?@A

88

ῌ

῍

 




+

 * 
+

+

,



+





 !", #$ %, &'()*,+,- +3 . / / ,+ 012 ,- +3 . 1 / 3 0134

Geochemical character and origin of hot springs andfumaroles in Doroyu and Kawarage areas,
Akita Prefecture
Osamu MATSUBAYA+*, Hiroshi KAWARAYA+, Daizo ISHIYAMA+,
Yoshinobu TAKAHASHI,, Masaru SUZUKI, and Kazuo IGARASHI,+

Faculty of Engineering and Resource Science, Akita University,
Akita Geothermal Energy, CO., LTD.

Abstract
Doroyu hot spring area and Kawarage-jigoku geothermal area are located at a distance of about +km to each other, and also both are adjacent to the Uenotai geothermal
power plant. In order to inspect interference of the geothermal power plant operation tothese natural geothermal activities, geochemical character and origin of geothermal
water in these two areas are examined on the basis of hydrogen and oxygen isotopic
ratios as well as chemical composition of hot spring water and fumarolic steam, whichhave been observed since +32/, intermittently. In the Kawarage area, strong acid Cl-SO.
type hot springs show a relationship of hydrogen and oxygen isotopic ratios (dD vs. d+2O)
that is characteristic of mixing of island arc volcanic steam and local meteoric water.
Also dD and d+2O of fumarolic steam show a relationship of steam boiling away from thestrong acid Cl-SO. type hot spring water at about +/*5, in the underground. These
characteristic features have been constantly kept through the observation period, and no
signiﬁcant change is observed between before and after the start of the geothermal power
plant operation in +33.. In the Doroyu area, boiling hot spring water and fumarolic steam
show a linear relationship of dD and d+2O caused by steam-hot water separation in boilingat about ++*5, near the surface. The isotopic ratios of original geothermal water before
the boiling is di$cult to estimate, because the amount ratio of steam and hot water is notexactly determined. This linear relationship, however, ﬁts the average relationship oflocal meteoric water, suggesting a meteoric water origin of the original geothermal water* ,**/ . - /67 89:;<=>

» /1 ¼ ,**1  A01 º67,W59t

89

before the boiling. On the contrary, the geothermal water used in the Uenotai geothermal
power plant has a dD vs. d+2O relationship clearly di#erent from the original geothermal
water in the Doroyu area, or the average relationship of local meteoric water, though thegeothermal water used in the Uenotai geothermal power plant is also of meteoric waterorigin. The observation results mentioned above reveal clearly that three kinds of geothermal activities di#erent in their origins exist within + or , km distance. This fact suggests rationally that these geothermal waters come up through isolated individual paths
at depth shallower, at least, than the depth of bore holes in the Uenotai geothermal power
plant, about , km, and no interaction happens during ascending of these geothermal
waters.
Key words : Doroyu hot spring, Kawarage-jigoku, Uenotai geothermal power plant, Hydrogen isotopic ratio, Oxygen isotopic ratio, Origin of geothermal waterῒῑ
 + km    !"# $ %&'()* *+ !* ,- +32/ . /01/2 32456789+:;,<=>
?@  A-  /2 324BC*! D3E Cl-SO. F/ G
HIJK5"/LM>N-OP Q>1 *! +/*R ->/S1O5TUV> W XYZ[\]^_!` ab'cdV> +33.
ef-6 g!h   A10  dD 5 d+2O ' ij
++*R -/S15/BC+k '  l"/mn+o 5*!"/pq5TUV 5 r'  /  "/pq-O'  dD 5
d+2O BC  AN5 !*sh . 5*! 9tsh - u /' vhj5N wx'yz  , km .{-  
>o+|}j5~'-OP Q>|-  () h    :  pq   /24 324/+ῌ ῏ ῍ ῐ ῎
 !"#  5
P  

