MIS34-P01

Room:Convention Hall

Time:May 27 18:15-19:30

Paleoenvironmental changes in NW Panthalassa through the Toarcian OAE: Stratigraphy
and geochemistry of the Toyora area
IZUMI, Kentaro1∗ ; KEMP, David2
1

Center for Environmental Biology and Ecosystem Studies, NIES, 2 Department of Geology and Petroleum Geology, Universityof Aberdeen
The early Toarcian (Early Jurassic) oceanic anoxic event (T-OAE) was a significant palaeoenvironmental perturbation that led
to marked changes in ocean chemistry and climate, and which also had a severe impact on marine ecosystems. In addition, thisevent is characterized by the widespread occurrence of a ˜3?7 ‰ negative excursion in the carbon-isotope (δ 13 C) compositionof marine organic and inorganic matter and terrestrial plant material. This feature of the event indicates a pronounced perturbation to the global carbon cycle. Despite such global impacts of the event, the precise palaeoenvironmental changes during theevent from sections outside of the Boreal and Tethys realms are uncertain. Thus, to resolve this issue and further expand ourunderstanding of the nature of the event, here we investigated the Nishinakayama Formation of the Toyora area, southwest Japan,
which represents shallow-marine strata deposited at the northwestern margin of the Panthalassa Ocean. First, we establishedhigh-resolution carbon-isotope chemostratigraphy. A characteristic δ 13 C negative excursion was recognized around the middle
part of the Nishinakayama Formation, allowing accurate international correlation. Then, we carried out geochemical analyses
to reconstruct palaeoenvironmental conditions at the northwestern Panthalassic margin. Our results indicate that in the studied
succession, organic-matter enrichment persisted through the early Toarcian, but elemental redox proxies and ichnofabrics do notsupport persistent bottom-water anoxia through the δ 13 C excursion. Analysis of terrigenously derived major and trace element
abundances and palynology, coupled with sedimentological observations, revealed an increase in coarse-grained sediment, phytoclast size, and terrestrial organic-matter close to the onset of the δ 13 C negative excursion. These lines of evidence potentiallysuggest a marked strengthening of detrital sediment flux and hence hydrological cycling and continental weathering. This isconsistent with previously published evidence from Boreal and Tethys realms.

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MIS34-P02

Room:Convention Hall

Time:May 27 18:15-19:30

Silicoflagellates and surface water-mass variation at ODP Site 704 in the South Atlantic
Ocean for the last 10Myrs
ONODERA, Jonaotaro1∗ ; SEKI, Osamu2
1

JAMSTEC-RCGC, 2 Institute of Low Temperature Science, Hokkaido University

At ODP Site 704 (46.9◦S, 7.4◦E) in the South Atlantic Ocean, we estimated latitudinal migration of subpolar and subtropicalsurface water masses for 10 million years on the basis of silicoflagellate fossil assemblage variations in the sediment core samples.
Biogeographical silicoflagellate distribution corresponds to cold water and subtropical water masses. This distribution pattern canbe applied to the estimation on latitudinal migration of subpolar/subtropical boundary. Although the fossil preservation was poorin the oldest period from 10Ma to 6.5Ma, the extinct genus Bachmannocena considered as a temperate or cosmopolitan species
was observed for the period. Continuous occurrence of the cold water genus Distephanus was observed from ˜6.5Ma to present.
The modern annual sea-surface temperature (SST) is 5.6 ℃ at the studied site, and silicoflagellate assemblage is composed of thegenus Distephanus . The relative abundance of sea ice-related species in the silicoflagellate assemblages increased from 2.7Ma.
However, subtropical genus Dictyocha intermittently dominated the assemblage from 5.7Ma to 4.0Ma. The co-occurrence ofcold and subtropical water species suggest that the subpolar/subtropical boundary or the mixed water had covered the studied
site. The temporal increase of subtropical silicoflagellates at the same periods had been reported at ODP Site 1165 (64.4◦S)located in further south near the Antarctic. However, it should be noted that alkenone SST did not show the clear increase at the
study site for the occurrence period of Dictyocha .
Keywords: silicoflagellate, biogeography, paleoceanography, Ocean Drilling Program (ODP), South Atlantic Ocean

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MIS34-P03

Room:Convention Hall

Time:May 27 18:15-19:30

Relative sea level records using high-resolution radiocarbon dating based on new sediment cores from the Bonaparte Gulf
ISHIWA, Takeshige1∗ ; YOKOYAMA, Yusuke1 ; MIYAIRI, Yosuke1 ; OBROCHTA, Stephen2 ; SASAKI, Takenori3 ;IKEHARA, Minoru4 ; UEHARA, Katsuto5 ; KITAMURA, Akihisa6 ; SUZUKI, Atsushi7 ; IKEHARA, Ken7 ;KIMOTO, Katsunori8 ; BOURJET, Julien9 ; MATSUZAKI, Hiroyuki3
1

Atmosphere and Ocean Research Institute, The University of Tokyo, 2 Faculty of International Resource Science, Akita University, 3 The University Museum, The University of Tokyo, 4 Center for Advanced Marine Core Research, Kochi University,
5
Research Institute for Applied Mechanics, Kyushu University, 6 Institute of Geosciences, Shizuoka University, 7 Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 8 Japan Agency for Marine-Earth Science andTechnology, 9 School of Earth and Environment, The University of Western Australia
Sea level is the best indicator of the ice volume change, which plays an important role on the global climate in the Quaternary
period (e.g., IPCC AR5). The last glacial maximum (LGM), centered around 20,000 years ago, is a key period for understanding
the climate system because the global ice volume reached its maximum. However, the sea level record during the LGM is notenough to understand the relationship between the climate and ice volume changes. Here we present the sea level records during
the LGM using the new cores from the Bonaparte Gulf, northwestern Australia.
The Bonaparte Gulf is a suitable site for reconstructing the ice volume change since this region is located at far-field site:
location that is distant from the former ice sheet and the adjustment of glacio-hydro-isostatic effect is relatively small. During thecruise of KH11-1 in winter 2011, more than 20 cores were obtained from the various water depths, which provide the continuous
sea level records in the Bonaparte Gulf. In this study, over 400 radiocarbon dates of molluscs and organic matters were measured
together with total organic carbon, total nitrogen and stable carbon isotope of organic matters. Moreover, cores were investigatedby the sedimentology using a CT scan and major elemental analysis. Furthermore, the results were compared with the paleo tidal
model to assess the sea level error by the tide in this region. We suggest that sea level fall occurred at ˜21,000 years ago and theduration of the LGM is shorter than the previous studies (eg, Clark et al., 2009, Lambeck et al., 2014).

