List of Dissertation Abstract （Environment and Natural Sciences Earth and Ecology Course）
Name

Supervisor

Ikuya

YukiraWATANABE

MOCHIDA

Akira

Ryuuiti

Furusawa

MajimaTitle

Abstract

Effects of location
environment and deer in theQuercus crispula Blumedominant secondary forest to
the distribution of seedlingsand saplings

In order to exert the function of environmental conservation, it is important to reproduce thetreeless land by natural forces. In order to consider the natural regeneration, it was investigatedwhether the seedlings and saplings are growing in any habitat. Emerged the number ofindividual seedlings and saplings as explained variable, the habitat of 5 factors and deer
population as an explanatory variable, it was performed a multiple regression analysis. As aresult of the analysis, the influence by the habitat and the deer had been different in seedlings
and saplings between the same species.

Planktonic foraminifera
biostratigraphy of theCenozoic of the northwesternpart of the Leyte Island,
Philippines

I studied a planktonic foraminifer biostratigraphy of Cenozoic marine strata at northwestern
coastal area of Leyte Island, Philippines, using a total of 24,000 specimens that consist of
more than 300 specimens of each 86 sampling horizon. I identified 40 species and dated 4.50
to 4.20 Ma in the lower stratigraphic horizon and 2.58 to 1.30 Ma in the middle and upperhorizons. In the middle horizon, older fossils are coexisted with younger ones, probably due tothe reworking contaminations by slumping that have been evidenced by field observations.

It is important that prevention of Sicyos angulatus L at the water's edge, for a measure ofHiroyuki

YukiraIGAKI

MOCHIDAflourishing the plant. Sicyos angulatus L intrude into the location where meets three
Early habitat and expanding
distribution of the alien plant, conditions. Firstly, vegetation is Miscanthus sacchariflorus community, Artemisia indica
Sicyos angulatus L, in riverbed community or Ambrosia trifida community. Secondly, relative elevation is low. Thirdly, morethan 20 % of ground is less than 2 mm.

Tomohiro

RyuichiIZUMIMAJIMA

ToshikiRyuichi

ICHIMURA

MajimaDepositional environments ofthe Upper Ikego Formation ofthe Miura Group and theLower Urago Formation of theKazusa Group (PliocenePleistocene), exposed on thenorthern Miura Peninsula,Japan.

I studied depositional environments of the upper part of the Ikego Formation (the MiuraGroup) and the lower part of the Urago Formation (the Kazusa Group) (upper Pliocene –lower Pleistocene), exposed on the northern Miura Peninsula.
I measured the orientations of the sole marks and the imbricated structures of sandstonegrains within the five sediment gravity flow deposits. I interpreted the sole marks as flute ones
and obtained paleocurrents from west to east and from south-southwest to north-northeast.
Imbricated fabrics show paleocurrents from south-southwest to north-northeast. These results
are concordant well with a proximal (southwest) and distal (northeast) relation obtained in theprevious studies.

Depositional environments ofthe Imaizumi Sandstone andConglomerate Member(Lower Pleistocene) of theNojima Formation of theKazusa group exposed at thenorthern Miura Peninsula

I studied stratigraphically and sedimentologically the Imaizumi Sandstone and Conglomerate
Member of the Urago Formation, exposed at the northern Miura Peninsula. The Member iscomposed of a submarine fan system, judging from shingle overall coarsening and thickening
upward trend of beds, and is interpreted to have been progradated from south to north, basedon the paleocurrent analysis. In the lower and middle horizons of the Member, small
progradated lobes are well developed and interpreted as a mid-fan setting. In the upperhorizon, main channel systems are overlain on the lobe systems of the mid-fan and isinterpreted as upper fan deposits. The palaeomagnetic and tephra-chronologic studies in thestudy area indicate that the Member had been deposited between 2.5 Ma and 1.97 Ma.

AkaneShuichiOHIRA

KODAIRAAyaYukiraKAWASEMOCHIDA

Sesimic structure of theoceanic Moho and deep
oceanic lithosphere atsoutheast of the Shatsky Risein the Northwestern Pacific

To understand formation and alternation processes of the oceanic plate, I processed an activesource reflection/refraction data acquired along a long profile at southeast of the Shatsky Risein the northwestern Pacific. Various reflection characters of the oceanic Moho on seismicreflection section indicate that the sharp Moho formed at a fast-spreading center wasalternated by the off-ridge magmatism. Analyses on wide-angle reflections on records ofocean bottom seismometers show that within the current lithosphere there are low velocity
patches associated with past lithosphere-asthenosphere boundaries.

To clarify why non-palatable species were debarked by deer, we established seven study sites
in the Southeast areas of Yatsugatake Mountains and examined the intensity of bark stripping,grazing of Sasa nipponica, snow depth, inclination of site slope, and frequency of habitat use
Bark stripping of oak (Quercusby sika deer. At the site with steep slope on the Southwestern side of the Mountains, snow
crispula Blume) by sika deer
depth was shallower and the frequency of habitat use by sika deer was higher. It was deemedin relation to locational
that, with the abundant sunshine falling on the slope, snow depth became shallow and the sitefactors.
offered habitats suitable for deer in winter. The findings suggest that, deer density become
high at the slope with less snow accumulation in winter and, deer debarks non-palatablespecies to attain fodder for its survival.