 5'%+&* *  '( }> +30*

 + km ]O

 } *!$ /+V'(,V

*!)5V VQQh*' P+V}¡> ,¢ - +33. £h+)5¤M ¥.h 5 + ¦  -§/ /5%/
E¨+ !* 9t V! *! Q-©ªV«+TU 0¬B1+2­ 5-O ,¢ 3!45 l- ® 5¯ '°I
HI0±*! -²/ km >5 r £hiON**_!`
0

/

 *Nwx'y}   , km PN{ 5 r- "/pq-OP 5

r'°IHI0±h , u/'³´µj>o+o¶}/5'

HIJKpq-O
!pqs!*V}



·6¸ +330 +331 ; 78ῌ·6¸ ,**,

 - (*9-   A A/015 -§/V /B1+ !* ,- +32/*!:;,¹¶}¡>/01/2 32

<=°

90



    

!"#$%&'  ()* +32/ +,- ./012 34 5+3136  Takano and Watanuki 5+31.6#78*9&',   

,+ 

:;<=>:;? @A*B9& 5C +6' D EF*> G ; 5HIJK6 0LMN ;0OPQ& , R STUV=WX&' Q Y*E*>ZN[\]^W_`1 a< ()bc\>de1 fg hijk0lbk#m n09&\Wop*qV12N&'
D rFs> I tuvWw +** m x syz1 y{|W9}g#~12N&' yzD>b#2g  *[\]^WN2N(0YQ&' yzD EF
s>y{|[\WV2g 9}g*YQ(b[V9&c\WJK <=012YQ2('  ,-> rFs>[\]^>Qp >
soQ2N(' 0~W ,*** +gZN[\WQ&*g ,**. +*>[\W ¡*] *g¢`£sN2N&' £( EF [\>,-¤¥*Z£¦22N(WrF [\W] *¦(§>Y*Z£¦(',, 

G¨©ª>:;<= X&:;? t«g ;¬? ­®q4*Xg :;<=0>¯ + km

Fig. +

Localities of Doroyu hot spring and Kawarage areas and Uenotai geothermal power plant.
 +   

R /1 ¼ E,**1F

2 3 O ]&CU-.¥ !»(PQ5HI 91 

  !"# $ %&'( )*+ Cl-SO. ,-." /0 .12 3 4&-. 560 4&-.  -.7 85
9:*; <=*>?@A"B/0" &C)*+.D*; <=*>?@A"B/ ETakano and Watanuki, +31.F GHI"J5"KLM
N)*+-.O PQR E,**0F ST",- 

UVWXYZ[\] +31+  ^ _!`ab
cd U""#5$%M +32* ]& ef '(5ghWi
j"VkM +322 &)*lm+l,7n!"-5"o.M +33. &"VkM pq / + km, !`$ +r, km s01t ,0* uv7"wM ,2,2** kW &"ab 7 +* xyiwM" z{2xyi7 3bl7n!|"- }2xyiD7n!
~4D"- 557n!~" 2/῍  7H
+ Na-Cl ,  Cl 60 +**r-** mgῌl   60757n!"
0D7n! +}7OD $ -5
7~" 60]D760 $wM7 &8M,"$9M &
E+321F ῌ

efWcd

E+33,F :M 

--+ 

%&'( /0)*+ Cl-SO. ,-.O;G+32/  <=ῌ

E+33*F >DD<-.77 *5?]OH

@ %(a
M

 

O ¡ E+313F ] +310 @cd"

D5 Takano and Watanuki E+31.F ]H":M 

@cd> + K05  !O +321  , 

 ,**+  +  7n!7 *5? @ E> ,F  ! !g-0" +**¢ £D 7n!AB*C57 <=" ¤7¥B* < l D: ¦E No. + 5 No. -  B*C +..r+.0῍ < " ¤7
60 *.**+῍$