Keywords: Last Glacial Maximum, Relative Sea Level, Radiocarbon Dating, Marine Sediment Core

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MIS34-P04

Room:Convention Hall

Time:May 27 18:15-19:30

Variations in sedimentary environments around the Ryukyu Arc since 25 kyr based on
CNS elements
AMANO, Atsuko1∗ ; ITAKI, Takuya1
1

Geological Survey of Japan, AISTIn this study, we analyzed 14 C dates, grain size, and CNS element contents using sediment cores collected at the eastern edgeof the backarc and forearc of the Ryukyu Arc, and demonstrated different temporal variations in CaCO3 contents and C/N ratios
compared with previous studies of the Okinawa Trough cores. Increases in CaCO3 contents and decreases in C/N ratios, from theLast Glacial Maximum to the Holocene, in the Okinawa Trough backarc basin correspond with sea-level changes. These results
demonstrate that the sedimentary environment in the Okinawa Trough is influenced by sediment supply from mainland China,
and reveal temporal variations reflecting changes in the Yangtze River mouth that accompany sea-level changes. In contract,
CaCO3 contents of cores in this study are double those in the Okinawa Trough cores, and show an increasing trend at 7.5-6.0
cal kyr BP. Additionally, in the forearc core, the profile of CaCO3 content decreases at 11.5-8.1 cal kyr BP. These variations of
CaCO3 contents suggest that marine productivity changed with trophic conditions in sea surface. In addition, the lateral transportof terrigenous sediment by the Kuroshio and Ryukyu currents might contribute to an increased CaCO3 content by reducing theinfluence of dilution. Variations in the C/N ratio after 7.8 cal kyr BP suggest that the Kuroshio Countercurrent has varied instrength at 1-2 kyr intervals since the early Holocene, influencing the deposition of terrigenous organic matter from the Okinawa
Islands in the deeper parts of the east backarc.
Keywords: CNS elements, deposition process, sea level change, Kuroshio Current, Ryukyu Islands

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MIS34-P05

Room:Convention Hall

Time:May 27 18:15-19:30

Biogenic opal changes in the Gulf of Alaska for the last 50 kyrs
SUGA, Sei-ichiro1∗ ; ASAHI, Hirofumi2 ; KONNO, Susumu3 ; SUTO, Itsuki4 ; OKAZAKI, Yusuke3
1
4

Faculty of Sciences, Kyushu University, 2 Korea Polar Research Institute, 3 Graduate School of Sciences, Kyushu University,
Graduate School of Environmental Studies, Nagoya University

Gulf of Alaska is known as high productivity area mainly by diatoms. Diatom is a phytoplankton with biogenic frustules
and can be frequently preserved in sediments. Therefore, sedimentary biogenic opal content is used as a proxy for past diatom
productivity (e.g. Ragueneau et al., 2000). During the Integrated Ocean Drilling Program (IODP) Expedition 341 held in 2013,
Site U1418 was drilled near the continental margin of the Gulf of Alaska (58 ′ 46.6 ″ N, 144 ′ 29.6 ″ W, and 3,667 m
water depth)(Expedition 341 Scientists, 2014). At Site U1418, continuous sediments for the past 1 Myrs with foraminifera anddiatoms were recovered from five holes. Age model was constructed by oxygen isotope stratigraphy of planktonic foraminifera(Neogloboquadrina pachyderma sinistral) supported by paleogeomagnetic and microfossil datums (Asahi et al., 2014). In thisstudy, biogenic opal contents for the last 50 kyrs were measured using 120 samples from upper 60 m core depths. Biogenic opal
was analyzed by extracting with an alkaline solution (2M NaCO3 ) and molybdenum yellow colorimetric method (Mortlock andFroelich, 1989). In order to estimate paleo-flux of biogenic opal, accumulation rate (AR; g cm−2 kyr−1 ) was calculated based on
wt% of biogenic opal, sedimentary density, and sedimentation rate between age control points. Averaged biogenic opal ARs at
Site U1418 during the Marine Isotope Stages (MIS) 2 and 3 were 3.60 g cm−2 kyr−1 and 6.89 g cm−2 kyr−1 , respectively. Notethat most of Holocene sediments were not recovered at U1418. Because of low biogenic opal AR during MIS 2, it is possible
to consider that diatom productivity was low during deep glacial period. The present Gulf of Alaska is known as high nutrient
low chlorophyll (HNLC) region owing to lack of iron which phytoplankton needs in their production. It is also well-known thateolian dust increased in glacial periods and provided iron to the sea (e.g., Kohfeld and Harrison, 2001). Decreased biogenic opal
AR during MIS 2 at U1418 does not support iron fertilization scenario which expects increased productivity by iron supply fromeolian dust during glacial period. As these results, the decrease in diatom productivity may have been driven by increased light
limitation due to expanded sea-ice cover in the Gulf of Alaska (de Vernal and Pedersen, 1997).
References
Asahi, H. et al., AGU fall meeting, PP21A-1286, 2014de Vernal, A. and T.F. Pedersen, Paleoceanography 12, 821-830, 1997
Expedition 341 Scientists, IODP Exp. 341 Preliminary Report, 2014
Kohfeld, K.E. and S.P. Harrison, Earth-Sci. Rev. 54, 81?114, 2001
Mortlock, R.A. and P.N. Froelich, Deep-Sea Res. A, 36, 1415-1426, 1989
Ragueneau, O. et al., Global Planet. Change 26, 317?365, 2000
Keywords: Biogenic opal, Gulf of Alaska, Last glacial period, IODP

