戸賀船川図幅の珪藻

(1)

- 1 -

5 万分の 1 地質図幅「戸賀及び船川」地域（男鹿半島）

の新第三紀及び第四紀の珪藻化石層序資料

柳沢幸夫

*

_{・渡辺真人}

*

Yukio Yanagisawa and Mahito Watanabe (2011) Data report of the Neogene and Quaternary diatom

biostratigraphy in the Toga and Funakawa Districts, Oga Peninsula, Akita Prefecture, Japan.

Open-File

Report of the Geological Survey of Japan, AIST, no. 533, p. 1-17.

Abstract: A high-resolution marine diatom biostratigraphy is established for the Neogene and Quaternary

sediments distributed in the Toga and Funakawa Districts, Oga Peninsula, Akita Prefecture, northeastern Japan.

In this report, the biostratigraphic distribution and quantitative abundance of marine diatoms are documented

from the Neogene Nishikurosawa, Onnagawa, Funakawa, Minamihirasawa and Nishimizuguchi formations

and the product of Toga Volcano (middle Pleistocene).

Keywords: diatom biostratigraphy, marine, Miocene, Pliocene, Pleistocene, Neogene, Quaternary, Toga,

Funakawa, Oga Peninsula, Akita, Japan

*

_{地質情報研究部門}

_{地球変動史研究グループ（AIST, Geological Survey of Japan, Institute of Geology and}

Geoinformation）

要旨

地質調査総合センター発行の

5 万分の 1 地質図

幅「戸賀及び船川」地域の地質（第

2 版）の作成

に使用された珪藻化石層序データの詳細を報告す

る．本報告では，中新統の西黒沢層・女川層・船

川層，

鮮新統

下部更新統の南平沢層・西水口層，

それに中部更新統の戸賀火山噴出物から産出した

海生珪藻化石の層序学的分布と産出頻度を記載す

る．

１．はじめに

本報告では，産業技術総合研究所地質調査総合

センター発行の

5 万分の 1 地質図幅「戸賀及び船

川」地域の地質（第

2 版）（鹿野ほか，2011）の作

成に使用された珪藻化石年代データの詳細を記載

する．これらのデータは膨大なため，図幅の報告

書には掲載できなかったため，地質調査総合セン

ター研究資料集として報告するものである．

２．地質

「戸賀及び船川」地域は，秋田県の男鹿半島

に位置する（第

1 図）．本地域には，暁新統から第

四系にわたる堆積物及び火山岩類などが広く分布

する（鹿野ほか，

2011）．このうち，本報告書で記

載するのは，中新統の西黒沢層・女川層・船川層，

鮮新統

下部更新統の南平沢層・西水口層及び中

部更新統の戸賀火山噴出物から産出した珪藻化石

である．なお，層序の詳細は図幅の報告書（鹿野

ほか

2011）を参照されたい．

西黒沢層は海浜から沖合にかけて堆積した礫岩，

砂岩，

シルト岩などからなる中部中新統である（第

2 図）．上位の女川層との岩相境界は漸移的である

が，海緑石や炭酸塩が珪藻殻などの生物源シリカ

とともに産出する層準までが西黒沢層とされる．

珪藻化石は本層の最上部のみから産出する．

女川層は珪藻質岩と珪藻質岩が続成変質して

生じた珪質岩を主体とする中部

上部中新統で，

酸性凝灰岩や細粒砂岩の薄層を挟む．

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- 2 -

船川層は，無層理暗灰色泥岩・シルト岩からな

る上部中新統である．

南平沢層は凝灰質泥岩・シルト岩に酸性凝灰岩，

もしくは凝灰質砂岩の薄層を多数挟む岩相からな

る下部鮮新統で，最上部に南平沢凝灰岩を伴う．

西水口層は，上部鮮新統

下部更新統の泥岩・

シルト岩で，厚さ

10 cm 未満の凝灰質砂岩薄層を

挟む．

戸賀火山は男鹿半島西端の戸賀湾（第

1 図）に

位置する開析が進んだタフリングで，火口内では

厚さ数

数

10 cm 前後の凝灰岩，軽石火山礫含有

凝灰岩，軽石火山礫凝灰岩など，タービダイトに

類似した堆積構造を示す堆積物が累重し，火口の

中心に向かって緩く傾いている．

３．試料及び方法

試料を採取したルートと地点は，第

1図に示し

た．また，各セクション・地点の層序学的位置を

第

3図に示した．今回検討したのは真山（Sn）セ

クション（第4図，第5図），西黒沢南方の地点16’

（第

6図），同じく地点17（第7図），戸賀湾塩浜の

秋田大学戸賀臨海実習所南側の沢沿いの地点

20 （第8図）と同じく地点Tg（第9図）である．

珪藻化石試料の処理と珪藻の分析・計数方法

は柳沢（1999）に従ったが，試料が多いため，一

部の試料では珪藻殻のカウントは

50個に止めてい

る．珪藻化石帯区分と生層準は

Akiba (1986)と

Yanagisawa and Akiba (1998) の NPD と D コード

（

D10-D120）を用いるが，珪藻年代はWatanabe and

Yanagisawa (2005) を用いて一部修正している．ま

た，生層準の年代は，Gradstein et al. (2004)の地磁

気極性年代尺度に合わせた．

４．結果

珪藻化石の分析により明らかとなった各セク

ション・地点の地層の年代分布を第

3 図に示す．

各セクション・地点における珪藻化石層序を第

5 図から第

8 図に示す．また，珪藻化石の分析結果

を第

1 表から第 7 表に示す．なお，結果に関する

議論は図幅の報告書（鹿野ほか，2011）を参照さ

れたい．

文献

Akiba, F.（1986） Middle Miocene to Quaternary

diatom biostratigraphy in the Nankai Trough

and Japan Trench, and modified Lower

Miocene though Quaternary diatom zones for

middle-to-high latitudes of the North Pacific.

In Kagami, H., Karig, D. E., Coulbourn, W. T.

et al., Initial Report of Deep Sea Drilling

Project, no.87, 93-480.

Gradstein, F., Ogg, J. and Smith, A. (2004) A

Geologic Time Scale 2004. Cambridge Univ.

Press, Cambridge, 589p.

鹿野和彦・大口健志・柳沢幸夫・粟田泰夫・小林

紀彦・佐藤雄大・林信太郎・北里洋・

小笠原憲四郎・駒澤正夫 (2011) 戸賀及び

船川地域の地質（第

2 版）．地域地質研究

報告（5 万分の 1 地質図幅）．

Watanabe, M. and Yanagisawa, Y. (2005) Refined

Early Miocene to Middle Miocene diatom

biochronology for the middle- to high-latitude

North Pacific. Island Arc, 14, 91-101.

柳沢幸夫（

1999）金沢市南部地域に分布する中新

統の珪藻化石層序．地調月報，

50, 49-65．

Yanagisawa, Y. and Akiba, F. (1998) Refined

Neogene diatom biostratigraphy for the

northwest Pacific around Japan, with an

introduction of code numbers for selected

diatom biohorizons. Jour. Geol. Soc. Japan,

104, 395-414.

