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,**2  , 8 +2 9 ,**2  ++ 8 +. 9Radiocarbon Ages of the Eruptive Products from the Eruptive Episodes E and G,Towada Volcano, Northeast Japan
Takashi KUDO῍
Towada volcano is an active volcano located at the northern part of the Northeast Japan arc. I carried out
AMS radiocarbon dating of two soil samples taken from directly below the tephra layers derived from the eruptiveepisodes E and G at Towada volcano. The obtained +.C ages were 2++*-* BP (PLD-23+-) for the eruptiveepisode E (Nambu Pumice) and 331*-/ BP (PLD-23+.) for the eruptive episode G (Shingo Pumice). On thebasis of the calibrated +.C ages and the stratigraphic relations, the most suitable ages of eruptive episodes E, F, G
and Ninokura Scoria were estimated to be approximately 3.,, +*.,, ++ and ++.1ῌ+/./ cal kyr BP, respectively.
These results enabled more detailed and reliable chronology of eruptive history during the post-caldera stage ofTowada volcano.
Key words : Towada volcano, eruptive episode E, eruptive episode G, AMS +.C dating, eruptive history+ῌ ῐ ῎ ῑ ῏:;.<:;.BCDE>FG H ++ km."/ (+300) 0123 (+303)

IJ@A;.KLA M + :;.I=>?@A +.C 45 (+31*)

67 (+31.) 4 (+310) / (+32-) Hayakawa

 

// ka (//ῌ(+32/) NEDO (+320) N23 (,**-) >OPQ R+/ ka) <+/ kaST I - IUVWX>YZQ[\ G3G ]Z^I W_` I;aYZQbA (Hayakawa, +32/) :;.I;cdefWg>h^Z\iIKLj <lmn Hayakawa (+32/) >Oj ;op Jq@

;rJ!@A>":KLP\ s]KN t#JEuGQ + vI ;defWg $>wYZ

x% (,**1)  sZyK +.C z& RI=J{F3^ A B C u| }~lnJ'bQ()YZ

> *,+ (AMS) ,>OA +. C -.

QbA :;./I;.u0GQ;I1Jb ;defWg>bQsI2Ki3456biII <kIK7

8u9:YZAJ;qG\ G3G ;defWIK <1= ;Jj > GQj Hayakawa,g E u F >bQ <A?z@AuYZ +32/ ; Nx% ,**1 ;.IJB@\ +.C ICzDyZQb\[A;.I + KLAu A ¡EI;JFy\ :;.<>¢AA;I-@A\£> ¤¥I;GHJK[A¦¢§¨>I+ uGQ ;defWg G z©ª^ZA ]I;

«GQ @AzLA sIKi;>?@A- JIKU¬­|>LYZA< ;I1 45¯° JMA\£IA±N
W_uA G\zPQ ²Phj4³5K¨´ W_ICu38;I;qzDyZA -*/ῌ2/01 !" +ῌ+ῌ+ # 1$%&'()*+,- )*AIST, Institute of Geology and Geoinformation,
Geological Survey of Japan, Central 1, Higashi® I:O=>U¬­|;zO UVWX3^ sI<I7
{Iµ¶J·¸KQ1=>¹º;z»]AU

VWX¼I¤R >1 GQbA y\ ]I;JE+ῌ+ῌ+, Tsukuba, Ibaraki -*/ῌ2/01Corresponding author : Takashi Kudo
e-mail : kudo-taka@aist.go.jp

7194

8Fig. +. Topographic map of Towada volcano showing the sampling site for +.C dating. A part of + : ,/,***
topographic map “Heraidake” published by the Geographical Survey Institute is used.
 ++. C /0 %1 9:;:<=>?'@ABC!"#$%&' ()*+ ,  / , +  -.