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MIS34-P06

Room:Convention Hall

Time:May 27 18:15-19:30

Paleoenvironmental changes during last interglacial and MIS 6 in Kuroshio region off
Honshu based on planktic foraminif
SATA, Mika1∗ ; IKEHARA, Minoru1 ; HAYASHI, Hiroki2 ; KAWAGATA, Shungo3
1

Kochi University, 2 Interdisciplinary Faculty of Science and Engineering, Shimane University, 3 Faculty of Education and Human
Sciences, Yokohama National University

Introduction
The Kuroshio Current is the western boundary current, that is a part of the North Pacific subtropical gyre. The Kuroshio plays
a main role in heat transport from the tropical ocean to the subarctic North Pacific. Paleoenvironmental changes in the Kuroshio
region during the last glacial period to the Holocene were studied during several decades (e.g., Oda and Takemoto,1992,Ujiie
and Ujiie,1999,Ikehara et al., 2009). Before the last glacial period, paleoenvironmental changes of the surface and intermediatewaters in the Ryukyu Arc region were investigated based on planktic foraminiferal analyses (Ujiie and Ujiie, 2006). However,there are no many study examples for the Kuroshio variability before the last glacial period in the south of Japanese islands.
Therefore we studied to reconstruct a paleoenvironmental changes during last interglacial and Marine Isotope Stage (MIS) 6 in
the Kuroshio region.
Sample and Methods
A long piston core MD012422 (32?08.7’N, 133?51.8’E, water depth 2737m) was obtained from the continental slope off
Shikoku and a piston core KR09-15 PC1 (33?17.7348N, 136?38.3966E, water depth 1951m) was also obtained from the Kumano
Trough. In these cores, the planktic foraminiferal assemblage was analyzed for penultimate deglaciation (Termination Ⅱ) fromthe glacial MIS 6 to the last interglacial period (MIS 5e) to reconstruct variation of the Kuroshio Current. The age model ofMD012422 was built based on the oxygen isotope stratigraphy of Globigerinoides ruber (Ikehara et al., 2006). The age model of
KR09-15 PC1 was also established based on the oxygen isotope stratigraphy of Globorotalia inflata . Each sample was washedthrough 63 µm opening sieve, prior to the drying procedure. After that each dried sample was again sieved thought 125µm
opening sieve for planktic foraminifera faunal analysis.
Result and Discussion
A total of 36 planktic foraminiferal species were identified in this study in MD012422 off Shikoku. Twenty-six species werealso identified in PC1 off Kumano. The obtained assemblage data are classified into four groups (Ujiie et al., 2003, Ujiie andUjiie, 2006), which are related with surface water conditions. In this study, we focused on the Kuroshio species, which arecomposed of Pulleniatina obliquiloculata and Neogloboquadrina dutertrei . The abundance of Kuroshio species showed high inboth sites for MIS 5e. But, their abundance decreased off Kumano for MIS 6. Therefore we interpreted that the Kumano Troughregion was not influenced by a warm Kuroshio during the penultimate full glacial MIS 6. For the last interglacial MIS 5e, theKuroshio was flowing through the similar position with modern.

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MIS34-P07

Room:Convention Hall

Time:May 27 18:15-19:30

Change in monsoon climate and lake-water-level recorded in middle Pleistocene PaleoKathmandu Lake sediments
SETOGUCHI, Ryoko1∗ ; FUJII, Rie1 ; SAKAI, Harutaka1
1

Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University

In order to reconstruct terrestrial Indian monsoon record during the MPT (Middle Pleistocene Transition) and to clarify thecauses of lake-water-level changes, pollen and other microfossils analyses were conducted on the lacustrine sediments in thesouthern Kathmandu basin on southern slope of the Central Himalaya.
We reconstructed continuous record of vegetation and climate changes from ca. 1000 ka to 500 ka on the basis of pollen
analysis of a 114-m-long drill core at Champi. In addition, changes in ratio of other proxy: sponge spicules, phytoliths and plantfragments are analyzed and compared with the reconstructed climatic record
On the basis of changes in relative abundance and assemblage of fossil pollen, nine pollen zones are constructed. Pollen zone 9,
7, 5 and 3 indicate cold and dry climate and zone 8, 6, 4 and 2 indicate warm and wet climate. Cold index (Abies and Tsuga ) anddry index (Artemisia and Chenopodiaceae) increase during period of cold climate after zone 7. Cold index (Abies and Tsuga )and dry index (Gramineae) increase much more under cold climate after zone 5 and at the same time, ratio of arboreal pollen
begins to cyclically change. A comparison of pollen zones with MIS (marine isotope stage) and magnetostratigraphic study
indicate that pollen zones from 8 to 2 correspond to MIS 27-15. The pollen diagram suggests that climate of the Kathmandu
Valley became cool and dry at 900 and 700 ka (pollen zone 7 and 5), and cyclic climatic change started at 700 ka. These changes
seem to correspond to abrupt increase and cyclic changes of global ice volume in the MPT.
Sponge spicule decreases its ratio during the period of dry climate, therefore it could be ascribed to shrinking of habitat ofsponge due to the lowering of lake-water under dry climate. Abrupt and rapid decrease of sponge spicule and diatom at around
50 m in depth suggests rapid lowering of lake-water-level for a moment. This change possibly is caused by drain of lake waterowing to occasional break of the dam, because the pollen zone 2 indicates warm and wet climate which implies increase oflake-water-level.
Keywords: Indian monsoon, Kathmandu basin, lacustrine sediments, pollen analysis, sponge spicle

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MIS34-P08

Room:Convention Hall

Time:May 27 18:15-19:30

Reconsideration of the existence of marine clay beds in KD-1 and KD-2 drilling cores in
Kyoto Basin
ISHIKAWA, Naoto1∗ ; TAKEMURA, Keiji2
1

Grad. EHS, Kyoto Univ., 2 Beppu. Geo. Res. Lab., Kyoto Univ.

