-

130˚ 140˚

20˚

30˚

40˚

50˚170˚

)9371 DA( a-aT)4961 DA( 2c-oK

1968M 7.9

1952M 8.2

2003M 8.0

1973M 7.4

1894M 7.9

1856M 7.5

1843M 8.0

100 km

N

145˚ 43˚

a b

c 3

N

146˚

43˚30'

cbHokkaido

B-Tm(AD 937-938)

N

)C ht01 .ac( b-aM

30 km

fo ytilibaborP

6.8 M

8 cm/year

a

B-2

(m)

5

0

-5

-10

B-2B-1

B'B

200 m

C C'C-4

C-1 C-2 C-6

C-8

C-7

C-5

5

0

-5

-10

-15

-20

(m)

-25

-30200 m

C-3

C''

C-9C-10

C-11 C-12C-13

C-14

B

''

A

A'A''

A'''

2000 m

N

C??

BC C

A

C-1 C-2 C-3 C-4C-5C-6C-7C-8C-9C-10 C-11 C-12 C-13 C-14

A-1 A-2 A-3 A-4A-5A-6

A-7 A-8

A-9 A-10A-11A-12A-13

A-17 A-16 A-15 A-14B-1B-2B-3N

2000 m

144

50

00

43 02 00

Inner Bay Facies

Lagoonal Facies

Barria Facies?

Barria Facies?

Lacustrine Facies

Marsh Facies

Tidal Flat Facies

A-14A-11

A-13A-10

A-8A-7

100(m)

Ma-f(7.5 ka)

A-15

A-16 A-17

A-6A-5A-4A-3

A-1 A-2

A-9 A-12

5

0

-5

-10

-15

-20

-25

-30

-35

-40

-45

-50

-55

-60

-65

-70

-75

(m)A

WNW ESE NNEA'' A'''A'

N

a

b

Developmental processes of Holocene barrier system based on borehole data around Akashi bay area, eastern Hokkaido, Japan

Key wardsL

ac

ustr

ine

Fa

cie

sT

i da

lF

lat

Fa

cie

sI n

ne

rB

ay

Fa

cie

sBa

rria

Faci

es

Age (cal yrs BP)

)m(edutitl

A

Ta-d (ca. 9.1 ka)

TS at ca. 11.4 ka

sea-levelcurve

depositional curve

-10

-15

0

5

-5

-20

-25

-30

-35

-40

-45

-50

-55

-60

H-20-1-(6) (-27.30m)

H-20-D (-49.7m)

uppershoreface

lowershoreface

sandytidal flat

muddytidal flat

HWL=1.50m

LWL=-0.10m

innershelf

lacustrine

PebblesClay

Silt

SandShellsBurrows Wood Plant

LaminatiomsMud clasts

H-20-E (-60.8m)

12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0

SB at ca. 13.8 ka

H-20-(3) (-13.30m) H-20-1

(-9.85m)

H-20-2 (-23.87m)

H-20-3 (-43.85m)

H-20-A (-13.65m)

H-20-C (-30.90m)

H-20-(1) (-6.23m)

H-20-(2) (-8.30m)

H-20-(4) (-17.30m)

H-20-(5) (-22.30m)

H-20-1-(7) (-39.30m)

H-20-1-(8) (-39.30m)

H-21-5 (-6.76m)

H-21-2 (-46.86m)

tidal channel

Altitude (m)

0

-10

-20

-30

-40

-50

-60

yalc

sfv

tlis sf

sm sc

scv

SB

TS

Ta-d (ca. 9.1 ka)

viscosity model C (Maeda et al.,1992)

Chiraikaribetsu (Sawai and Misio, 1998)

Hichirippu (Sawai, 2007)Kiritappu(Sawai et al.,2009; Maeda et al.,2009

Akkeshi (Sugimura,1984)plantpeatshellscale

new AMS data

Mochirippu (Sawai et al., 2009)

Bekanbeushi (Matsushima.,2006

Chlamys farreri Callithaca adamsReticunassa

multigranosa Callithaca adamsi Ruditapes philippinarum

Batillaria cumingii Ruditapes philippinarum