§ ,  &CU-.75 !7n!75? EdD, SMOWF 5*5? Ed+2O,
SMOWF J¨ ©7 E'&7 $7F J¨ E<=ῌ

+33*F 5bªK

D )*+ Cl-SO. ,-.7 dD 5 d+2O J¨ dD 5 d+2O F"7G]
D  4&-. J¨560 4&-. HIHῌ<= E,**,F ]«¬IM J­®®¯°57"D5$%M ]zlJ­®K®¯°7n! dD±²+/r².*³ d+2O±´0r´2³ µ"l5? " ED: Giggenbach, +33, ; <= +330F ®¯°57x¶7 dD 5
d+2O J¨J­®¯°J¨57J¨ c·L¸M·

!AB*C B* ®¯°N7n7 ¤7 <| "¹º75

!"#

92
Table + Hydrogen and oxygen isotopic ratios and chemical composition of strong acid
Cl-SO. type hot spring water in the Kawarage area.
 +

Cl-SO.



NO.

*.



pH

Cl, mg/lSO., mg/l

+*+
,*+
-*+
.*+
/*,
0*1*2*3
+*
++
+,
++.
+/
+0
+1
+2
+3
,*
,+
,,
,,.
,/
,0
,1

+303. 3 . ,/

+31*. +*. /+310. +*. .
+32/. +*. -++321. 1 . +1

+321. +*. +.
+331. 0 . ,/,***. 0 . +0,***. 2 . ,,***. ++. 0,**+. 3 . ,+,**,. 2 . ,3,**-. 2 . ,2,**.. 2 . ,/,**/. 2 . ++,**0. 2 . ,,

32
3.
3.
30
23
32
21
21

+40
+40
+40
+40
+4.
+4.
+4,
+4,

+.23
+/33
+/2/
+020
+.++

21
31
31

+4,

+203
+3,+
+33*
,*11
,*+,
,+**
,+**
,+**
,+**
,+**
+2**

31
31
30

+4.
+4.
+4-

,-**
,,**
,-**

+4+4,

,+.*
,-+*

dD, 

d +2O, 

/.4/
/0
/2
/1
/0
/0
/2
/1
//
/0
/0
//
/0
/.
///.
//
//
/0
//
/.
/-

14*14,
141
14/
1414.
140
14.
14*
043
141
14,
043
14*
1414,
14,
043
14,
14.
14*
14,
043

+*3*
+++*

*+ : Takano and Watanuki +31.
*, :
 +313*- :   +33**. : 

Table , Hydrogen and oxygen isotopic ratios offumarolic steam in the Kawarage area.
 ,
!"#$

NO.





dD, 

d+2O, +,-+321. +*. +.
,**+. +*. ,3

+*+
31

01
0/
02

+*40
+*40
+*42

» /1 ¼ ,**1

°±² ³´!Z^µ¶$%U·¸¹ PRº  

93 

   Cl-SO.   ,

!"# Cl-SO. $%&'(&')*+,-)./01"2
d+2O 708

3456

9:;

dD <,/8 = " d O 728  9+2:; dD <,+8

>?@ABCDEF6  GH# 9 Cl-SO. $%>?@ABC(IJGK LMN  OG P
IJQJ" @ABCR ,*῍;= +2Fig. , dD vs. d O plot of strong acid Cl-SO. type hotspring and fumarolic steam in the Kawarage area fora period from +310 to ,**0, and of meteoric water inthe vicinity.
, Cl-SO.  +310
 ,**0  !"# $%&'( !" dD  d+2O )*

(STUV"# WX
Y" P ./0 Cl-SO. $%ZK [# dD  +,8 d+2O  -./8 \" 9&']^$%!_ ` a U&' bῌc d ,**,
dD  +,8

d+2O  -./8

2e. ;= "3f

gU U h; +/*i ;

+33.