Research programs including seismic reflection surveys and deep drillings were carried out at the Kyoto Basin between 1998
and 2002 for clarifying underground structure of the basin. Deep drilling cores taken at three sites, KD-0 in the southern part ofthe basin (Ogura-ike), KD-1 in the central part (Hokotate Park south of JR Kyoto station) and KD-2 in the northern part (Nijo-joCastle), were composed of thick strata of the Osaka Group and Pleistocene terrace deposits. Marine clay beds, the key beds in
the Osaka Group, were identified at five horizons in KD-0 and KD-1 cores (Ma3, Ma4, Ma5, Ma6 and Ma9 beds) and three in
KD-1 core (Ma5, Ma6 and Ma9 beds) according to the color of sediments, results of fossil and pollen analyses and stratigraphic
correlations of volcanic ash layers (Kyoto City, 2003). Kitani and Kamo (2010) reconsidered the stratigraphy of KD-0 core, andidentified 13 marine clay beds in the Osaka Group (Ma0, Ma0.5, Ma1, Ma1.3, Ma2, Ma3, Ma4, Ma5, Ma6, Ma7, Ma8, Ma9 andMa10 beds) and one marine clay bed in terrace deposits (Ma12 bed).
In order to reconsider the existence of marine clay beds in KD-1 and KD-2 cores, we performed measurements of electric
conductivity (EC) and pH of stirred clayey sediments in water on 15 mud layers in KD-1 core and 14 layers in KD-2 core basedon the method of Yokoyama and Sato (1987). In KD-1 core, samples of marine clay beds identified in Kyoto City (2003) showed
high EC and low pH values, and were regarded as marine sediments based on the criteria of Yokoyama and Sato (1987). A mudlayer above Ma9 bed was also found to show high EC and low pH values, and marine diatom fossils were found in the mud
sample by smear slide observations. The layer may be correlated to Ma10 bed. In KD-2 core, samples of Ma5 and Ma6 beds hadhigh EC and low pH values. Other samples including that of Ma9 bed had low EC and higher pH of 6-7, and were regarded as
fresh water sediments. It may be implied that the sea water invasion occurred at the formation age of Ma10 bed (about 0.34Ma)
in the central part of the Kyoto Basin, and that the northern part has been under the fresh water environment after the formation
age of Ma6 bed (about 0.62Ma).

Keywords: Kyoto Basin, marine clay bed, Osaka Group

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MIS34-P09

Room:Convention Hall

Time:May 27 18:15-19:30

The response of terrestrial climate variations in the orbital cycles based on a marine pollen
records
SUGAYA, Manami1∗ ; OKUDA, Masaaki2 ; OKADA, Makoto3
1

Graduate school of Sci. and Eng. Ibaraki University, 2 Natural History Museum and Institute of Chiba, 3 Department of science,
Ibaraki University
A pollen analysis of drilled marine core, that is effective for long-scale and continuous paleoclimate reconstruction because
marine sediments have direct d18O-based timescales, which is absent in terrestrial materials. In this study, we carried out pollen
analysis to the core C9001C drilled off Shimokita Peninsula, for paleoclimate reconstruction and compose pollen stratigraphyduring the Brunhes paleomagnetic chron. As a result, during the interglacial periods is dominated by cool temperate pollen
assemblages that is similar to the present-day Shimokita vegetation. In contrast, during the glacial periods is dominated bysubarctic pollen assemblages, and the weak glacial periods or the transition periods of interglacial to glacial dominated by coolmixed pollen assemblages. In order to extract more detailed paleoclimate information we apply the modern analogue techniqueto our pollen records. As a result, paleoclimatic parameters suggested two different variations of paleo-temperature and paleoprecipitation, these are good correlates glacial-interglacial cycles and summer insolation variations, respectively.
Keywords: pollen, paleoclimate reconstruction, marine core

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MIS34-P10

Room:Convention Hall

Time:May 27 18:15-19:30

Paleolimnological changes of Lake Maruwanminami-ike and Maruwan-Oike in Soya Coast,
East Antarctica during the Holocene
KANG, Ijin1∗ ; KASHIMA, Kaoru2 ; SETO, Koji3 ; ITO, Keisuke4 ; HONDA, Eisuke4 ; TANI, Yukinori5 ;WATANABE, Takahiro6 ; NAKAMURA, Toshio7 ; IMURA, Satoshi8 ; MATSUMOTO, Genki I.9
1

Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 2 Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 3 Research Center for Coastal Lagoon Environments, Shimane
University, 4 Graduate School of Studies in Human Culture, Otsuma Women’s University,, 5 Institute of Environmental Sciences,
University of Shizuoka, 6 Graduate School of Environmental Studies, Tohoku University, 7 Center for Chronological Research,
Nagoya University, 8 National Institute of Polar Research, 9 School of Social Information Studies, Otsuma Women’s University
The Antarctic Ice Sheet is the largest mass of ice on Earth. In the Antarctic Ice Sheet, there are huge amount of freshwater,
approximately 60 % of all freshwater on earth. Furthermore, the present Antarctic Ice Sheet contains enough water to raise sea
level almost sixty meters, so that only a small change in their volume would have a significant effect to the earth. Antarctic
coastal lakes are invaluable archives of paleoclimate and paleoenvironment changes due to the retreat of Antarctic Ice Sheet. In
Soya Kaigan (Coast) of Lutzow-Holm Bay region, there are many coastal lakes in ice-free areas. Hydrological changes of coastallakes located below 20 m ASL from marine to freshwater environments are result from the recession of glaciers and subsequent
isostatic uplift.
In this study, we estimate the Holocene environmental change of Soya Kaigan inferred from the analyses of a lake sedimentcore of Lake Maruwan-Oike (Mw4C-01) and Maruwanminami-ike (MwS4C-01) in Rundvagshetta ice-free area. We conductedRadiocarbon dating and Elemental Analyses by Matsumoto et al. (in prep) to carry out Total Carbon, Total Organic carbon,
Total Nitrogen and Total Sulfur. In addition to these results, I clarify assemblage changes of fossil diatoms in the sediment core
Mw4C-1 using a characteristic of diatoms living apart by water conditions such as salinity. From the results of diatom analyses
and previous analyses, we will report about the Holocene hydrological and environmental changes in detail.

