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Some Considerations on the Research History of the Paleo-Ryoke Belt(+) Ichikawa’s Paleo-Ryoke Belt *ῌ**Ikuo Hara* and Takami Miyamoto**
Abstract : The Paleo-Ryoke Belt as a continent, which was ﬁrst proposed by Ichikawa(+31* in a viewpoint of geosynclinal orogeny, +32+ in a viewpoint of plate tectonics), is
now considered to be placed along the Median Tectonic Line in Southwest Japan andto have been amalgamated with the original constituents of the Ryoke belt (accretionary complexes developed in front of the Hida continent) in early Cretaceous.
Some tectonic models for its reconstruction have been proposed by many authors, now
being in hot dispute. This paper investigates how the di#erence between two tectonic
models, Model I proposed by Takagi & Shibata (+330, ,***) and Model II proposed byHara et al. (+33*a, +33+, +33,) and Miyamoto & Hara (+330), is related with theirunderstanding of Ichikawa’s papers.
Key words : Paleo-Ryoke Belt, tectonic model, research history, Ichikawa’s papers    ῌ ,***   !" #$ῌ%ῌ&,-.
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OYO CORPORATION., -῎+῎-*, Minaga, Saeki-ku, Hiroshima, 1-+῎/+,., Japan** ±&©©²2³´)µ¶}·¸¹
Department of Earth and Planetary Systems Science,
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7 d 89' +33. >+  
6' :1 +30- @ +31* 6' GH  ef; <+g h i)j'& k l=1e% & +)3' >"* A)",>?6V*+,J* mn4n T) - @oAB"CD$ EDpqF(rq' G[[ stu";n vw  Hrq6xyzI/J"' MRῌ %&'1{V*6' @ +31*
KI|-L";!E,$T' c +GH )c f; ῌv}?
~ X8 Xp "J
M$ 6N6ῌ ῌΐῑῐ῎῍ ῏ῒ῔Key words @ +31* 6";*,' + O +P', PQ" H  * %& ' - P* % & #"RS)  ! ' . &@U)$(' / QqFT
T' % & 4 Key words  ῌ'῍' ῎ .nV@";'
Eocene 'W6xX ' Key words
῏  ῐ 6Y# '&ZW+"> 
MTL RSvw *  H">% & 6
"- U
6Jn)  Late Cretaceous ". MTL RS  "[$ % & 6' Eocene  
' @ +31* \+]!
& ("J* [> ῒ^ῒ_` ab6 &!  %I)c)
e.g. Kojima, +3/- @ +31* qF)F2) 6' UQ&Jd magma front G
HQqFT#  d * ' d+' e >@ fg ("cRS"CD* Uhi Mesozoic shear zoned
Benioff zone d"> U*j
' MTL >lS
k' Late Cretaceous ";R ' 
 6 R' RS6 MR \Pc _`ῒ^ ab6' Q&J
d m"ZW++mn & MR ' ' Q&Jd"nZW+jk'+o 1V* P
MR Q&Jd6¡ > A Permian¢Triassic "' >@* [H$ : U%vpῌ£q ,*** ¤>"r& q67' & q <R\l=*I' c )s¥ "t$x¦)*6- ' %% & e% &@ou & P ¦v' & l=1
Tw2' +33+ * §E+mne$ 4' `xyuv+z¦ 6{* d   5 |¨J6 & q ,|**' ª«¬«­
6©!})"*>"' @ +31* ' %MR '  Q&Jd"'&magma front E®>RS' *6- MTL >
RS' & q6765 " 
' 5 6 & l=1 ") ' 5 c6 & +*6- ' vpῌ£ql=1" ,*** b)"\",~' **' 5  &n T)
l=1 +V*$ ,- ' <¯.nEn , °± ,G$ zI,,I  *  "' @  +31*  U   % & dMR  U d   "6 
U d 6' UQqFTC&",* >'  S'" H*' qF'" #" MR ῌ²ῌ d .n"> ,+³$>"$ T' MR  MTL RS"´ ' vp ῌ £q +330'
 8
,*** "> @ +31* % & [\ vpῌ£q ,*** ¤" : U&  µ"qF'"¶ ' GH H ῌ ²ῌ mB1"*,***' ·K"  % & d 
[\6' % & ῑ"N6-¼ 13 ¼

