蝋 ii 婁 Hirokazu KATO 藷 - gsj.jp

報文

地調月報Bull.Geo1.SumJapan,vo1.30,P･71-130.1979

��㈴㌺��㈨��

亙⑭Ms⑬fM1量⑱c⑧独e亙破㎜盆t量｡苅霞虹H壇鮒舳固C臨搬醐醐盈固量s組量碗,

醐窒雪忍醐⑰乎㈹船6碗蝸,Ce斑鮒釦J認聾盈醜

��歡��

且.亙重亘t亙⑭逮幽｡t量⑱醜

Manygeo1ogistshavebeenattractedbythegeo1ogyandtectonicsinthe亙｡ssaMagnaRegionfor

manyyears(H0MMA,1931;M0RエsHITA,θ㍑1.,1957;TANA㎜,1958;SAIT0.1961.1968;TAKEsHITA,

1969,etc.).varioustypesofsedimentary,vo1canicorintmsiverocksofNeogenetoQ岬temaryAge

distributeinthisregion,and-manygeo1ogica1structures,inparticu1ar£o1dsandfau1tswhose

orientationand一缶rmsarecharacteristicdeve1opethere.

周��畤��来漱�楣��晴�獲敧楯�慶敧�慴��癡��湲散��

werenota1waysenoughtoexp1ainthestructura1andt㏄tonicdevelopmentquantitative1y.The

ana1ytica1studyoftheirstructura1developmentisexpectedtobeagoodkeybrthro㎞ng1ightonthe

geo1ogica1historyofGreentu任MovementinthisFossaM包gnaRegi㎝.

Thepurposesofthisstudyaretode丘nedeformationsinthenorthempartoftheEossaMagna

剥�潮��楮�敢�楮杭散��慮��楣��慮�潤楳��楣景�楮�楳瑯特��

ordertogetanswersofthesesubècts,somedetai1ed丘e1dsurvey,experimenta1andtheoretica1stud-y

havebeendoneasdescribedinthe£o11oweingsections.

2.G樽⑬E⑪g量｡錫亙Se重鹸搬g

Thestudiedareaisshownin亙igure1.ManystudentsofTokyoUniversityof配ucationsurveyed

thisareaasshownin亙igure1.Thestratigraphicsequenceandthecorre1ationareshowninTab1e1

慮搭㈮

Neitherthebaseroc良snorthe1owestTertiarybrmationare此mdinthearea(亙ig.2).

周敎�来��牡��癩��楴��楸景�慴楯�楮慳捥�楮杯�敲�慢��

亙｡丁遍亀uc舳㎜魍欄肪r幽純量⑬秘(Mid-d1eMiocene)iscomposedof乱ndesite1ava,tu任bre㏄ia,and-

tu脂｡eoussandstoneandsha1ewith比ssi1s,forexamp1e,Ba1anussp.,Ch1amyssp.,andsoon.The

brmationdistributeson1yinthecrestpartoftheNishikibeAntic1ine,thatis,Miyanoiri,Ho趾k両i-

捨��畤��

2.丁胞e跳§曲⑬亙脱醐就孟碗(Midd1eMi㏄ene)whichover1aytheUchimura亙｡rmationwith

con缶rmity.ismain1ycomposedofmassiveb1acksha1ewithman.ybssi1s.However,theuppermost

partoftheおrmationconsistsofmediumandcoarsegrainedsandstone,conglomerateanda1temation

ofsandstoneandmudstone.Itstype1oca1ity三stheYuRivernearBesshoSpainShiod-a-cho.The

一71一� 報　　文

地調月報BulLGeoLSurv・Japan，vo1・30，p・71－130，1979 551．243　　551．782　（521．52）

Fo聰s⑪蛋M：量⑪c㊧聡e恥暫m蠣o麗i盟騰9題s跡C膿監麗戯題互》量謝量c重，

　　　　　　　　　　　　圃題9鴇舩o　P欝e露ec重覗欝鱈，Ce聡重暫魏」麗験盆聡

Hirokazu　KATO

且．　　亙聡重『⑪《畳賜c重量⑪聡

　　Many　geologists　have　been　attracted　by　the　geology　and　tectonics　in　the　Fossa　Magna：Region　fbr