Keywords: Antarctic coastal lakes, Paleoenvironment, Paleolimnology, Diatom analysis, the Holocene

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MIS34-P11

Room:Convention Hall

Time:May 27 18:15-19:30

Heinrich events and activities of winter monsoon recorded in bottom sediment of Lake
Inawashiro
INOUCHI, Yoshio1∗ ; MAURA, Kousei2 ; YAMADA, Kazuyoshi3
1

Faculty of Human Sciences, Waseda University, 2 School of Human Sciences, Waseda University, 3 Museum of Natural andEnvironmental history, Shizuoka
Coastal areas along the Japan Sea are regarded as second largest rainy area in Honshu Island. Relatively heavier rainfall inthese areas is caused by heavy snowfall during winter thus named heavy snowfall area by Heavy snowfall area special measureslaw. In order to know future trend of this snowfall, we selected Lake Inawashiro of Fukushima prefecture, Tohoku region as amonitoring site where melted snow from surrounding mountains flows in during spring. We analyzed grain size of 5 millimeter
thick sediment at 2.5 centimeter interval which were drilled at the central part of the lake with 28 meter length. The sediment iscomposed chiefly of thinly bedded alternation of light and dark layers which have several millimeters thickness and is intercalated
by 15 tephra layers and 30 pairs of light and dark layers with several centimeters thickness. We made an age model using datesof widespread tephras and radiocarbon ages of sediments and converted depths of sediments into ages. We analyzed frequencyof grain size change with REDFIT method. The result shows 7000 year cycle from 45ka to 10ka. In addition, dates of maxima
of grain size well correlates with those of Heinrich events. Also those dates well correlate with those of ice rafted debris weightin Japan Sea sediment. Grain size profile shows reverse grading at the lower part of thick light and dark layers and normal
grading at the upper part. In addition, light colored lower parts are rich in periphyton diatoms living preferably in acidic water.
These results show that sediment in lake Inawashiro is intercalated by many flood sediments. Based on the results that ages ofmaxima in grain size profile well correlate with those of Heinrich events and that event sediments are flood sediment origin, we
concluded that abrupt cooling made winter monsoon stronger and caused heavy snowfall along Japanese island and large floods
by melting snow. Report of IPCC WG1 does not suppose abrupt cooling during this century. Consequently, global warming is
expected during this century. In that case, winter monsoon will be weakened and it will be apprehensive that water resources forrice planting and hydroelectric power generation will be decreased.
Keywords: Heinrich events, winter monsoon, lake sediment, drilling core, climate change

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MIS34-P12

Room:Convention Hall

Time:May 27 18:15-19:30

Heinrich events and activities of winter monsoon recorded in bottom sediment of Lake
Biwa
INOUCHI, Yoshio1∗ ; YAMADA, Kazuyoshi2 ; OKAMURA, Makoto3 ; MATSUOKA, Hiromi3 ; SATOGUCHI, Yasufumi4
1
4Faculty of Human Sciences, Waseda University, 2 Museum of Natural and Environmental history, Shizuoka, 3 Kochi University,
Lake Biwa Museum

Coastal areas of Honshu Island along the Japan Sea have heavy snowfall and second rainy areas to coastal areas along the
Pacific Ocean. This heavy snowfall supplies large volume of melting water and is used for rice planting and become energy
source for hydroelectric power generation. Snowfall in winter is firmly related to winter monsoon which blows over the Japan
Sea. Consequently, monitoring snowfall can lead to monitoring the intensity of winter monsoon. In order to clarify historicalwinter monsoon intensity change, we selected Lake Biwa where Mount Ibuki that has heavy snowfall is very near. We carriedout chemical analysis of bottom sediment of 18 meters long piston cored at the central part of Lake Biwa. The sediment consists
chiefly of muddy sediment and is intercalated by some tephra layers. Depths of the sediment were converted into ages by theage model based on the age of wide spread tephras and radiocarbon dates of sediment. The result shows that frequency of 6ky ispresent in the total carbon content profile and that of biogenic silica. Ages of minima of total carbon content together with thoseof total carbon/total nitrogen ratio correlates well with those of Heinrich events. Calcium content profile shows 7ky frequency
and minima of calcium content correlate with Heinrich events. On the other hand, phosphorus content shows the same frequency,
however, maxima of this content correlate with those of Heinrich events. Among these profiles, that of phosphorus well correlateswith that of lake level change which is shown by sand content profile obtained from drilling sediment near the river mouth of Echi
river. Phosphorus content is lower during higher lake level. This result shows opposite tendency that manganese and phosphorus
contents are higher during high lake level. Based on those results following sedimentation model is proposed. During the periodsof abrupt cooling, snowfall was heavier than other periods. At the time of cooling, large volume of melted snow transports
calcium rich detritus materials in spring which are supplied from Ibuki mountains those composed mainly of limestone. On theother hand, production of organic materials decrease during cold periods and transportation of organic materials also decreases.
Furthermore, because chemical weathering on land is weakened, transportation of phosphorus and manganese becomes smaller.
Therefore, calcium content shows normal correlation to snowfall volume whereas that of phosphorus shows reverse correlation.
Based on the fact that the ages of this kind of sedimentation correlate with those of abrupt cooling, activities of winter monsoon
was stronger at those periods and snowfall became larger which made lake level higher than usual owing to large volume of
melting snow.
Keywords: Heinrich events, winter monsoon, lake sediment, drilling core, climate change

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MIS34-P13

Room:Convention Hall

Time:May 27 18:15-19:30

Continental response to millennial-scale climate change during the last glacial to Holocene
periodIKEDA, Hisashi1 ; SHIBATA, Kenji2 ; MURAKAMI, Takuma2 ; SAITO-KOKUBU, Yoko2 ; KATSUTA, Nagayoshi1∗
1

Faculty of Education, Gifu Univ., 2 Japan Atomic Energy Agency

Here we report analytical results of minor elements in Lake Baikal sediment which contain environmental response to theclimate changes during the last 33 kyr.
Keywords: Conitnental interior of Asia, Lake Baikal, Terrestrial environmental system, Minior elements, Uranium, Climatechanges

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MIS34-P14

Room:Convention Hall

Time:May 27 18:15-19:30

Relationship between early summer precipitation in Japan and the El Nino-Southern Oscillation over the past 400 years
SAKASHITA, Wataru1∗ ; YOKOYAMA, Yusuke1 ; MIYAHARA, Hiroko2 ; YAMAGUCHI, Yasuhiko T.3 ;AZE, Takahiro1 ; OBROCHTA, Stephen4 ; NAKATSUKA, Takeshi51