2ejk6  OG @ABC (IJ; Gl gU6mn./0 +.8 -./8 Horita and Wesolowski,
o `gUpq6 

9Nr9 sr 9(STU ]^$% . tu@ABC (IJ; Gv; +/*i /$w;l GgU LMN  +/*i gUx ..1 Ux;= 9Nyx; /* m z6  GH# 9l{|;}9H#"

~XMN -, 

 Cl-SO. $%

./0 + 6Z3W)G +32/

srO;2ejX;= OGr +313 MNG +310
X*D;=  OG; +310WXK +32/

Cl wV"#K|.;=r +313 !Z +303

+31*

+32/

W

2ejX

Takano and Watanuki, +31. KP

D;=  (STU./0V"#K +321,**+

h;frN

"  ,
9Z3./0 RjX;="39  9Nr$%UR

6>?@ABC vIJ !ZPNZ Gv;l "3Y| K .*h= "Mr|srX #"G9 )6 ¡¢rN

 OG t£¤¥¦§)¨G +33.

©ª;9Nr./0Rf

«rN"9 sr ¤¥!"#vsr)¬­6 9 tuX®¯)¢#"" ~XMN 

QRop

94

.  .+     ,***  

)*+ ,-./0 -!"#$%

 +321

 ,**+  ,**. 

&'(1234+ ,-  56 7689:;<= No. 1  >(?@ A -12 +

BC<=(1+ ,BCA -1

DEF5GHI(J4! KLMN7O Cl-SO. PQR5GHIS T

Table - Hydrogen and oxygen isotopic ratios of steam and boiling water in
the northern part of Doroyu area.
 - 

NO.

U5V

WXYZ

Q[\

pH

dD, ]

d+2O, ]+*+,*,

+310. +*. .
+321. +*. ,2^,***. 2 . ,,**+. +*. ,3,**.. / . ,0^^ _`5
 abc5
 ab5d _`5

^
>

32

/4,
/4*

32

140

20
32
31

,4.
,4*
,4*

e3,4,
e//
e2+
e.0
e1.
e/2
e.1
e-1

e+14*/
e34+
e+.4e141e+,4e34/
e14,
e+40

.
/
0
1

*+ : fg h+313i*, : jkl mn h+33*i

Fig. - dD vs. d+2O of boiling water and steam in the northern part of Doroyu
area for a period from +310 to ,**.. The extent of geothermal water usedin the Uenotai geothermal power plant is also shown.
 - 
  +310  ! ,**. 
"# dD  d+2O $% &'()*+,-.#/0123+
4567 dD  d+2O 89

S /1 ¼ &,**1(

v3¶ 7 5·¸¹PjºHT »[eQR 8RS    -  dD

 ++* and Wesolowski, +33.( 

!"#
&/.+(

$%

d+2O  / 

)#

&,.'(

*+ ,"$%&..1'( &Horita

-. /  0,"1 23     ,"4 $%
89:

95

5"  67"$% ; <:;= >  <:;

"  ?@ABC /@ + $,"
H -.  "DE dD@  /A 

d+2O /BFG: .0  "IJK  .LM,"/ N"-. LM

OP.   A@= DEIQ,"/  /DERSP. 8# )# $% 
A@ Q@/  @A

-.DE@  /A T dD

d+2O U,/VWI"/ @A /DEIDE ," 
8# )# $% /V

X  "Y!Z;  /A")[## $[#I\] ^[#T")[$_I\ %`a /A
Clb &' , mgῌl (' &+321 )( ")[##&' +.,῍ " ^[#&' *.**+῍ c?" /5d[efRB*+,gh-7"DE

X," // @A  /,ijDE"/ Uk7"/l B*+,gh-7." dD

d+2O /V

m" B*+,gnop@A.A"qp/0,"r - 

G:   8As@ADE dD

d+2O 

 - U,1t" 67" &2ῌu3 +33, ; v3wxyz{&|( 4+ ( /DE dD /VW5/}+*' 56~A@ 7j B*j dD m"/  =Z; 8

 @A9,"IDE ,"8Y!