, º¹ῌ»5ºd       
 !" :  #+31*$  # $ %  MTL  MR 
&'(" )*+,+ -.+/)0   1
  #+31* *$  2!"#3$%
4 +5 &'(  shear zone 6)7
08(*0 &'9+:1,;- .
/ 0 01 #cf. Miyashiro +301$ 10<23456=>?@A+
7BC07 'DEFG89 HI7J0:; #Matsumoto +302 ; 6<K +303 ;Ozima et al., +301 B L$ M   N  O = magma front PQRS>?-@ 0
AT  )NO=BU H)UC
V&WD MR X" EY)) MR   " )
 #+31*$  MTL C3 R 0Z   #+31*$ F G [
CVH  )B5 [CVH
7\70 IJ9]^ K_#+33* +33+$ 7LMU ))0 )N`
% abῐOS>?cPCVH0! 
C3 [CVH0dQ ῍e4 RSf9
dT῍UV0BU #K_ +33*
+33+ ; ,K +33+ ; Hara et al., +33,$,ῌ ΐ῔῍ῑῌῐ῎ῑῒ῎῏gWῌXY #+330$   h i%  MTL 5jZ[\!k7]^B_` + J UC52lmBaHb 0cdM)cd nopF
eqrqH%fCVH0*HfagBhi#k^
s=^jt! ( %+31* ; Takagi +320$ 0AT   #+31*$ [CVH Z.l9Bmun>_opqh97B ))0 qv #+31,$ Yῌrs #+31-$ 9wtu #+32*$ 45vwS>
xx y1z{xx῎ qy)0 #, +33- |z$ : k^ Yῌrs *H5 [{`5|munhUq^ 0AT qv}H9~H   +N_}~EF8
0AT   #+31*$  n
opFeqrqH%fCVH0*H 0xx.-@ B  #+31*$  CVH0*HaH0dQ B CVH0HaH0 
ῐ}ῐH  wtu #+32*$ S>  +32* ῏ 3eqrqU 5! 0dQ!
BU nopFῌFopqU [CVH"BU +32+ z #Ichikawa +32+$ )) [CVH ῐ}ῐH mun9 #[CV ῐ } ῐ H 
$ 0 mun>_9nopFῌF
N mun0 $ m 
Ichikawa #+32+$  #+32,$ 0U  B% 0 [CVH^0! ῌ ῐ}ῐ
H 3p7)0 ῍ ῌ}H3THI0q9pFῌm 879[n5
#Kano +313 ;  +32, BL$ B9 'p
@pF BL ῎ g+0 *+5 ¡nopFeqrq
Sf ¢Q ῏ £¤¥*HHI¡ῌ
89BB)0U [CVH ῏Hp7Jῐ}ῐH 
 #[CV $   )[CV 3
9nopFeqrq 1BU *+5!07
 #+32,$  [CV ῐ}ῐ
H &eqr¢  
MTL 1¦?BC 1§¨ g£¨¥0 G!  ©N0U MTL¤iª@¥¦"¨¥U #Ichikawa
+32*$ gW:IJ90U 7LMU #e.g.
,K +311a +311b ; Hara et al., +32* ; Takagi
+320$ ῍YBq CVH3§¨©n0 MTL 5«£ª@ª¬! , +32* ­Ii{ ®«ῐ*¬$­CVH*H¯  mH °®±+K¯+"
ª@ .+ d° $²1S>³±´©)0µ #$² +320 +321 +323 +33*
; Sakakibara et al., +323 ; ῍,K +33*$ U
 MTL 7 &eqr²° MR.¶  ) Ichikawa #+32+$  #+32,$
[CV ³´G
 #+31*$ 10LM  #+32,$ %  MTL CV&WDK¯3§µ¨¥ *H MR  D¶Dῌ·p FoE¸  1* CV&W
D9·[CV '.0¹¸70
 MR 0Z! R #CVH$ 0Z! B
 1   #+31*$ 10LM MTL ¼ 14 ¼

Y_ ­ ./ »]^¬?ºPQ ῌ

MR 
  Ichikawa +32+      +32,   




! "#῍῍῍$%&'()' *+,-&./0-& .!12 ; Ichikawa +33* ;Mizutani +33* (")#34$ 5ῌ5%&'6
7$ 89: ; <  
)(=(>( 4$ )*>?@)'A$ MTL +,B('60D . ./C $ 
+33* +33+ EF +33+ Hara et al. +33, 
12  -    +31* 3G45 Ichikawa +32+ +32,  HI6JKL5ῌM7
5A(N >O  89:)PQ
( RS 7$ 89:O)PT U  V WX; ῌ Y<;  Z[ +32* "\=89]^ _>??@ T>  +32, @ MRῌI?@AB;
CG?@   HI6J
KL5ῌM75I5?@  MRῌ
IAB;CG?@ (V `('V 'PT >  7  V$ aD E   VbF
 HI6JKL5ῌM75
I5?@  MRῌIAB;CG'6GH?@`(' V  
Ic B<  (<Jd K )Le$ fg! M '
e >F bF >hi  fg!
M(>(7 !jH bF>
Ichikawa +32+   +32,  8 9 :  
kEarly /Middle Jurassicl  mn
opqNere O< ( PI
5s)QRS!12stT'6G(>(  +32, U )6
e$ : k*+,-ῌVW=uXYSmZ[v[\] wῌ^_ uXYxy
3uXY[m+\z{|p},}q~: s QRSY`2s vabF +32+ @ Ichikawa +32+ c tdef{no }s  Ivab.?Ig>( V QRSvabF46(7$l V k0-efh+ij  .
klms)e;n)>(l /C   Matsuda and Uyeda +31+  n)>'I>Oklm 6G(n( $>ofp' (  V qr"stuT vw
' >( -=#xyB(I5z[klm&6 &. {  z{῍+pz{|") kI&[}~n5n p "
V  ,*Ma  