Atmosphere and Ocean Research Institute, The University of Tokyo, 2 College of Art and Design, Musashino Art University,
Department of Earth and Planetary Science, The University of Tokyo, 4 Faculty of International Resource Sciences, Akita University, 5 Research Institute for Humanity and Nature

3

The El Niño-Southern Oscillation (ENSO) potentially influences East Asian Summer Monsoon (EASM) rainfall, but the relatively short instrumental rainfall record hinders the progress of a longer-term understanding of this relationship. To partiallyovercome this issue, we reconstruct precipitation from tree-ring oxygen isotopes (δ 18 O) in central Japan from AD 1612 to 1935.
Our results show that tree-ring cellulose δ 18 O is significantly correlated with May-June (MJ) rainfall in central Japan, allowing us
to examine the relation between the EASM summer rainfall and ENSO during the past 400 years. Time- and frequency-domaincomparison of the tree-ring δ 18 O record and recent ENSO reconstructions show a common high-frequency (3-8 year) variability
that characterized the mid-17th, late 18th and late 19th centuries. Similar analyses of instrumental MJ precipitation and several
ENSO indexes during the 20th century reveal that this high-frequency oscillation reappeared from AD 1980. Comparison of
ENSO and Pacific Decadal Oscillation (PDO) indexes reveals that the ENSO-EASM relationship is strong when ENSO varianceis high, and the PDO phase may modulate the ENSO-EASM relationship over the past four centuries.

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MIS34-P15

Room:Convention Hall

Time:May 27 18:15-19:30

Oxygen isotopic records of stalagmite OT02 collected Gujo City, Gifu Prefecture
KANO, Akihiro1∗ ; MORI, Taiki1 ; SONE, Tomomi2 ; SHEN, Chuan-chou3 ; KASHIWAGI, Kanji4
1

Kyushu University, 2 Marine Works Japan, 3 National Taiwan University, 4 Toyama University

A 13-cm-long stalagmite OT02 from Gujo City (central Gifu Prefecture) recorded climatic information of two separated
periods of Marine isotopic stage 3 (MIS-3) and Holocene. Oxygen Upper and lower parts of the stalagmite differ in oxygenisotopic values; the lower MIS-3 part are 0.5-1.0 permil higher than the upper Holocene part. This difference is comparable toone that has been reported from stalagmites in south China, revealing that the Gifu stalagmite was formed under the influence
from East Asian summer monsoon (case 1). However, meteoric water samples collected at a reference site (Ogaki City) clearly
indicate seasonality in the oxygen isotope values. Meteoric waters in winter generally record low isotopic values, and the recordsof OT02 can be the change in the winter proportion of meteoric water (case 2). OT02 is unique in terms of different periodicity
recorded in the oxygen isotopic composition; ˜650-yr cycles in the Holocene interval and millennial-scale changes in the lower
MIS-3 interval. The Holocene cycle are most likely responded to the swell of solar activity that affected to proportion of winterrainfall (case 2). In contrast, the millennial-scale changes in the lower OT02 are likely associated with Dansgaard-Oschger (D-O)
events. Eight bands of low oxygen isotope during a period of 55-35 ka follow the spacing of the dark layers in deep-sea sedimentsfrom the Japan Sea. In each cycle, the stalagmite increases transparency to the upward, and suddenly becomes darker at the baseof the upper cycle. Similarly, oxygen isotopic values gradually increase in each cycle and rapidly decrease at the base of theupper cycle. Although some of millennial changes in the Gifu stalagmite indicate D-O cycles cannot be seen in the Greenland
ice sheet, our records suggest that the central Japan was under the influences of D-O cycles. Oxygen isotope records of the lower
OT02 are consistent to case 1 interpretation rather than case 2. Assuming this, it became dry during a gradual cooling period andshifted wet with an abrupt warming.

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MIS34-P16

Room:Convention Hall

Time:May 27 18:15-19:30

Oxygen isotopic records of the stalagmite KA01 from Kiriana in Mie Prefecture, Japan
MORI, Taiki1∗ ; KANO, Akihiro1 ; SONE, Tomomi2 ; SHEN, Chuan-chou3 ; KASHIWAGI, Kenji4
1

Kyushu University, 2 Marine works Japan, 3 National Taiwan University, 4 Toyama University

It has been considered that the stalagmite oxygen isotope is reflected from rainfall intensity of the water reserve area. Especially, the records from south China have been treated as proxy of the intensity of the East Asian Summer Monsoon (EASM).
However, some resent studies suggested that the Chinese stalagmite records rather indicate the change in proportion of the Indian
Monsoon from southwest and the Asian Monsoon from southeast. In Japanese Islands located at the east margin of the Asian
Monsoon area, the rainfall during summer is almost exclusively brought from EASM. Thus, the EASM intensity was more directly recorded in the Japanese stalagmites than in the Chinese stalagmites.
We studied the stalagmite KA01, a 35-cm-long specimen that has been formed from 12.6 ka to 1.3 ka. KA01 and some Chineserecords share similar features, such as higher values around 12 ka, depressed intensity during 7-9 ka, and the trend change fromincreasing to decreasing at 2.8 ka. However, KA01 exhibits smaller amplitude of the isotopic change than the Chinese specimens. The reduced amplitude of KA01 was likely attributed to the shorter distance of the vapor transportation, which reflectedon the condensation ratio. Thus, our isotopic profile of KA01 is probably more faithful record of the EASM and therefore can bevaluable for considering the Holocene evolution of the East Asian climate system.