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mnop%qr'@hLCst>u@ v3 ]^_`a C w xy 2z{3 +32-53 3 ]^_`a G o`|U74}6

]^_`a D῍~\ (Hayakawa, +32/)3 ]^(,**1) > DS +.C  + $Lu3 v_`a D ~\ 27 4}63 ,**153 ]^<%&'@S9Uo`|%_`a E xy (Hayakawa, +32/)3 ]^_`'

>uTS

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(Hayakawa, +32/) >FS  9S)[F%93 ]^_`a E, F, G, !UxyWvxyW\ "#%3 %+TS 2 ,5 !"# 9U3 hXYZ>)S

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/( %+TS  U¬­®¯°±4Z²9³)S !U¹FCº»BG¼ῌp¢ῌ¼½

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qWO- +.C 2/

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cdxo$  ypK

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IntCal*. (Reimer et al., ,**.) yp|}~A CALIB/.*.+ (Stuiver and Reimer, +33-) _- ^ * yp$ +.C 2/ BPῌkyr BP yp
2K2/ cal BPῌcal kyr BP NwM-    -ῌ+ E  E $ $u0 2++*
-* BP (PLD-23+-) $2/01-  + 1J*  E KLM2/NOP   
$Z  u0  01- 20**  ,/* BP GaK-,0+- :FGHI +31* 2-1*+1* BP (GaK-+*0/* : Hayakawa,+32/) ,- ^ 10 _1m=.

*cd1-$* lm p ^1
P_^_ 01-2/  $2//**-** j_xoN^,--ῌ, G$u0 331*

 G $

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2/ $2/ 0**  _xoN^, 2/N¡¢L£$¤¥^ ¦ !§01^_. Q

 (,**1)

 RST8¨4©As$ª Kk_P «¬4KM­$®
#*¯°"N#±1M2²O- * 
01-2/_P   E, F, G 
V$$³«C´3$2µ¶%M.ῌ+ Fig. ,. Geological columnar section at the samplingsite. Numerals in rectangles are +.C date. Alphabets represent the name of eruptive episodes.
Words in parentheses represent the name oferuptive units.
 ,  !"#$"%&' ()*+,-.
/ 01- +.C 2/ 34567    

Q (,**1)E E $2NO

P Hayakawa (+32/) KM 2-1*+1* BP $2/O- ­OP $$ d +-C /Z$·¸/*M,/(Stuiver and Polach, +311) N¹dOPyp]^_   E $2­3.. cal kyr BP NO- OuO $2/ º»&y¼F½ lm p^1P_^_-§ !

196
Table +.

"

Results of AMS+.C dating.

 + AMS +.C #$%& &' +.C ()*+,-./012 -3 !

-4 56 AMS 73789:-;

<A



B-#-- C78D /**-** E3

 (,**1) 78=>>?@ ! < (,**1) @ FGH)I E J7K G

L:@ B#MNO@POQ& W#X@Y$Z @[%&\Z]^D8 JJ7W +* cal kyr BP  56 E  G_` - Wab@'OZ  L-c(L78 c& F ]^d@ eDfghi)j@*+&RSTU!,V" F D8, E 73 op-O@! <  (,**1) -.

F J7K G klRST-mn/ qr/0OfV()*s]^D 561t 2F @ +*.+

-34OZ _`  56 BP 3 L@! <  (,**1) ]^8u@JJ7W 3.* cal kyr BP  + OZ8 5l1t

v@JJ7W 3., cal kyr BP  <!

 (,**1) @>?,x!,s2++*

3

.ῌ-  G.ῌ,  F!

+*.. cal kyr BP 1t@2 +*., cal kyr< (,**1) @FGH)I G FGH)I F =>

 3--* -/ BP (PLD-0-11) w# 6s JJ-* BP (PLD-0-13) 

7W +*.0 cal kyr BP  y&567z  s! <  (,**1) @ {x@ 331*

RSTRSTU!,V~ L

3 5l h@ yOZ - F @E2 "& :- #X@Y$Z _` -s3 L@ 56  {B89 Wab@'OZ  op-O@ 5l1t

-/ BP  C  78D 0**  u|}

 FGH)I E ,xy:J8 F 2 -34OZ _`  56@E2!

< (,**1) 2  -3 ! <  (,**1) 7 =@JJ7W ++.. cal kyr BP  + OZ

8 5l1t@JJ7W ++ cal kyr BP  >>?@ E;./Ds.ῌ.

01-Z   q)@ =>

<@=xf x>?

>?f>~-? {BfOZ8 L@^@A (T¡!,-W¢BC&D£¤¥ ]¦N{ f§ FGH)I L ,s¨48

E!,-©ª2 «¬OZ  W­ ®¯}!