図表のリスト

第

1 図珪藻化石層序を検討したセクション・地点の位置図．

第

2 図「戸賀及び船川」図幅地域の新第三系及び更新統の年代層序

第

3 図各層序セクションの年代分布．

第4 図真山ルートの試料採取位置図．

第

5 図真山ルートにおける主な年代指標珪藻種の産出

第6 図地点16’における主な年代指標珪藻種の産出

第

7 図地点17 における主な年代指標珪藻種の産出

第8 図地点20 における主な年代指標珪藻種の産出

第

9 図地点Tg における戸賀火山噴出物の詳細試料採取位置図と柱

状図

第

1 表真山ルートの珪藻化石産出表（１）女川層

第

2 表真山ルートの珪藻化石産出表（２）女川層・船川層

第3 表真山ルートの珪藻化石産出表（３）南平沢層・西水口層

第

4 表地点16’の珪藻化石産出表

第5 表地点17 の珪藻化石産出表

第

6 表地点20 の珪藻化石産出表

第7 表地点Tg の珪藻化石産出表

図版

1 地点Tg の戸賀火山噴出物から産出した珪藻化石．

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!"#$%&'()*

+,-./0

1 12&

5

1 34567894:;7<=)*

Fig. 1 Map of studied area showing location of stratigraphic sections and localities.

16'

17

20 Tg

Sn

1km

142°E 140°E 41°N 40°N 39°N

Akita

. 38°N

Oga

Peninsula

Sn

4

5

1

3 16'

6

4

17

7

5

20

8

6 Tg

9

7

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 C3 C3A C3B C4 C4A C5 C5A C5AA C5AB C5AC C5AD C5B C5C C5D C5E C6 C6A C6AA C6B C6C C1 C2 J C O R Aquitanian Burdigalian Langhian Serravallian Messinian Zanclean Piacenzian Gelasian Calabrian Ionian * C2A 1 2A 2B 3A 3B 4Bb 4A 5A 5B 5C 5D 6A 6B 7A 7Bb 8 4Ba 7Ba D65 (8.7) D60 (9.3) D56 (10.0) D55 (11.4) D51 (12.7) D45 (14.5) D40 (15.9) D35 (16.6) D30 (17.0) D25 (18.1) D20 (19.9) D10 (23.1) D75 (6.5) D80 (3.5) D50 (13.1) D70 (7.7) D47 (14.1) D77 (5.6) D85 (3.0-3.1) D73 (6.8) D77.5 (5.4) D68 (7.9) D66 (8.5) D59 (9.4) D57 (9.6) D58 (9.5) D55.8 (10.2) D55.(11.2) D54 (11.6) D53 (12.3) D52 (12.4) D48 (14.1) D44 (14.6) D33 (16.7) D43.2 (15.2) D43 (15.4) D42 (15.5) D41.5 (15.6) D41 (15.8) (3.9) 9 10 11 12 D90 (2.7) D100 (2.0) D110 (1.0) D120 (0.3) D95 (2.2) D105 (1.9) a b a c CN10 a CN7 CN6 b a CN4 CN3 CN2 CP19 CN11 b CN9 CN8 CN5 CN1 b a (Ma) CN15 b CN14 CN13 d CN12 a b c a b 1 2 (265) 3 (451) 4 5 (853) 6 (987) 7 (1128) 8 (1182) 9 (1219) 10 (1392) 11 (1706) 12 (1763) 13 (1990) A (2.75) 1 2 5 10 20 N.4 P.22 N.5 N.6 N.8 N.7 N.9 N.10 N.12 N.14 N.13 N.11 N.15 N.16 N.17 N.18 N.19 PF1 PF2 PF3 PF4 PF5 PF6 N.21 N.22 Globorotalia inflata beds PF7 Neogloboquadrina pachyderma No. 2 G. inflata bed PF8 PF9 _{No. 1} Neogloboquadrina asanoi bed Globorotalia ikebei bed = FO Neogloboquadrina pseudopachyderma FO G. peripheroacuta FO Orbulina Plancktonic Foram. Sharp Surface Miogypsina, Operculina No. 3 G. inflata bed !"# 20 15 10 5 3 2 1 4 FO Warm water diatoms Marker A FO M. echigoensis LO S. compressa Blue zone O-1 O-2 O-3 BF5 BF4 BF3 BF2 BF1 3 2 1 5 10 15 L U $ % & ' ( ) * ' ( ) + % , -. / , 0 1 2 3 4 3 & ' 5 6 ( * ' 5 6 ( 78 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 9 : 3 ; <=; 2 3 ; > ? 1 ; , @ A ; B C ; DE; F3; , 0 1 ; GHIJKLMNOP QRSTU-SVSWX YZ[\S]SWX \S]S ^_`ab c.TdefJT]S g.T]SWX efJThSd c.SdiTSWX Zjc]S Zjc]S iTSdiTkS ilSdilTkS Zjc]S mmilThSdkS n.og.ThSdkS d]Spqrsg.S >?1g.S .og.TkSdhS Ak3 t,; g.T]SkSu; ]TkS g.T]SWX 43; ]SWX Zjc]S vTwx y x (Ma) 0 v z { | s } f ATNTS2004 _il ~ c NPD ; (Ma) c.T ~c ~ c ; (Ka) s Blow (1969) % (1978) `` ; Matsunaga (1963)

;

*

pq43v

v

24 0 24 D105: FO Proboscia curvirostris D95: FO Neodenticula seminae (closed copula) D85: RI Neodenticula koizumii D77.5: LO Thalassiosira temperei ¡¢ FO £¡¢ LO ¤¥ RI il~c; ¦§ t ¨© Sª «

BF5: Cribroelphidium yabei Zone BF4: Uvigerina akitaensis Zone BF3: Miliammina echigoensis Zone BF2:Spirosigmoilinella compressa Zone Upper: Spirosigmoilinella compressa - Martinotiella communis Zonule Lower: Dorothia sp. - Cribrostomoides renzi Zonule ("Hapro-Dorothia zone")

BF1: Hopkinsina morimachiensis Zone (Hopkinsina / Sigmoilopsis Zone)

~c

!"#$!% &'()*+,-

2 ./

012*+,-)

2011

.3456/

2011

Fig. 2 Chronostratigraphy of the Neogene and Pleistocene sequences in the Toga and Funakawa Districts.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 C3 C3A C3B C4 C4A C5 C5A C5AA C5AB C5AC C5AD C5B C5C C5D C5E C6 C6A C6AA C6B C6C C1 C2 J C O R Aquitanian Burdigalian Langhian Serravallian Messinian Zanclean Piacenzian Gelasian Calabrian Ionian * C2A 1 2A 2B 3A 3B 4Bb 4A 5A 5B 5C 5D 6A 6B 7A 7Bb 8 4Ba 7Ba D65 (8.7) D60 (9.3) D56 (10.0) D55 (11.4) D51 (12.7) D45 (14.5) D40 (15.9) D35 (16.6) D30 (17.0) D25 (18.1) D20 (19.9) D10 (23.1) D75 (6.5) D80 (3.5) D50 (13.1) D70 (7.7) D47 (14.1) D77 (5.6) D85 (3.0-3.1) D73 (6.8) D77.5 (5.4) D68 (7.9) D66 (8.5) D59 (9.4) D57 (9.6) D58 (9.5) D55.8 (10.2) D55.(11.2) D54 (11.6) D53 (12.3) D52 (12.4) D48 (14.1) D44 (14.6) D33 (16.7) D43.2 (15.2) D43 (15.4) D42 (15.5) D41.5 (15.6) D41 (15.8) (3.9) 9 10 11 12 D90 (2.7) D100 (2.0) D110 (1.0) D120 (0.3) D95 (2.2) D105 (1.9) ! " ! (Ma) 0 # $ % & ' ( ATNTS2004 _)* + , - ./0 (Ma) 1 23456* 1 2 5 10 20 7 8 9 : ; < ; = > ? @ A B > ? @ A CD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 E F ; / GH/ : ; / I J 9 / 7 K L / M N / OP/ Q;/ 7 8 9 / RSTUVWXYZ[ \]^_`â^bc defg^h^bc g^h^ ijklm ,nop(Uh^ qnh^bc p(Urô ,nô)^bc es,h^ es,h^ )ô)t^ )*ô)*t^ es,h^ uu)*rôt^ vnwqnrôt^ oh^xyz&qn^ IJ9qn^ nwqntôr^ Ak3 {7/ qnh^t^|/ ht^ qnh^bc <;/ h^bc es,h^