.  ?: ;  BC,"D/" ? G:F(m"@ 6
7"
/,ij< T$ ,*** )5=@A> +** m *F? /P. 81 dD

d+2O K=/ @A @ 0? , AB7" =)cB ? BC:C BC =- BC  /lI.>?   67" /,ijKVDI !." d/  ¡¢5d 0?£E¤-.¥F D/-./ IUk," >¦ ?§-9g¨T@©GªnH. /l ¡¢ ?§"1ªn¢I,"r «A=)cB ?J¬ .  ­`A"-. ¡¢5d ? +** ) d5dr@$£=' =¥F7.@ 67"   ,**. ) pH /  85d0?5 \"$[#)[7/ 5" 67"
No. 1 K; $% IU,/ +4? $%®5" ,¯ K/0 &L0( ," /0 +I:° W:-." 89: +
/0i.±M"  +4? $%® &%`a Matsubaya and Sakai,+312( 5 d O +4² $%+2

5 7A;="/ ?³,"B*+,g´µNOP. Q@ABI?, 

OP

96

  +321  ,***,**. 

  !"#$%&'(., 

-./0123

)*

+,


:;<=(> . ?@/ABA dD 

.456789

d+2O CD(E . ?@/AB+, F ( G6H ( -IJKLM Cl-SO. NOPQRQSTCD UV AW X.!@YA!Z[\ῌ[.?@"QQ]\456^_
CD UV BW 5`@+, HaH -.9ba + +310  +321  , c(-I

J Cl-SO. NOPRQSTCDdeTf@+, gh i , jk Cl lm( ,*** no0Aop , HaH i +310  +321 OPQ-IJ Cl-SO. N4q!"Qhtu+ FSTv4567a(w -*῍ B+ Cl lma(RQrs

2*῍ xy z A {|@+, 4567CDa( }H~ -.-IJ4  }!"QX.!@YA!Z!"Q"QAT p o UdD///1
d+2O3.*3./W STHhtu+ dD  d+2O CD ,*** n V B  i }!"QSv

hiy+, HaH FTo -. +310  +321  Cl lm-IJ Cl-SO. NOP +/,*῍ B+ -.S

Table . Hydrogen and oxygen isotopic ratios and chemical composition of Kawanoyu andMearainoyu in the Doroyu area.
.

 

 

Q

Om

pH

Cl, mg/lSO., mg/l

dD, d+2O, 

+*+
,*,
.
/
0
1
2

+310. +*. +321. +*. +.
,***. 2 . ,,***. ++. 0,***. +,. .
,***. +,. ,,,**+. 2 . -*,**0. 2 . ,,

211
11

/4/
/40
.4/

-*1
-1*
,1-

+..

-41

,0+

/24*
/3
/0
/0
/1
//
/1
//

24*.
24.
242
240
241
241
240
24.

23

.
+42
+42
,4*

-.*
,-*
3-

+41
+42

+,*
+0*

/2
0*
0+
/3
/2
0*
/3
/2
0*
0*

34/
34/
342
341
34/
34,
341
34+*4*
34/

NO.
-.

3
+*
++
+,
++.
+/
+0
+1
+2

+32/. +*. -++321. +*. +.
,***. 2 . ,,***. ++. 0,**+. 2 . -*,**,. 2 . ,0,**-. 2 . ,2,**.. 2 . ,/,**/. 2 . ++,**0. 2 . ,,*+ :  U+313W*, :   U+33*W

00,
0,

+-2*
++0*

» /1 ¼ ^,**1a´µ¶# !$%&'p ?mJ ·L¸¹º:u97

 Cl 




!"# dD  d+2O $%& Cl '!%()*'!* +, -./0123 4567
8)8 , -./0
123 09"# , :)# ;,B"<= >( ?@ACD8 $# '!EFD
4;GH09#  !IFD4;
*"#

>(

? ,**. !1

GJG K8 L M NOP4FL7
8*G%8 

!4)# Cl  +32/  +321 G>9QR4
Fig. . dD vs. d+2O of the Kawanoyu and Mearainoyu,
two natural hot springs in the southern part of
Doroyu area. The lines A and B are the mixing
line of Cl-SO. type hot spring in the Kawarage
area and the local meteoric water (Fig. ,), andthe line of steam-hot water separation in boilingin the Doroyu area (Fig. -), respectively.
 . 
  dD
 d+2O   A  ,  
Cl-SO.    !"#$  B
 - $%&'()' #$"S0TT9$(# '!GB9
@A

U VW0* X

0*%Y@A
N0*# <ZU [P\] ^+33.

