a.s.l.). The rapid spread of Quercus and Fagus should show that these were their refugia in the low-altitudinal areas during the Last Glacial Maximum as well as the southern part of northeastern Japan. Since ca. 3-2 ka, C. japonica abruptly increased in the coastal region of the Sea of Japan. This would be attributed that there had been a small forest of C. japonica before this period in this region, whereas the sub-alpine coniferous forests were formed ca. 2 ka in the higher-altitudinal zone (over 1,000 m a.s.l.) of the Ohu mountain range.View full abstractDownload PDF (1255K)
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