Tg

}~V`[

Sn

`

16'

17

20

! " ! (Ma) 0 # $ % & ' ( ATNTS2004 _)* + , -NPD ./0 (Ma) /

/

1 23456*

}~xy<;

16

24 0 24 D105: FO Proboscia curvirostris D95: FO Neodenticula seminae (closed copula) D85: RI Neodenticula koizumii D77.5: LO Thalassiosira temperei FO LO RI )*+,./0 ^ 16 /'t

!"#

3

1 $%&

Fig. 3 Chronostratigraphy of the studied sections.

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69 65 70 55 50-52 48,49 40 41-44 01-28 29-39 78 79-81 82 87 88 89 90 91 92 93 94 60

0 200 m 38 39 33 34 35 36 37 29 3031 32 10 m 01 05 10 18 19 22 23 26 28 0 m 5 m,gl,lam,7 82 83 0 5 8 m sl-vf,gl,30 f,gl.35 sl+f,gl,wavy,30 84 85 86 87 Sn-m,gm,lam,25 79 80 81 0 3 m f-vf,gl,1.5 vf-sl,gl,4.5 vf,gl,0.5 vf,gl,4.0 vf,gl,16 vf sl,gl,2 01 05 10 15 20 25 28 0 5 8 m

Sn Sn Sn Sn Sn !" !" !" !" !" !" !" !" #$%$& m: '$%$& f : ('$%$& vf: )$& sl: *+," gl: -./0-12" 3456789 :;<= gm: cm

Sn

4 Fig. 4 Map showing sample locations in the Shinzan stratigraphic section.

> > > >

(7)

41 0m 50 100 150 200 250 G G G 01 10 20 30 35 39 40 45 50 52 53 55 60 65 69 70 78 79 81 82 87 88 89 90 91 92 93 94 Sn Denticulopsis simonsenii

Denticulopsis vulgaris Denticulopsis praekatayamae Denticulopsis katayamae

Thalassionema schraderi Thalassiosira temperei Thalassiosira marujamica Thalassiosira singularis Thalassionema antiqua Rouxia californica Thalassiosira castanea Azpeitia komurae Nitzschia pliocena Nitzschia rolandii Neodenticula koizumii Cosmiodiscus insignis Thalassiosira zabelinae Cavitatus jouseanus Cavitatus linearis Thalassiosira Hemidiscus cuneiformis Rhizosolenia bergonii Neodenticula kamtschatica Denticulopsis dimorpha var. dimorpha Denticulopsis dimorpha var. areolata convexa var. aspinosa 7Bb 7Ba 5D D77 (5.6) D75 (6.5) D73 (6.8) D70 (7.7) NPD D77.5 T. temperei (Ma) D57 (9.6) (5.4) D60 (9.3) D65 (8.7) D68 (7.9) 6A 6B 7A 8 D80 (3.5) D66 (8.5)

t t t t s s t t t t 0 % 50 s t G ! ! " #$ %&'" ()* ()* +,- . ' / 0 1 23 ? D77.5 FO miocenica +

4$

Sn

!"#$%&'()#$*+,-

5 Fig. 5 Stratigraphic distribution of marker diatoms in the Shinzan stratigraphic section with diatom zones.

Thalassiosira oestrupii

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Denticulopsis simonsenii Denticulopsis vulgaris

D55 (11.4) D53 (12.3) D50 (13.1) D52 (12.4)

NPD5C

NPD5B

NPD4Bb

(Ma) 0 50%

!" #$%& #$'(

0

1

2

3

4

5 6m

Denticulopsis hyalina G g g g g G g 01 05 10 15 20 25 30 34 16'-

)*16'

6 16'

!"#$%& !'()*

Fig. 6 Stratigraphic distribution of marker diatoms at site 16' with diatom zones.

Denticulopsis praekatayamae

Denticulopsis katayamae Thalassionema schraderi

D60 (9.3) D59 (9.4) D57 (9.6) D58 (9.5)

NPD6A

NPD5D

(Ma) 0 30% !" #$%& #$'( G g

0

5 10m

G g G 21 25 30 35 40 45 17-

)*+,

7

17 !"#$%& !'()*

Fig. 7 Stratigraphic distribution of marker diatoms at site 17 with diatom zones.

Denticulopsis praedimorpha minor var. D. praedimorpha var. praedimorpha Actinocyclus ingens f. nodus Denticulopsis dimorpha var. dimorpha Denticulopsis dimorpha var. areolata

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01 02 03 04 05 06 07 08

Denticulopsis simonsenii Denticulopsis vulgaris Denticulopsis katayamae Thalassionema schraderi Nitzschia pliocena Thalassiosira temperei Rouxia californica

Togawan NPD6A NPD5C NPD6B 0 10 Aphrocallistes sp. (m)

8

20 !"#$%& !'()*

Fig. 8 Stratigraphic distribution of marker diatoms at site 20.

122 123 124 125 126 127 0 4 m Oga- ! "# $%&

'

Oga-122,123 Oga-124,125 Oga-126,127 8

() !*+,

Tg

-./ ()01 2345()6789:;<=>

9 Tg

+,-./%0#1234567&89*

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Fromation Diatom zones Diatom biohorizons

Sample numbee (Sn-) 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Original sample number (Oga-) 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Registration number (GSJR-)

97238 97239 97240 97241 97242 97243 97244 97245 97246 97247 97248 97249 97250 97251 97252 97253 97254 97255 97256 97257 97258 97259 97260 97261 97262 97263 97264 97265 97266 97267 97268 97269 97270 97271 97272 97273 97274 97275 97276

Preservation P M P P P P M M M M M P P P P P P P P P P P P P P p P P P P P P P M M M M M G

Abundance R R R R R R R C C C C R R R R R R R C R R R A C R R A R A R R A C A R C A A A

Actinocyclus ellipticus Grunow + 1 1 2 1 1 1

-A. ingens f. ingens (Rattray) Whiting et Schrader 10 3 5 4 9 3 5 9 3 2 - 4 - 2 - 4 7 27 20 57 55 51 51 41 39 30 49 45 72 43 35 30 - - - - 1