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MIS34-P17

Room:Convention Hall

Time:May 27 18:15-19:30

Observation of fluorescent laminae structure in stalagmites for lamina counting and resultsof U-Th dating
HISAMOCHI, Ryo1∗ ; WATANABE, Yumiko1 ; ABE, Yuji2 ; NAKAI, Shun’ichi3 ; TAGAMI, Takahiro1
1

Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, 2 Taga Town Museum, 3 Earthquake
Research Institute, University of Tokyo
Stalagmites are recognized as a powerful tool to reconstruct paleoclimate. However, it is difficult to date stalagmites. Dating
methods of stalagmites are mainly U-Th dating and laminae counting. U-Th dating sometimes shows stratigraphic inverted
results, whereas laminae counting has a problem that we have little information about the annual laminae (for example, whenand how they are formed? or what they look like?). In this study, I analyzed stalagmite samples collected at Taga Mine, Shiga
Prefecture, Japan. I try to reveal the characteristics of laminae in stalagmites and investigate U-Th age.
Stalagmite samples have fluorescent laminae, which can be divided into three types: lamina A, lamina B and wavy lamina.
Lamina A is normal type, lamina B is relatively ambiguous lamina and wavy lamina is of wavy shaped. According to FE-SEM
image, both lamina A and wavy lamina consist of small particles (diameter is several 10˜100nm). Lamina B can not be observed
by FE-SEM probably because particles smaller than 10nm can not be resolved due to polishing scratches. Wavy lamina has manygaps filled with mud. This indicates that wavy lamina is formed when mud covers the stalagmites and prevents calcite growing.
In previous researches, main component of fluorescent laminae may be fulvic acid. Thus the small particles of FE-SEM images
may be fluvic acid. To confirm this, I use micro-Raman spectroscopy, micro-FT-IR, SEM-EDX. However, all analyses can notreveal what the small particles are, probably because the small particles are too small to analyze. The result of EPMA indicatesthat laminae A contains mud. However, the strength of laminae A is not proportional to that of Si and Al peaks, hence Si and Al
are not Principal component of lamina A.
I dated stalagmite samples by U-Th dating and I got stratigraphic inverted results: the upper parts of stalagmites are older thanthe lower parts of them. I calculate the quantity of contamination substance in stalagmite which can influence the U-Th age.
In consequence, the stratigraphic inverted results of U-Th dating are probably because of contaminations by mud. On the other
hand, humic substances in stalagmites possibly influence U-Th dating.

Keywords: speleothem, lamina, paleoclimate

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MIS34-P18

Room:Convention Hall

Time:May 27 18:15-19:30

Cave air monitoring and chemical analysis of drip water at Inazumi cave, Oita, JapanSHINDOH, Tatsuro1∗ ; WATANABE, Yumiko1 ; MISHIMA, Taketoshi1 ; OHSAWA, Shinji1 ; TAGAMI, Takahiro1
1

Earth Planetary Science, Graduate school of Science, Kyoto University

10 month cave air monitoring and chemical analysis of drip water were conducted at Inazumi cave, Oita, Japan, from February
to December, 2014, to understand the processes and mechanism of recording paleoclimate in stalagmite. Cave air CO2 wasmeasured for the cave monitoring, and EC, pH, HCO3 − and Ca2+ were measured for chemical analysis of drip water.
Special sampling techniques were designed for two sampling sites, SS2 and SS3, to highlight the relationship between cave
air CO2 and drip water chemistry. At SS2, the drip waters, before and after hitting on three handrails arranged in tandem inlimestone cave (SS2-U, -M2, -M3 and -L, respectively), were sampled. At SS3, the drip waters, befor contacting with the cave
air (BCWA) and after hitting on the artificial stalagmite, were sampled (BCWA, SS3-U, -M, -L, respectively).
At SS2, as the drip water hit on the handrails, HCO3 − , Ca2+ and EC showed decreasing trend respectively and this trend
became significant during winter when the cave air CO2 was low. Only pH was negatively correlated with other drip waterparameters the above. This suggests that the two conditions, 1) the cave air CO2 is lower and 2) water film gets thinner as thedrip water hits on the handrails, promote more CO2 degassing and CaCO3 precipitation.
At SS3, HCO3 − and Ca2+ between BCWA and the drip water after contacted with the cave air showed almost the same
concentration during summer, high cave air CO2 season, however, marked significant margin between them during winter, lowcave air CO2 season. This result suggests that once drip water contacts with lower cave air CO2 , more CO2 degassing and CaCO3
precipitation are promoted.
S.I.cc, standing for Saturation Index of Calcium Carbonate, and 4pCO2 , the difference of partial pressure of drip water(pCO2−dripwater ) and of cave air (pCO2−caveair ), were calculated if CO2 degassing and CaCO3 precipitation takes place or not.
S.I.cc showed positive value at SS2 and SS3 during almost all monitoring periods, indicating CaCO3 is produced almost all thetime. However, 4pCO2 showed frequently negative value at SS2 and SS3, indicating that CO2 is not degassed from the drip
water and the following CaCO3 precipitation is not taken place and that most of drip water sampled already degassed CO2 .
This research implied that CO2 variation is a main forcing factor to control HCO3 − and Ca2+ , main components in drip water
to form CaCO3 -made-laminae used for reconstructing paleoclimate; however, the calculation of 4pCO2 showed that CaCO3
would not be produced from drip water. To solve the contradiction, another approach such as development of new sampling
method will be necessary.
Keywords: Paleoclimatology, Stalagmite, drip water, cave air monitoring

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MIS34-P19

Room:Convention Hall

Time:May 27 18:15-19:30

Characterization of Aeolian Dust, Sediment, with SEM-EDS Automated Particle Analysis
MUTOU, Hitomi1∗ ; SHIMADA, Aiko2
1

JEOL Ltd., 2 JEOL RESONANCE Inc.