+33* "Z>  Hara et al., +33*a,+33,
nopqῌ q }((T +32,  B( !1n2
i῍ Uemura and Yokota, +32+ ; V
Hara +32, ; IRGS +32+ ; QR
+32+ F +32+ ) + A¡)
¢( £) s!1¤n2 ¥;> ` A(Ig¢> T; "#῍῍῍B( |¦A £) , !1n  +32- "    § +32* B=45 Ichikawa +32+ +32, B('!12 >B<¨ Seely
et al. +31. Coney et al. +32* >©)P> 89:;>'OZ>(Ic  Y_f1T qª|4t
qr"st !1n2) ¥;>':O]^9 g«
V >Fe)PT  +32* "\= 
+32* "\= Ichikawa +32+  +32,  J¬Vd25I5s?u nopqNereS, m QRS!12s+,
uXmnopqNerek0-efh+mijklms)e l ($U ) U> V­®) ¯F ,*** °6
$ : k¡¢ +32- I῍±²£66
 M75 ³:´-qr")($g« EF +321  µ¤D῍¥¶DY·I῍±²£6*+,-!1 6¦#
+32. .J¬5 § +320 ³:´-!
1)'6  QRSQR+!1e.g. F +32+ ; ¨©F2;nf +32- ; Yao +32. ; | +32/ ; ª¸ +32. u # +312 ; «¹F
Xnf¼ 15 ¼ »ῌ®|

+313 ; ῌ +32. 
ῌ  +0* Ma  ῌ
  +321  ! "#$% &'(+) *  & #$%+ ,-  . #/01!234$356
7$%  +321 8 &  #$% 9#+ ,- :;4 & <=#$% *8  >
?@ A *  >B CDE
4 FG
HIHJ@  !KL+,- M'?N3#O!$%/ 6 ": #$ P%8 >B!QR A#
8&'3' B(S῍T )!*)/% +,8?N3῍)/%U-VW8N36 A
3X  +321 8 >B#B(S# Y./Z%8/ ' Hara et al. +33*a[8 >B!&*#\] A *!(S# !῍^2 #QR%/36 MTL_`aῌ091bU-B(SY.
23'/#QR%/34[? 6 T B(S!U ? 2 #QR J0N3 8 4c
+33* 56$%4[?@ +33+ 7bd[ !*/%[ +33+ Hara et al. +33,
?N36 A 3X Hara et al. +33, !*[8 (S# !῍^*! & ῌ B(S*eKῌ* #\fg [? 6AA[89A#8 +32* 7h:8 ;i<[8? #$%2 j!=kglmB(S e  ' HIfg* #  n >-9Yo῍MR ῌ  ῍!?R@3A#
  pA'QR4Z J0N%/3B[ T +31* +32, Ichikawa +32+ q#8;
krsN%/3A#[? 6 7Z8t3 C+30-
 uDD5 #/0vE wF
eGx#8Hrs yI U-9-JK!LR@ 2z?N3#v0A#[2? 6 7Z8 + )8 *#7 MNM{Z ,-' :;!2)M[=Z #v0A#[?|0#  +321 8QR A#'&'3A#[? 6 A
3X  }~O}W,} ,}&9w}&9ῌ #/0PG
9!QR{l 23'  J0YScT4
U T[3{Z%k3A#8 *  >Be &ῌB(S* VRR-A##QR4Z3 [? 6 7Z$ W.=% +,-!9.
: wF X.Y#CDZw e.g. Banno &Sakai, +323 ; Hara et al., +33*b 4
HIHw[9 \RmSuppe +31,
two-ways street  Cloos &Shreve +322
subduction-channel ']"2 #QR4Z 2z'tZ #$4#N%
2 ,- PG9 1^_-!`4$
e.g. Hara et al., +33*b, +33, ;3A#'4Z
ῌ +3306
A J0$% C +30- T +31* +32,' (S+a B(S#\fgTb8 +,- /%cB(S ῌ&ῌ 9vE[{Z3 d". #QR@ pA'tZ3[? 6 7$%t3 +32* 7h:bd8 u  8 MR Ck@AtZ
35 #/0T +32, ' e{Z3#4
Z TCf23'`4{Z[? : B(S*'J,-gh$32 #.Zm ghi8
7 MN
HIH[M{Z))?
27 ¡j!¢$3pA'? ##$48Q
R4Z3 Hara et al., +33*a ;  +33+6 £D ¤ek +* kb fl ; e.g. Enami, +32- ;  +32. 8 m¥n ¨op ῌqCT¦_£§r ῌSs ῌStuc ek +/_+1 kb fl; e.g. Takasu, +323 'f4[©v$%/ 6©v'AN3: ¤ =ªw'
Takasu +3236 Hara et al. +33*a
AN%/+33,  +33+ ῌ +330 8 A m¥ CT¦_£§ n8 HIHhanging wall !9$%/3B(S*[?@ ©
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Z<y¬ +311a ¦ tµ  ¥­k¦ ' ¶®GsV¯³ -*3῍-3*$) ±} ῌ C·¶t ῌ °¸@ ῌ (< ± ῌ Z<y¬ῌ ¥ +32. I}9¹²³}9῍¼ 17 ¼ῌ»
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