A. octonarius Ehrenberg

-A. sp. A (cf. normanii ) 1 1 1 1 2 1 1 6 1 1 1

-Actinoptychus senarius (Ehrenberg) Ehrenberg 14 10 6 11 4 3 2 9 5 8 11 5 6 3 6 3 3 + 3 3 - 2 1 12 6 4 - 2 2 2 3 4 2 21 7 4 1 16 25

A. vulgaris Schmann 1

-Aulacoseira spp. 2 1 1 2 1 1

-Azpeitia endoi (Kanaya) Sims et Fryxell 4 1 2 2 1 2 + 2 1 1 2 + 4 11 6 8 3 3 3 7 4

-A. nodulifera (Schmidt) Fryxell et Sims 1 1 + + 3 2 1 4 3 + 2 3 1 2 1

-A. vetustissima (Pantocsek) Sims 1 1 1 4 4

-Cavitatus jouseanus (Sheshukova) Williams 1 + + + + +

-C. linearis (Sheshukova) Akiba et Yanagisawa - - - - 1 - 1 - - +

C. miocenicus (Schrader) Akiba et Yanagisawa + - - + - - - + + - - - + - - - + 1 + + - 1

Cocconeis spp. 1 1 + + + + 1

-Coscinodiscus marginatus Ehrenberg 6 5 1 6 8 7 11 10 9 6 14 26 15 11 19 11 20 46 44 18 22 8 16 15 22 27 22 10 8 6 30 2 21 4 29 31 25 16 21

C. spp. - - 1 - - - - 9 - - - +

Delphineis surirella (Ehrenberg) Andrews + 1

-Denticulopsis crassa Yanagisawa et Akiba + 1 + +

-D. crassa var. 1 +

-D. dimorpha var. dimorpha (Schrader) Simonsen + + + + + + 1 1 2 + + 1 +

-(Closed copula) 2 + + + + + + 1 1 + + 1 1 1 1 1 7 3 1 3 3 3 3 2

-D. dimorpha var. areolata Yanagisawa et Akiba + 1 1 +

-(Closed copula) 3 + 3 10 11 + 5

-D. katayamae Maruyama + 3 4 9 10 3 4 3 1

-D. praekatayamae Yanagisawa et Akiba + 1 + 4 4 4 3 1 1 2 +

-D. simonsenii Yanagisawa et Akiba 1 5 6 2 + 1 + 1 1 5 3 + 3 9 1 3 1 - + - - - - 1 - - 1 + - + - - - +

D. vulgaris (Okuno) Yanagisawa et Akiba 5 4 3 2 2 1 1 3 3 4 1 3 + + 3 1 6 + 1 +

-D. vulgaris (Okuno) Yanagisawa et Akiba (broad) 2 + 1 +

-S-type girdle view of D. simonsenii group 3 6 2 3 1 + 2 3 5 1 3 2 4 + 1 3 +

-D-type girdle view of D. simonsenii group 4 3 1 1 1 4 4 + 1 2

-Diploneis spp. + 2 + + + + + + 1 1 2

-Eucampia sp. A (= Hemiaulus polymorphus Grunow) +

-Goniothecium rogersii Ehrenberg 1 + + 5 2 3

-Grammatophora spp. - - - - 2 - - - + - + + - - - +

Hemidiscus cuneiformis Wallich + 1

-Hyalodiscus obsoletus Sheshukova 3 1 1 5 + + 1 - + 2 - 3 2 3 4 4 2 1 + 1 1 3 - 2 2 4 1 1 1 1 2 1 - - 2 + 2 2 1

Ikebea tenuis (Brun) Akiba 5 3 + + 1 +

-Mastogloia splendida (Greville) Cleve +

-Nitzschia heteropolica Schrader - + - - - +

Paralia sulcata (Ehrenberg) Cleve 8 9 4 9 2 16 21 9 15 7 8 15 29 23 30 21 8 10 21 2 3 9 6 4 11 7 + 5 2 11 4 4 21 3 9 1 - 6 +

Plagiogramma staurophorum (Gregory) Heiberg + 1

-Proboscia barboi (Brun) Jordan et Priddle 12 8 7 8 24 18 38 12 8 4 6 2 9 5 6 12 19 1 4 5 2 4 3 2 2 5 1 2 3 9 3 41 38 21 25 34 20 42 9

Rhizosolenia hebetata f. hiemalis Gran 1 2 1 3 3 +

-R. miocenica Schrader 8 2 1

-R. styliformis Brightwell 3 2 2 2 2 1 1 2 5 1 1 1

-Rouxia californica Peragallo + - - - + - - - + - + - - - - +

Stellarima microtrias (Ehrenberg) Hasle et Sims - 1 1 - - - - 2 - 2 2 - 4 3 1 - 2 - + - - 2 - - - - 1 - - + 2 2 2 1 - - +

Stephanogonia hanzawae Kanaya 1 + + 1

-Stephanopyxis spp. 2 6 2 2 + 1 2 5 1 - - 2 3 1 - - 10 3 + - - 1 - 1 - - - 1 - - 3 - - - +

Thalassionema hirosakiensis (Kanaya) Schrader 2 + 2 2 4 + + + 1 2 1 1 3 2 + + 1 + + 2 1 2

-T. nitzschioides (Grunow) H. et M. Peragallo 20 22 46 34 45 39 17 28 44 50 44 23 19 22 21 32 15 6 5 4 10 6 7 6 6 5 2 3 3 13 4 1 5 15 7 2 2 4 10

T. schraderi Akiba - - - - 2 - - 1 + 3 3 5 - - - 2 1 16 9 20 44 5 31

T. cf. schraderi Akiba + +

-T. sp. A (pointed) - - - - 1 + + + + + 2 6 + - - 9 8 7 5 3 1 4 +

Thalassiosira leptopus (Grunow) Hasle et Fryxell 1 1 + 1

-T. marujamica Sheshukova + 1 1 1 1

-T. minutissima Oreshkina +

-T. temperei (Brun) Akiba et Yanagisawa - - - - 2 3 - + - 2 - 1 - + - + 2 1 3 1 - 1 + 1 - - - - - 1 - 3 2 1

T. sp. A +

-T. sp. B 1 2 2

-Thalassiothrix longissima Cleve et Grunow + - - + - - - - + - + - - - - 1 - - - - 1 - + - +

Triceratium condecorum Brightwell 1 -Total number of valves counted ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀

Resting spore of Chaetoceros 48 59 41 53 34 28 20 32 28 32 29 33 42 70 51 33 26 14 16 14 10 10 7 12 11 9 9 9 7 13 8 2 9 7 18 9 6 6 4

Preservation P: poor, M: moderate, G: good; Abundance R: rare, C: common, A: abundant

Onnagawa Formation

Denticulopsis dimorpha Zone (NPD5D) NPD6A NPD6B D57 D5

8

D59 D59.5 D60 D65,66

第1表真山ルートの珪藻化石産出表（1）女川層

(11)

Formations Onnagawa Formation Funakawa Formation

Diatom zones NPD6B NPD7A NPD7Ba

Diatom biohorizons

Sample number (Sn-) 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

Original sample number (Szn) 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Preservation P P P M M P G P M M P G M M G G G M M P P P G P P P P P P P