G  Hayakawa, +32/ ;   ,**-,f@E;O./ °±1-Z  /0mn! <  (,**1) @c&²3L³ !

78< (,**1) -Y$FGH)IFGH)I L J7K G < ´pµJJ7W +/ῌ+++/0O@ fV / cm =>>?-¶rE

cal kyr BP · 56

F¸!,GQH`3 ¹r-+& L-c(D ' Horiuchi et al. (,**1) FGH)I G L@ {º7»¼½O=>>?,x!

78FGH)I L  AMS +.C -7zL  :;<=> E ? G @ABCD

197%4 &'()*EF#6GHI"JKL1 Horiuchi et al. (,**1) .  :;<=> L M NOPQRQS ,+.

EF#6

C T"JK# U5V5WX /4  "+/./ cal kyr BP %01 7

. !Y Z[\ NEG51QS4"451G\]^  "_06#$%#$`5$ 7
"a b$% &'()*@+cd.
U +/./ cal kyr BP %K$ e% &'()*%
G fghi,E. ,ῌ+. cm &jklmnb$  ,**1 E-G ,&jOP! EF#6. opq'`51 % / rs()kt=u4 U *.*, cmῌ%vPG45$ 7OP! " #$% &'()*% G +,,-. +**ῌ
1** ,%w@`5$ &jklxyE^*z06#$r='"2+06W{+,,-"a 0  :;<=> G " ++ cal kyr BP %b$% &'()*@+|d.U ++.1 cal kyr BP %K$ }|^  &'()*  @+.U +/./ῌ
++.1 cal kyr BP %K$/  ,\q'01 " #601  " - E_b ~1 E:;<=>E$  ,-` E
 "%L1" . E_b }c\.
 .EF#6$%%GE


E%GK // 0zEF#6,b$ K 12K,.

(,**1) \GJKL1l 77\.q'`51ER ^0,b$
\. +/./ cal kyr BP E7L1 :;<=> L E^ nv45$  l`51 (Hayakawa, +32/)

 3.U4 4`51 (Hayakawa, +32/) 3. E5  E$$¡6K'()*

Fig. -. Chronology of eruptive history during thepost-caldera stage of Towada volcano. Ages :*, Machida et al. (+32+) and Hayakawa andKoyama (+332) ; **, Kudo and Sasaki (,**1) ;***, Kudo et al. (,**-) ; ****, this paper ; *****,
Horiuchi et al. (,**1).
 -    : *   (+32+) 
(+332) ; **   (,**1) ; ***  (,**-) ; ****
 ; ***** Horiuchi etal. (,**1).

¢@ &'()*  £K$7

    @E$k\ 89 45$

Hayakawa, +32/ ; Hunter and Blake, +33/ ; 89\/06#1%2345$  .

,**- ,**. 7e:3. U ++.1 cal kyr BP

&'()*@}¤.  ¥l¦§¦~\-2** ,¡#1%2345$  - 7+E. ªK%G ++ pN¨©E0zb$%%GE Hunter and Blake, +33/ ; 8l«;+,,¬\

9 +333 ; 8­® ,**1  2¯l^</01%23456#$7%4 89 ,**-6EK^ °)±=¯ % ²³´ lµ¶U -/* ,¬\b$EKL1 (Hayakawa, +32/) ~¸ ++ cal kyr BPl/06#1%·`5$ ¹ºE.U5}|/ \ l/06#1%=E G »`56^    ,**1 +/./ῌ++.1 cal kyr

kyr BP E E, 2., cal kyr BP E D, 1./ cal kyr BP E D῍ 0.+BP E. -/* }c>¼6?#+,,¬\cal kyr BP E C  l7L1 7+. 1**ῌ+.**l½/l7L1

 +*., cal kyr BP E F, 3., cal)198

0 

 *+,'- E ./ G012345 AMS C 678+.

"  *+,'- E9 :; 2++* -* BP, *+,'- G <9 :; 331* -/ BP =:!" >?:!"6@  *+,'- E F G (ABC6DEF G678" HIJ KLMN !
O "#!P

 ; H!Q!RH E : 3.,

cal kyr BP, F : +*., cal kyr BP, G : ++ cal kyr BP, (ABC : ++.1ῌ+/./ cal kyr BP O8" >?
Fig. .. Temporal variations of repose time beforeeruption during the post-caldera stage of Towada
volcano.
 .
  