KenRyuichi

KANNO

MAJIMATaisuke

YukiraSATO

MOCHIDA

Stratigraphy and depositional
environment of the lower partof the Ikego Formation(Pliocene) of the Miura Group,
exposed at the northern Miura
Peninsula, Pacific side ofcentral Japan

I studied chaotic beds intercalated in the formation boundary between the Zushi Formationand the Ikego Formation. These beds are divided into the following four units: lower chaotic
unit (unit 1), sandstone and conglomerate dominated unit (unit 2), cross-bedded sandstone andconglomerate dominated unit (unit 3), and upper chaotic unit (unit 4), in ascending order.
They are interpreted respectively to be submarine slump bodies consisting of the uppermost
horizons of the Zushi Formation that are not exposed in the present exposures (unit 1), a fill ofslump scar (unit 2), dunes that have progradated from southwest judging from the crossbeddings (unit 3) and a submarine slump mass (unit 4).

In recent years to understand the ecology of the mangrove is believed to lead to theconservation of biological diversity.Therefore, in this study is to elucidate the ecology,
Three mangrove species offocusing on the herbivory of the leaves by comparing the herbivory rate at the species, thedifferences of herbivory due topurpose of the this study to reveal the factors that affect the herbivory. Herbivory rate is
the difference in the the trait ofdifferent among the three species, habitat, such as flood frequency had a significant impact.
the leaves and the habitat
Also, the trait of the leaves are affected under the same habitat, both factors of the traits ofleave and habitat has been suggested to affect the herbivory.

Hirokazu
Takahashi

Masahiro
IshikawaKeisuke

MasahiroTADA

ISHIKAWA

Simultaneous high PressureTemperature measurements ofP-wave and S-wave velocities
in Oki-Dogo xenoliths

Paleostresses inferred frommesoscale faults in thePleistocene Ashigara Group,
central Honshu, Japan

P-wave velocity (Vp), S-wave velocity (Vs) and Vp/Vs have been measured in the laboratory
for pyroxenitic xenoliths from Oki-Dogo, southwest Japan. Pyroxenitic xenoliths compriseolivine-poor websterite, and olivine websterite. Simultaneous measurements of Vp, Vs andVp/Vs were carried out at pressures up to 1.0 GPa and temperatures up to 600°C. Vp ofwebsterite rocks vary from 7.2–7.4km/s at 1.0 GPa which corresponds to representative depthfor Moho in Japan arc. Sub-Moho Vp beneath island arcs are intermediate (7.3–7.7 km/s) inplaces, and this study suggests that the intermediate Vp can be explained by pyroxenites.

The Ashigara Group is located in the northern part of the Izu collision zone and has been
provided a lot of significant information to understand the process of arc-arc collision. Inorder to estimate the principal stress axes and the stress ratio during the collision, we applied
Hough-transform-based inversion method to fault-slip datasets obtained from the Ashigara
Group and the Hontanikawa Formation. The four datasets from the Asigara Group yieldedconcordant stress axes with the known paleostresses, suggesting NW-SE and NE-SW trending
σ1 axes, but the observed area was different from the known mesoscale faults analysis. Theseresults also showed the stress ratio.

Kazuyasu

Ryuichi

TANABE

MAJIMA

Tatsuya

Ryuichi

MORIYAMA

MAJIMA

Takafumi

ShinjiYAMAGUCHISHIMODE

Paleocurrent analysis of theZushi Formation (upperMiocene - lower Pliocene) ofthe Miura Group, exposed at
the northern Miura Peninsula,
Kanagawa Prefectura, central
JapanThe upper Miocene to upper Pliocene Miura Group, a forearc basin-fill exposed at thenorthern Miura Peninsula, is composed of lower Zushi and upper Ikego Formations. I
measured paleocurrents of the sandstone beds of the Zushi Formation, using the fore sets ofcross-laminations and imbricate structures in the parallel laminations. These sandstones areinterpreted to have been deposited by northwestward- and eastward-directed sediment gravity
flows. The flow trends of the Zushi Formation are well concordant with those measured
previously in the upper Pliocene to lower Pleistocene Kazusa Group, overlain conformably
with the Miura Group.

Paleomagnetic analysis of thelower boundary of the Olduvai
subchronozone in a core
recovered from the NojimaFormation of the Kazusa
Group, the northern Miura
Peninsula

I measured paleomagnetic inclinations of the lower boundary of the Olduvai subchronozone
in the Lower Pleistocene Nojima Formation of the Kazusa Group, a fore arc basin fill, using acore (the core O) recovered from Yokohama City. The lower boundary of the Olduvai
subchronozone was identified between 64.93 m and 66.59 m in the core O based on
paleomagnetic inclination data. During this interval, three sign inversions of inclination, fromnegative to positive, from positive to negative, and from negative to positive, in ascendingorder, are observed. The lower two sign inversions, however, may reflect an influence of
diagenesis because concretions occur in the horizons.

Life history strategies and egg
production of planktonic
copepod Calanus sinicus inSagami Bay, JapanThe purpose of this study was to reveal life histories and to establish a model for predicting
egg production rate (EPR) of C. sinicus. Our result suggested that deep diapausing population
might return to the surface layer during winter to early spring. We proposed a multiple
regression model for estimating EPR using prosome lengths and gonad development stages ofadult females.