Abundance R C C C C C A C C A C C A C A C A C R R R R A C R C R R R C

Actinocyclus ellipticus Grunow +

-A. ingens f. ingens (Rattray) Whiting et Schrader 5 3 2 2 2 6 1 1 + + 1 1 1 3 3 2

-A. octonarius Ehrenberg 1 + 1 1 3 1

-A. sp. A + + 1 2 + 2 1 + + 2 + + 1 2 + 1 4

-Actinoptychus senarius (Ehrenberg) Ehrenberg 14 1 1 4 2 2 5 7 1 + 4 2 - 2 + 2 4 + 2 - 1 3 1 + 4 1 1 - 4 1

Arachnoidiscus spp. 1 + 1 1

-Asteromphalus spp. 2 1

-Aulacoseira spp. + 1 1 4 1

-Azpeitia komurae Akiba + + + 1

-A. endoi (Kanaya) Sims et Fryxell + + 1 +

-A. nodulifera (Schmidt) Fryxell et Sims - - - - 1 - - - - 1 - - - - 1

Cavitatus jouseanus (Sheshukova) Williams + + + + + + + 1 + 2

-C. linearis (Sheshukova) Akiba et Yanagisawa + + 1 + + + +

-C. miocenicus (Schrader) Akiba et Yanagisawa + + + + 1 1 +

-Coccineis califronica Grunow + 1 + + + 1 + 1

-C. costata Gregory - - - - 1 1 1 - 2 + + - 1 1 2 1 +

C. curviritunda Brun et Temp. - - - - - 1 - - - + - - - 1 + - - - +

C. scutellum Ehrenberg + + + +

-C. vitrea Brun + + 1 + 1

-Coscinodiscus marginatus Ehrenberg 43 75 62 33 58 72 13 82 77 80 66 77 71 34 9 30 43 78 59 73 74 76 19 77 74 78 70 29 52 63

C. radiatus Ehrenberg + 1 4 2 1

-C. spp. - - - - 1 + - - - - - 1

Cymatosira debyi Temp. et Brun 1 1

-Delphineis surirella (Ehrenberg) Andrews + + + +

-Denticulopsis hyalina (Schrader) Simonsen + + + + 1 1 +

-D. praedimorpha var. praedimorpha Barron ex Akiba 1 + +

-D. praehyalina Tanimura +

-D. simonsenii Yanagisawa et Akiba - + + - - - + - 1 - - - - 1 - + - - - + - +

D. vulgaris (Okuno) Yanagisawa et Akiba 1 + +

-Diploneis bombus Ehrenberg +

-D. smithii (Bréb.) Cleve + + +

-Grammatophora spp. + + + + + 1 1 + + 1

-Hemidiscus cuneiformis Wallich + + 1 + 1 + +

-Hyalodiscus obsoletus Sheshukova 1 + 1 1 + 1 + - 2 2 + 1 - 1 1 1 - 1 1 2 2 1 1 - - 2 1 1 3 1

Ikebea tenuis (Brun) Akiba + + + +

-Melosira sol (Ehrenberg) Kützing 1 + + + 2 + 1

-Neodenticula kamtschatica (Zabelina) Akiba et Yanagisawa - - - - 2 + + + - - - 2 7 10 5 18

Nitzschia fossilis (Frenguelli) Kanaya et Koizumi +

-N. grunowii Hasle +

-N. pliocena (Brun) Merz + + + + + 1 1 2 +

-N. rolandii Schrader emend. Koizumi + + 1 + + 1 + + + + 1 + + +

-N. suikoensis Koizumi +

-Paralia sulcata (Ehrenberg) Cleve 7 9 3 2 3 + 2 - 4 1 7 1 13 2 2 5 5 4 5 6 9 6 2 6 2 4 3 4 9 2

Plagiogramma staurophorum (Gregory) Heiberg +

-Proboscia alata (Brightwell) Sundstöm 1

-P. barboi (Brun) Jordan et Priddle 14 - 12 28 3 16 9 5 5 13 11 8 - 3 - 8 19 - 7 - 1 - 22 - - - 1 23 16 +

Rhaphoneis amphiceros Ehrenberg + +

-Rhizosolenia hebetata f. hiemalis Gran - - - - 1 - - 1 - 2 + + 1 1 - - - - 1 - - - - 1

R. miocenica Schrader +

-R. styliformis Brightwell + - - - - - 2 - - - - - 2 + + - - - - 2 1 - - - - 1

Rouxia californica Peragallo + + + + + + + + + + + + +

-Stellarima microtrias (Ehrenberg) Hasle et Sims 2 - - 2 + + + 1 - + + 1 2 2 + 2 + 4 1 1 1 1 + 2 1 2 - 1 - 1

Stephanopyxis spp. 1 1 1 3 3 2 1 4 2 3 2

-Thalassionema hirosakiensis (Kanaya) Schrader + + +

-T. nitzschioides (Grunow) H. et M. Peragallo 8 1 1 2 7 + 49 4 6 3 2 3 2 43 76 35 19 1 12 7 - 2 42 6 11 4 3 8 2 6

T. schraderi Akiba 8 7 14 23 21 6 10 + 1 +

-T. sp. (pointed) 2 1 + + + + + + +

-Thalassiosira antiqua (Grunow) Cleve-Euler + 2 2 + 1 2 2 + 1 1

-T. bipola Shiono - - - - 1

T. burckliana Schrader +

-T. castanea Akiba et Yanagisawa - - - - 1 - - - - 1 - - - - - 2

T. grunowii Akiba et Yanagisawa +

-T. jacksonii Koizumi et Barron in Koizumi + 2 5

-T. leptopus (Grunow) Hasle et Fryxell 1 +

-T. manifesta Sheshukova + + +

-T. marujamica Sheshukova 1 1 + + 1 + 1 + 6 10 6 + 1 1 2 2 2 2 1 1 2

-T. nidulus (Temp. et Brun) Jousé 1 1 1 1

-T. punctata Jouse' (punctate form) 1

-T. punctata Jouse' (spinose form) 1

-T. singularis Sheshukova + 1 + + + 1 2 + +

-T. temperei (Brun) Akiba et Yanagisawa + 1 1 + + + 1 1 1 + + 4 1 4 2 2 3

-T. zabelinae Jousé - - - - 2 - - + - 1 - - 4 1

T. sp. B + + + +

-Mesodyction ? sp.