SEM-EDS automated particle analysis, which is the automated particle analysis combined with a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS), is a very powerful method to characterize particle mixtures ofseveral different substances. With this method, we can analyze a large number of particles, more than 10,000 particles one byone, directly. The analyzed data, the shape and size as well as the composition of each individual particle, are stored for thecharacterization of the mixtures and classified into about some groups with similar composition, same minerals, and so on automatically. We have successfully applied this method to the characterization of a few rocks and sediments by using this method[1], [2] and [3]. Detailed analysis of rocks and sediments would give important information on mountain uplift, river contention
and erosion process. In this study, we extend our efforts to aeolian dusts and sediments, for example Beijing Urban Aerosols andGobi Kosa Dust. They were purchased from National Institute of Environmental Studies (NIES), which distributes them as environmental certified reference materials. Classification was made of their composing particles. Furthermore, statistically averaged
concentrations of elements obtained in the present study were compared with those listed in the NIES document. For example,
in Beijing Urban Aerosols, we analyzed 30,000 particles and classified by their composition. The average of the particles size is
6 µm and the distribution of the particle size is 1- 40 µm. These particles contained quartz, feldspar, gypsum, calcite and othermaterial. In addition, a lot of hydro sulfates and sulfides were detected with clay minerals. In the presentation, we will show
more detailed descriptions of the correlation between Beijing Urban Aerosols and Gobi Kosa Dust, and other sediment analysis
results.
[1] H. Muto, A. Shimada, 2014, SEM-EDS Automated Particle Analysis of Mineral Compositions of Rocks, the Japan Geoscience Union Meeting 2014.
[2] H. Muto, A. Shimada, 2014, Characteristics of Granitic Rocks around Lake Biwa with SEM-EDS Automated Particle
Analysis and ESR Signals, the 2014 annual meeting of Japan Association Mineralogical Sciences.
[3] H. Muto, A. Shimada, 2014, SEM-EDS Automated Particle Analysis of Mineral Compositions of River Sand, the annual
academic conference of the Japan Society of Microscopy 2014.

Keywords: Sediment, Aerosol, SEM, EDS, Particle analysis

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MIS34-P20

Room:Convention Hall

Time:May 27 18:15-19:30

A chronostratigraphic study of the upper Anno Formation, Awa Group, distributed in the
middle part of the Boso Peninsula
HANEDA, Yuki1∗ ; OKADA, Makoto2
1

Graduate School of Science and Engineering, Ibaraki University, 2 College of Science, Ibaraki University

Since the Awa Group, distributed in the central Boso Peninsula, has a good continuous exposure, abundant microfossils andmany intercalated treiceable tephra beds, a lot of stratigraphic studies have been conducted so far. Okada et al (2013) reported
magnetostratigraphy of the upper Anno Formation exposed along the Minato and Shikoma rivers, which concluded that theMammoth reversed subchronozone (3.207-3.330Ma) and the Gilbert-Gauss boundary (3.596Ma) were recognized at the horizonof between the An155 and An157 tephra beds and at the horizon near the An127 tephra bed, respectively. However, sampling
resolution, which is about 10m in the stratigraphic interval at the Shikoma river route, is not sufficient to deny a possibility thatthe subchronozone is recognized as the Kaena reversed subchronozone (3.116-3.032Ma). We therefore conducted resamplingwith a higher resolution in order to refine the magnetostratigraphy with a better temporal resolution.
For paleomagnetic, rockmagnetic and oxygen isotopic measurements, we sampled 1-5 mini-cores and sedimentary rocks with
about 300g by dry-weight at 117 sites, respectively. The samples were taken downward from the horizon just below the Kurotaki
unconformity in Shikoma river route.
We performed alternating-field demagnetization (AFD) and thermal demagnetization (ThD) in order to extract primary components from the specimens. Additionally, we carried out a magnetic hysteresis parameter analysis and a thermomagnetic analysis
to detect rockmagnetic parameters. The results exhibit that most specimens consist pseudo-single domain magnetites as themagnetic carrier of natural remanent magnetizations. Characteristic remanent magnetizations (ChRMs) calculated from bothof AFD and ThD results did not pass the reversal test, indicating that secondary magnetization components are not able to be
removed completely with the both demagnetization technics. However, we judged that the ChRMs from ThD would be reliable
to evaluate the polarities, since the secondary components are quite small. Accordingly, we confirmed polarity boundaries at
depths of 96-98.4m, 22.5-26.6m and 11.4-14.7m. Because the polarity boundary at the deepest site is near the An127 tephra bed
as well as the previous study, it is compared to the Gilbert-Gauss boundary. The polarity boundaries at depths 22.5-26.6m and11.4-14.7m correspond to the upper and lower boundaries of the Mammoth reversed subchronozone, respectively, since there isno other polarity reverse from the deepest polarity boundary to the middle polarity boundary. Sedimentation rate between the
Gilbert-Gauss boundary and the lower boundary of the Mammoth reversed subchronozone, and between the lower and the upperboundaries of the Mammoth are evaluated as about 27cm and about 9cm, respectively. The significantly decreased sedimentation
rate observed during the Mammoth subchron corresponds to the horizon between the An155 and An157 tephra beds. Nakajima
and Watanabe (2005) reported that the horizon between the An155-2 and An156-4 tephra beds was eroded by a slump at the
Shikoma river route. We consider that the significantly decreased sedimentation rate attributes a hiatus due to erosion by slump.
We, hence, plan to extract foraminifers from sedimentary rock samples from the same sites of paleomagnetic mini-cores, andmeasure oxygen isotopes. After that, we are going to discuss chronostratigraphy using oxygen isotope stratigraphy and magnetostratigraphy.
Reference
Okada M, Umihoko T, and Yoshioka T, 2013, Magnetostratigraphy of upper part of the Anno Formation, the Awa Group, in
the Boso Peninsula, Japan. Abstr. 120th Ann. Meet. Geol. Soc. Japan.
Nakajima T, and Watanabe M, 2005, Geology of Futtsu District. Quadrangle Ser. Scale 1 : 50000, Tokyo (8), 85, Geol. Surv.
Japan, AIST, 102p.

Keywords: Magnetostratigraphy, Oxygen isotope stratigraphy, Chronostratigraphy

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MIS34-P21

Room:Convention Hall

Time:May 27 18:15-19:30

On the glacial carbon reservoir in the deep-sea
OKAZAKI, Yusuke1∗
1

Kyushu University

Numbers of studies has been performed to seek the glacial carbon reservoir in the deep-sea. Radiocarbon age offset between
co-existing benthic and planktic foraminifers is widely used to estimate ventilation rate of the glacial deepwater. However,reconstructed results in previous studies were divided into two groups: comparable to the present and much older than thepresent. The discrepancy is caused by sediment disturbance inferred from major change in depth-age curve and estimation ofregional marine reservoir age. These suggest an importance of primary information on sediment core sample and radiocarbon
data.
Keywords: Glacial period, Carbon reservoir

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