IJRS  RS$T
U%=V&OS'() '*+,

WX=RS-Y8" > Z!:'[6@  '*+,  \. ]^]/0_O`a345bc61d   e2f(0gOH_ 3h6i-F54j"4

4,_kL ='*F5S (ABCO5lmO _k;-:6F  +,;n7F54  - R/ .
C  op61dq"S rstuvwx

; 8 -.** _y"5l96

6L ,.1 cal kyr BP  B ='*F H

 8 +1** _6LDE 3+/  A =Z8"  -C O5lmO _k;:6F +,;n7F54R.
QR9WX6O ){: (,**1) =SF"R OON _k=6F  '*+,=]2mWX=^d:!  .

7ON_: C 5; OON
_k=`6F54  .

C N _k;6F54N C-B _=f¤9
64"d H!Rij L;854  .

Z!; C © e2f(0gª: =q8"ZO6«¬m C  L;­8 km W ¡®¯'[' q4; =°0 !

"On !54 (Hayakawa, +32/) Z!=o]^]±²³´µ6p e2f(0g ¶6N":F"V&q=q FF >OZ·H3h6rm
;¸8544 > P *+,'-st6DEF"ML  '*+,  \. ]^]/
0_ `a345bc674   e2f(0gOH_ 3h345i-F54j"4Ob54z{ :|;};<=~:>4"454 % .?;} @o  ABCF GH R/IJA; K>6GLmMLNA64"4" ZZF5O
PFMm  T?U V (+32-)  WX01YZ[ \,/0  ,2 ,0-ῌ,1-.
Hayakawa, Y. (+32/) Pyroclastic geology of Towada volcano. Bull. Earthq. Res. Inst. 0*, /*1ῌ/3,.
T?U Vabc (+332) =K¡6; L +* de¢4LZ8"3H £=#Ogh .- .*-ῌ.*1.
k¢l¥?¦§ (+300) +*** f(¨m' !"#$%&'( no. +.* +*ῌ
,2.
Horiuchi, K., Sonoda, S., Matsuzaki, H. and Ohyama, M.
(,**1) Radiocarbon analysis of tree rings from a +/./-cal
kyr BP pyroclastically buried forest : a pilot study. Radiocarbon, .3, ++,-ῌ++-,.
Hunter, A.G. and Blake, S. (+33/) Petrogenetic evolutionof a transitional tholeiitic  calc-alkaline series : Towada
volcano, Japan. Jour. Petrol., -0, +/13ῌ0*/.
){:| (,**1)  su¹v, U%
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)
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M½ 0*** _ e2U$º +*3+/+ῌ+0/.  E  G    (+333)  !"#$%
2 345 6789:; /* 033ῌ1+*.
   (,**-) )CDEFGH?IJ KLM)CDEFG$ NO
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45   (,**.) )C$PQ .3 -01ῌ-2+.
PRSTD
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Reimer, P. J., Baillie, M.G.L., Bard, E., Bayliss, A., Beck,J.W., Bertrand, C. J.H., Blackwell, P.G., Buck, C.E.,
Burr, G.S., Cutler, K.B., Damon, P.E., Edwards, R.L.,
Fairbanks, R.G., Friedrich, M., Guilderson, T.P., Hogg,A.G., Hughen, K.A., Kromer, B., McCormac, F.G.,
Manning, S.W., Ramsey, C.B., Reimer, R.W., Remmele,S., Southon, J.R., Stuiver, M., Talamo, S., Taylor, F.W.,
van der Plicht, J. and Weyhenmeyer, C.E. (,**.) IntCal*. terrestrial radiocarbon age calibration, ,0ῌ* ka BP.
Radiocarbon, .0, +*,3ῌ+*/2.
Stuiver, M. and Polach, H.A. (+311) Discussion : reportingof +.C data. Radiocarbon, +3, -//ῌ-0-.
Stuiver, M. and Reimer, P. J. (+33-) Extended +.C database and revised CALIB -.* +.C age calibration program.
Radiocarbon, -/, ,+/ῌ,-*.
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