-Thalassiothrix longissimaCleve et Grunow + 1

-Total number of valves counted ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀

Resting spore of Chaetoceros 5 6 4 9 4 1 8 4 10 4 12 9 9 15 3 12 10 0 6 14 6 5 4 2 6 10 14 8 3 6

D68 D70 D73 D75

第2表真山ルートの珪藻化石産出表（2）女川層・船川層

(12)

Formations Fn Minamihirasawa Formation Nishmizukuti Formation

Diatom zones NPD7Bb NPD8

Sample number (Sn-) 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 89 90 91 93 94

Original sample number (Oga-) 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 59 60 61 63 64

97277 97278 97279 97280 97281 97282 97283 97284 97285 97286 97287 97288 97289 97290 97291 97292 97293 97294 97296 97297 97298 97300 97301

Preservation P P M M P P P P P P P P P P P P P P P P P P P

Abundance R C A C C A C R R R R R R R R R R R C R R R R

Actinocyclus curvatulus Janisch - - - - 9

-A. ellipticus Grunow - - - + - - -

-A. ingens f. ingens (Rattray) Whiting et Schrader 1 1 1 - - - - - 1 - - 2 - + 1 - - - - 2 1 - 1

A. ochotensis - - - - 1

-A. octonarius Ehrenberg 1 2 2 + 2 1 1 3 2 - - - - - 1 2 - - 2 - 2 1 2

A. tenerus (Brébisson) Andrews - - - 1 - - - - - - -

-Actinoptychus senarius (Ehrenberg) Ehrenberg 1 + 2 1 - 1 - 8 3 - - 2 + 1 - 2 1 1 2 - - 2 1

A. splendens (Shadbolt) Ralfs - - - - 1 - - - - 1 -

-Aulacoseira spp. 1 2 2 - - 1 + 3 - 36 3 8 10 1 27 11 30 32 + 6 5 2 4

Azpeitia nodulifera (Schmidt) Fryxell et Sims - 1 - - - - 1 - - 5

-Cocconeis costata Gregory 1 - + 1 1 1 - - - - - 1 - - -

-C. scutellum Ehrenberg 1 1 - - -

-C. vitrea Brun + - - - - 1 - - 1 - - -

-Coscinodiscus marginatus Ehrenberg 5 4 5 6 6 6 6 4 29 37 76 64 78 47 25 46 42 6 1 2 15 10 7

C. spp. - - 3 - - - - 1 - - 5 3

Cosmiodiscus insignis Jousé 2 - 1 - 1 - - 1 - - -

-Delphineis surirella (Ehrenberg) Andrews - - + - - - - + 1 - - + - - 1 - - - - 2

-Denticulopsis dimorpha var. areolata Y. et A. - - + - - + - - -

-D. hustedtii (Simonsen et Kanaya) Simonsen - - - - 1 - - -

-D. hyalina (Schrader) Simonsen - - + - - - 1 - - -

-D. katayamae Maruyama - - - - 1 - - -

-D. praedimorpha var. praedimorpha Barron 1 - - - - 1 - - -

-D. simonsenii Yanagisawa et Akiba - + - - -

-D. vulgaris (Okuno) Yanagisawa et Akiba - + + - - - + - - + - - - + - - + - + - - -

-Diploneis smithii (Brébisson) Cleve - + 1 + - - - - 1 1 - - - - 1 1 - - 3 1

-Grammatophora spp. + + - - - + - + - - - +

-Hemidiscus cuneiformis Wallich - - - - 1 - - 1 + - - -

-Hyalodiscus obsoletus Sheshukova 6 4 + 1 - 1 1 3 3 - - 1 - - - 1 - 1 - - - -

-Koizumia tatsunokuchiensis (Koizumi) Yanagisawa - - + + - - -

-Melosira sol (Ehrenberg) Kützing - - - - 1 - - -

-Neodenticula kamtschatica (Zabelina) A. et Y. 39 36 64 61 48 63 75 23 17 - 2 + 2 - 3 5 - 2 + - - 3 4

N. koizumii Akiba et Yanagisawa - - - + - - 8 8

Nitzschia reinholdii Kanaya ex Barron et Baldauf - + - - - + - - -

-N. rolandii Schrader emend. Koizumi 1 2 + - - -

-Odontella aurita (Lyngbye) Agardh - - - - 1 - -

-Paralia sulcata (Ehrenberg) Cleve 6 1 4 2 10 5 12 8 23 10 14 11 6 7 16 13 6 8 44 - 33 26 25

Proboscia alata (Brightwell) Sundstöm 1 - - -

-P. barboi (Brun) Jordan et Priddle 6 18 4 3 5 - - 5 10 2 1 - 1 - 1 - - - 1 1 - 1 6

Rhizosolenia bergonii Peragallo - - - - 2 - 1 - - 4 - - -

-R. hebetata f. hiemalis Gran 1 - + - 1 1 1 - - - - 1 1 - +

-R. styliformis Brightwell - 4 2 - 1 - 1 - - - - 1 2

Stellarima microtrias (Ehrenberg) Hasle et Sims - - - - 1 - - - - - 1 1

Stephanopyxis dimorpha Schrader - - - - 1 1

S. spp. 3 5 1 5 5 - + 2 - 2 1 3 - - 2 2 2 - 2 - - - 3

Thalassionema nitzschioides (Grunow) H. et M. P. 15 12 4 5 2 10 - 18 7 1 - 2 + 1 8 6 3 7 40 4 33 11 18

T. nitzschioides var. parva Heiden et kolbe - - - - 1

-T. robusta Schrader - - - - - 1 - 1 - 1 - 1 + 1 + - 1 - - - +

Thalassiosira antiqua (Grunow) Cleve-Euler - + - - 1 - - 1 - - - - 1 - 2 2 - - 1 + 5

T. convexa var. aspinosa Schrader - - - - 2 - - 1 8 10 2 4 1 3 - 1

T. gravida f. fossilis Jousé - + + 2 2 - - -

-T. jacksonii Koizumi et Barron in Koizumi 1 + 1 1 1 4 - - -

-T. leptopus (Grunow) Hasle et Fryxell - - + - - -

-T. manifesta Sheshukova - - - + - - -

-T. marujamica Sheshukova 3 + - 2 2 - 1 7 - - -

-T. nidulus (Temp. et Brun) Jousé - - + - - -

-T. oestrupii (Ostenfeld) Proshkina-Labrenko + 2 2 - 2 1 - 2 - - - - 1 1 1 2 + - 2 7 4

T. punctata Jousé (spinose form) - + - + - - -

-T. temperei (Brun) Akiba et Yanagisawa - 1 - - -

-T. tertiaria Sheshukova - - - - 1 - - -

-T. trifulta Fryxell - - - 1 - - -

-T. zabelinae Jousé 1 4 - 5 4 2 1 5 2 - 1 - 1 1 1 - - -

-T. spp. 3 - + 3 6 - - - - 2 2 - - - 1 - - - - 4

Thalassiothrix longissimaCleve et Grunow + - - + - - - 1 + - - - + - - -

-Triceratium arcticum Brightwell - - - - 1 - - -

-Actinocyclus sp. (undulated) - - - - 1 - - -

-Cyclotella spp. - + 1 + - 1 - 3 - 3 - 1 - 1 1 - 1 2 - - - 2

-Mesodyction ? sp. - + - - - - 4 - - - - 2 - -

-Pliocaenicus spp. - - - - 1 - - -

-Stephanodiscus spp. - - - - 1 1 - + 2 2 1 - 1 1 - 1 -

-Total number of valves counted ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ ₁₀₀ 65 ₁₀₀ ₁₀₀ ₁₀₀ 69 ₁₀₀ 20 ₁₀₀ ₁₀₀ ₁₀₀

Resting spore of Chaetoceros 17 37 16 19 5 32 8 18 37 16 9 12 7 0 12 22 12 7 12 1 19 136 162

第

3表真山ルートの珪藻化石産出表（3）南平沢層・西水口層

Table 3 Occurrence chart of diatoms in the Shinzan stratigraphic section (3)

(13)