_`a bcGB9"# de89fghij*"k0 l# '!m !no ^'pU(a GqeEJrstG@uv*"*wx*Gy

%YGz{8 *8Jrs4"# de" |J"}~8# FLM L
MJ G%YG9 :G" 09$(# *"rs%YGz{8 * ?G)'po1 G(_@A Cl-SO.
 N4:8# 0 |JJrs;(# :J 09# de":rs}GR9*4'!m !L*4/   
!$%&'p ?mJGB9  M# FM123&GL_N
*78 'pIFD Cl-SO.  ",  + H . ( 4¡0

4;(# ,¢(£ J": N4 +/*¤ 24# 0

|J4; ! ?o >( ?Jm!", @A4;(# : M# FM123
"* +, -./# ¥<Z[P, @AG¦ '!$%& !" >( ?1 , @A1 @A"

# 'p ?

¡ 0)CD§_<%YG# * +4" @A;"u¦ - ¨«¬G­e **# *8

 +©, km ª®¯°e±²²9#

G³

z

98

  , km     !" , km #$ %&'(")* +,-.'/
0102)345* )* 2/  , km6;)!< km6786'*#9   2): =)'9>?@AB CD@E FABG H*I) ABG JD22KLMH*I)NO PQ'RS'/ TOUVWT'/)2"X)* 78YZ[\6]^(@ F
!_` %&RSabc)*ῌ῏῎῍defg   heij kl Lm n+313o : pqrkῌῌpst6ῌuvwx6 Jyz{Z 6|ῌ}|!~{ZOU"# $ -* +11ῌ+31.
Horita, J. and Wesolowski, D. J. (+33.) : Liquid-vapor fractionation of oxygen and hydrogenisotopes of water from the freezing to the critical temperature, Geochim. Cosmochim.
Acta, /2, -.,/ῌ-.-1.
Giggenbach, W.F. (+33,) : Isotopic shifts in waters from geothermal and volcanic systems
along convergent plate boundaries and their origin, Earth Planet. Sci. Lett., ++-, .3/ῌ/+*.

%j n+330o : 66|ῌ}|!~&2)('(  +0 +/.ῌ+/2.
%j n+331o : pq!~{ZOUyz{Z) z .1 +*.ῌ++*.
Matsubaya, O. and Sakai, H. (+312) : D/H and +2O/+0O fractionation factors in evaporation ofwater at 0* and 2*. Geochem. Jour., +,, +,+ῌ+,0.

%j * n+33*o : rkῌῌpst66|}|!~& pz,z8z$ // +ῌ2.
+, %j n,**,o : pqV'OH6Z[Uyz- ./ yz -0 2+ῌ22.
¡ 0¢ £*12 ¤ ¥ 3¦  n+321o :T'OH§¨ ,. ++-ῌ+-/.

¡ 0¢ ©  n+33,o :ª§¨ 8  ., ,,-ῌ,.*.

45 n+33.o : 6«2)78 «¬­®J(X'­ ¯°±²³+3 +-ῌ,3.

´µ9 n,**0o : ¶:OU'('OH·}¸ z // +22ῌ+3..
Takano, B. and Watanuki, K. (+31.) : Lead-bearing barite from Kawarage mine, Akita Prefecture, Scientiﬁc Papers of College of General Education, University of Tokyo, ,., ,/ῌ-+.
n,**0 . 3  1 ' '(z¹º /3 »¹ ¼ o