Formation Nishi- Onnagawa Formation kurosawa

Diatom zones NPD4Bb NPD5B NPD5C

Diatom biohorizons

Sample number (16'-) 01 02 03 04 05 06 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Original sample number (Oga-) ₁₃₃ ₁₃₄ ₁₃₅ ₁₃₆ ₁₃₇ ₁₃₈ ₁₄₀ ₁₄₁ ₁₄₂ ₁₄₃ ₁₄₄ ₁₄₅ ₁₄₆ ₁₄₇ ₁₄₈ ₁₄₉ ₁₅₀ ₁₅₁ ₁₅₂ ₁₅₃ ₁₅₄ ₁₅₅ ₁₅₆ ₁₅₇ ₁₅₈ ₁₅₉ ₁₆₀ ₁₆₁ ₁₆₂ ₁₆₃ ₁₆₄ ₁₆₅ ₁₆₆

Registration number (GSJR-) 97310 9731 1 97312 97313 97314 97315 97316 97317 97318 97319 97320 97321 97322 97323 97324 97325 97326 97327 97328 97329 97330 97331 97332 97333 97334 97335 97336 97337 97338 97339 97340 97341 97342 Preservation P P P P P P P P P M P P P P P P P P P P P P P M G G G P G M P G G Abundance R R R R R R R R R R C R R R R R R R R R R R R R A A A C A A A C C

Actinocyclus ellipticus Grunow + 1 +

-A. ingens f. ingens (Rattray) Whiting et Schrader 23 12 17 19 31 42 17 6 8 20 69 30 43 15 11 16 26 4 19 7 6 6 11 5 8 3 5 20 4 12 40 1 5

A. ingens f. nodus (Baldauf) Whiting et Schrader + 21 +

-A. octonarius Ehrenberg 1 +

-Actinoptychus senarius (Ehrenberg) Ehrenberg + 1 + 3 1 + 2 2 3 3 1 1 1 4 5 3 3 2 2 1

-Asteromphalus spp. 1

-Azpeitia endoi (Kanaya) Sims et Fryxell 1 1 2 3 4 1 2 1

-A. vetustissima (Pantocsek) Sims + + 1 1 2 + 1

-Cavitatus jouseanus (Sheshukova) Williams + + +

-C. miocenicus (Schrader) Akiba et Yanagisawa + + + + 1 + +

-Cocconeis vitrea Brun 1 1

-Coscinodiscus marginatus Ehrenberg 2 1 2 8 5 1 2 1 - 9 8 11 30 28 36 21 32 25 25 20 18 24 18 - 2 - - 1 1 2 1 - +

Crucidenticula punctata (Schrader) Akiba et Yanagisawa +

-Delphineis surirella (Ehrenberg) Andrews 1 +

-Denticulopsis crassa Yanagisawa et Akiba 1 2 1 + 1 +

-D. hyalina (Schrader) Simonsen 17 19 + 1

-D. praedimorpha var. minor Yanagisawa et Akiba + 3 5 8 2 + 1 + 1

-(Closed copula) + 7 2 2 4 5 2 1 3 4 2 4 1 3 3 4 1 +

-D. praedimorpha var. praedimorpha Barron ex Akiba 2 + + 2 2 5 2 1 1 4 1

-(Closed copula) + 1 + 1 + + 6 1 13 8 36 5 10 2 10 1 9 1

-D. simonsenii Yanagisawa et Akiba - - - - + + + 2 2 2 1 - + + 3 + 3 1 1 - + - 3 2 2 4 5 4 19 8 + 15 17

D. vulgaris (Okuno) Yanagisawa et Akiba - - - + - - + - + - - - + + 5 4 1 3 5 + 4 2

Girdle view of D. hyalina group 1 1

-S-type girdle viewof D. simonsenii group - - - - 1 - + 3 2 3 4 - - - + - 1 - 1 - 2 - - 2 + - 2 2 5 5 + 10 7

Diploneis smithii (Brébisson) Cleve 1

-Eucampia sp. A (= Hemiaulus polymorphus Grunow) 1 + 1 1 2

-Hyalodiscus obsoletus Sheshukova + 2 1 1 1 1 1 1 3 +

-Ikebea tenuis (Brun) Akiba + + 1 + 1 1 1 + 1 1 1 1 2 3

-Mediaria splendida Sheshukova + +

-M. splendida f. tenera Schrader +

-Melosira sol (Ehrenberg) Kützing 1 2

-Nitzschia heteropolica Schrader - - - + - + + - - 1 - + - - - - + - - + + + 1 + - - - - - 3

Paralia sulcata(Ehrenberg) Cleve 3 - - - 3 + 4 8 8 1 4 2 3 - 5 5 1 - 3 5 3 7 1 2 2 5 3 5 9 - 3 2 7

Proboscia alata (Brightwell) Sundstöm + 1

-P. barboi (Brun) Jordan et Priddle - - - - 3 1 + 1 3 2 4 - 2 - 5 - 19 7 23 - 8 - 4 6 6 3 6 6 - 2 - 1 2

Rhizosolenia hebetata f. hiemalis Gran - - - - 1 - - - - - 1 - - 13 - 6 - 2 1 - 3 - 2

R. miocenica Schrader 1 3

-R. styliformis Brightwell 2 3 1 + 1 2 2

-Rouxia californica Peragallo - - - + - - + - - - + +

Stellarima microtrias (Ehrenberg) Hasle et Sims 1 1 1 1 1 1 + 1 + 2 1

-Stephanogonia hanzawae Kanaya 1 1

-Stephanopyxis spp. + 2 1 + 2 2 + 1 1 1 1 3 1 2 6 1 2 2 1 1 1 3 1 4 1

-Thalassionema hirosakiensis (Kanaya) Schrader 3 10 + + 1 + 1 1 2 1 + 3 2 + 1 1

-T. cf. hirosakiensis (Kanaya) Schrader 1 5 1

-T. nitzschioides (Grunow) H. et M. Peragallo 3 8 1 - 5 3 11 8 16 6 9 5 12 4 24 4 5 4 20 9 6 5 4 6 18 65 11 2 3 5 1 12 5

Thalassiosira grunowii Akiba et Yanagisawa + + 1 2 1

-T. leptopus (Grunow) Hasle et Fryxell + 1 1

-T. cf. temperei (Brun) Akiba et Yanagisawa +

-T. yabei (Kanaya) Akiba et Yanagisawa + +

-Thalassiothrix longissimaCleve et Grunow + + 1 1 + 1 +

-Triceratium condecorum Brightwell +

-Total number of valves counted 50 50 20 50 50 50 50 50 50 50 ₁₀₀ 50 ₁₀₀ 50 ₁₀₀ 50 ₁₀₀ 50 ₁₀₀ 50 50 50 50 50 50 ₁₀₀ 50 50 50 50 50 50 50

Resting spore of Chaetoceros 8 1 1 1 6 4 17 6 3 8 8 8 23 9 18 13 17 12 45 19 41 20 30 21 10 49 38 26 5 11 4 5 1

D55 D50-52 D53

第

4表地点16’の珪藻化石産出表

Table 4 Occurrence chart of diatoms in site 16'.

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Formation Onnagawa Formation

Diatom zones NPD5D NPD6A

Sample number (17-) 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

Original sample number (Oga-) ₂₀₂ ₂₀₃ ₂₀₄ ₂₀₅ ₂₀₆ ₂₀₇ ₂₀₈ ₂₀₉ ₂₁₀ ₂₁1 ₂₁₂ ₂₁₃ ₂₁₄ ₂₁₅ ₂₁₆ ₂₁₇ ₂₁₈ ₂₁₉ ₂₂₀ ₂₂₁ ₂₂₂ ₂₂₃ ₂₂₄ ₂₂₅ ₂₂₆ ₂₂₇

97358 97359 97360 97361 97362 97363 97364 97365 97366 97367 97368 97369 97370 97371 97372 97373 97374 97375 97376 97377 97378 97379 97380 97381 97382 97383

Preservation P P P P M M P P P P M M M M M M P P P P P G G G G G

Abundance R R C R C C C C C C C C C C C C R R R R R A A A A A

Actinocyclus ingens f. planus Whiting et Schrader 1 1 1

-A. ingens f. ingens (Rattray) Whiting et Schrader 9 24 19 13 34 36 33 29 27 25 21 27 38 35 25 43 5 3 13 19 15 25 21 32 11 13

Actinoptychus senarius (Ehrenberg) Ehrenberg 2 2 4 4 2 2 + 12 1 1 3 2 2 1 1 2 1

-Aulacoseira spp. 1 1

-Azpeitia endoi (Kanaya) Sims et Fryxell 2 2 1 1 4 + 1 1 5 1 13 7 5 2 2 2

-Cavitatus jouseanus (Sheshukova) Williams +

-C. miocenicus (Schrader) Akiba et Yanagisawa + + +

-Cocconeis costata Gregory 1

-C. scutellum Ehrenberg 1 1

-Coscinodiscus marginatus Ehrenberg 63 56 15 21 5 6 14 7 5 14 4 14 2 4 8 3 12 23 15 20 4 5 3 - 2 7

Delphineis surirella (Ehrenberg) Andrews +

-Denticulopsis crassa Yanagisawa et Akiba 1

-D. dimorpha var. dimorpha (Schrader) Simonsen + +

-(Closed copula) 8 4 2 1 2 + + 2 2 + 3 +

-D. dimorpha var. areolata Yanagisawa et Akiba 2 1 1 2

-(Closed copula) 4 1 1 + 3 10 18

-D. katayamae Maruyama - - - + + + 4 1 + + 3 2 2 2 2 2 + + + 2

D. praekatayamae Yanagisawa et Akiba 1 1 + + 1 + 3 1 + + + + + 1

-D. vulgaris (Okuno) Yanagisawa et Akiba 1 + + + + + 1 1

-S-type girdle viewof D. simonsenii group +

-D-type girdle viewof D. simonsenii group 1 2 + + 2 2 2

-Diploneis bombus Ehrenberg 1

-D. smithii (Brébisson) Cleve 1 1 1 +

-Grammatophora spp. +

-Hemidiscus cuneiformis Wallich 1

-Hyalodiscus obsoletus Sheshukova - 1 2 - - - - - 1 - 2 + - + - - 2 1 2 - - 1 2 1 + 2

Paralia sulcata(Ehrenberg) Cleve 3 9 7 1 1 - 3 5 4 4 2 + 2 3 5 + 13 8 3 4 7 1 5 3 3 1

Proboscia barboi (Brun) Jordan et Priddle 9 2 - + 4 + + - - - - 1 2 1 2 1 - - - 1 7 3 12 3 29 23

Rhizosolenia hebetata f. hiemalis Gran 1 3 1

-R. miocenica Schrader 1 1

-R. styliformis Brightwell 1 1 +

-Stellarima microtrias (Ehrenberg) Hasle et Sims 2 + 1 1

-Stephanopyxis spp. 2 1 1 1 1

-Thalassionema hirosakiensis (Kanaya) Schrader 1

-T. nitzschioides (Grunow) H. et M. Peragallo 14 - - 4 2 - - + 4 4 2 2 - - 2 2 + 2 5 1 8 3 2 8 - 2

T. schraderi Akiba - - - - - 1 - - 2 + - 4 + 1 - + - - - - 1 2 - - - +

T. sp. A (pointed) + +

-Thalassiosira grunowii Akiba et Yanagisawa 2 1

-T. minutissima Oreshkina 1

-T. temperei (Brun) Akiba et Yanagisawa 1 1

-Thalassiothrix longissimaCleve et Grunow

-Total number of valves counted ₁₀₀ ₁₀₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀ ₅₀

Resting spore of Chaetoceros 12 8 4 0 3 3 2 9 0 5 5 1 2 2 4 2 6 1 9 1 5 5 3 6 2 5

第5表地点17の珪藻化石産出表

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Diatom zones NPD 5C 6A ? 6B

Sample number Togawan- 06 04 03 01

97389 97387 97386 97384

Preservation P P P M

Abundance R R PD R

Actinocyclus ingens f. ingens (Rattray) Whiting et Schrader 11 5 7 1

A. sp. A (small) - 2 -

-Actinoptychus senarius (Ehrenberg) Ehrenberg - 9 2 2

Aulacoseira spp. 3 - 2 +

Azpeitia vetustissima (Pantocsek) Sims + - -

-Cavitatus jouseanus (Sheshukova) Williams 3 - +

-C. miocenicus (Schrader) Akiba et Yanagisawa 1 - -

-Cocconeis curviritunda Brun et Temp. - + - +

Coscinodiscus marginatus Ehrenberg - 15 8 71

C. spp. - 1 5

-Delphineis surirella (Ehrenberg) Andrews - 1 - 1

Denticulopsis hyalina (Schrader) Simonsen + - -

-D. katayamae Maruyama - 2 -

-D. simonsenii Yanagisawa et Akiba 7 - -

-D. vulgaris (Okuno) Yanagisawa et Akiba 2 + -

-S-type girdle view of D. simonsenii group 8 - -

-Diploneis smithii (Brébisson) Cleve - 1 -

-Hyalodiscus obsoletus Sheshukova 1 7 1 +

Ikebea tenuis (Brun) Akiba 2 - -

-Melosira sol (Ehrenberg) Kützing - 4 - +

Nitzschia grunowii Hasle - - - +

N. heteropolica Schrader + - -

-N. pliocena (Brun) Merz - - - +

Paralia sulcata (Ehrenberg) Cleve 19 15 2 4

Proboscia barboi (Brun) Jordan et Priddle 2 32 21 17

Rhizosolenia hebetata f. hiemalis Gran 2 - -

-R. styliformis Brightwell 2 - -

-Rouxia californica Peragallo + - - +

Stellarima microtrias (Ehrenberg) Hasle et Sims - - - +

Stephanopyxis spp. + - 1

-Thalassionema hirosakiensis (Kanaya) Schrader 3 - -

-T. nitzschioides (Grunow) H. et M. Peragallo 34 6 3 3

T. schraderi Akiba - - - 1

Thalassiosira temperei (Brun) Akiba et Yanagisawa + + - +

Thalassiothrix longissima Cleve et Grunow + - - +

Total number of valves counted 100 100 52 100

Resting spore of Chaetoceros 25 31 1 9

P: poor, M: moderate, R:rare, PD:poor diatom

第6表地点20の珪藻化石産出表

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- 16 -

第

7 表地点 Tg の珪藻化石産出表

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