many　years（HoMMA，19311MoRlsHITA，蜘」。，19571TANAKへ，19581SAITo，1961，19681TAKEsHITA，

1969，etc．）．Various　types　ofsedimentary，volcanic　or　intrusive　rocks　ofNeogene　to　Qμatemary　Age

distribute　in　this　region，and　many　geological　structures，in　particular　fblds　and飴ults　whose

orientation　and　fbrms　are　characteristic　develope　there．

　　T｝真ough　studies　on　the　geological　history　of　this　region　have　greatly　advanced，in　recent　years，they

were　not　always　enough　to　explain　the　structural　and　tectonic　development　quantitatively．The

analytical　study　oftheir　structural　development　is　expected　to　be　a　good　key　fbr　throwing　light　on　the

geological　history　ofGreentuffMovement　in　thls　Fossa　Magna　Region．

　　The　purposes　of　this　study　are　to　de且ne　defbmations　in　the　northem　part　of　the　Fossa　Magna

Region，to　explain　the　fblding　mechanism　analytically　and　to　discuss　the　dynamic　fblding　history．In

order　to　get　answers　ofthese　subjects，some　detailed　field　survey，experimental　and　theoretical　study

have　been　done　as　described　in　the　fblloweing　sections．

鶏

多

撫蝋

きき

ii

婁

護萎

ii

　藷

議

き

2．　《｝⑱⑪且⑪9量c麗互s㊧重重量聡9

　　The　studied　area　is　shown　in　Figure1．Many　students　ofTokyo　University　ofEducation　surveyed

this　area　as　shown　in　Figure1．The　str乱tigraphic　sequence　and　the　correlation　are　shown　in　Table　l

and，2．

　　Neither　the　base　rocks　nor　the　lowest　Tertiary　fbrmation　are　fbund　in　the　area（Fig．2）．

　　The　Neogene　strata　are　divided　lit五〇10gically　into　six　fbrmations　in　ascending　order（Table1）。

　　且。丁睡Uc賊鵬纒認⑪暫脇魏量⑪聡（Middle　Miocene）iscomposedofandesite　lava，tuffbreccia，and

tufぬceous　sandstone　and　shale　with　fbssils，fbr　example，Balanus　sp。，Chlamys　sp．，and　so　on．The

fbrmation　distributes　only　in　the　crest　part　ofthe　Nishikibe　Anticline，that　is，Miyanoiri，Ho触tji－

cho　in　the　studied　area．

　　2。丁睡聡es曲⑪F⑪鯉臨量磯（Middle　Miocene）which　overlay　the　Uchimura　Formation　with

confbmity，is　mainly　composed　of　massive　black　shale　with　many　fbssils．However，the　uppermost

part　ofthe　fbrmation　consists　ofmedium　and　coarse　grained　sandstone，conglomerate　and　altemation

of　sandstone　and　mudstone．Its　type　locality　is　the　Yu　River　near　Bessho　Spa　in　Shioda－cho．The

一71

地質調査所月報

(第30巻第2号)

■グ

◎

乁�乏

束副

終.

啅�

◎

MATSU〈《O↑◎

◎

伀

�

�

�

�

SHlMlZu1970'21〈AT0196933KAV仏uCト111974'

FUKAZA～A1972'5TAKEUCH11971j6KASAト1ARA19μ;

MARU11972;81〈脈∪C卜111972191T011972'

亙ig･1I■dexn1apofthestudiedarea.

thickness･fth･缶･m･･i･･i･････…b1･･･…w･i･醐･･…;1…m-2…m･…M･･｡｡㎜｡･｡･i｡｡,

1･350㎜i･･h･m･･h･･････…fM･…m…α･･,1,000m+1･A･…w･,･00m｡･B｡｡｡h.S｡､,､｡d

350m･…Chik･m･Ri･･…hi･危㎜･･i･･i･1･…d･d㎞･･dik…f｡･･｡h｡･i･｡,｡｡包｡･｡.di｡､i｡､､｡d

and･･it･･I･･･…i･･m･･yb･･i1･,お･…mp1･,の･･肋后舳伽1,0脇肋∫｡肋肋1,ム"､6､､､加"｡､ω{､､｡d

��

3･脇A⑳蝸⑬鰯触･･m･･i･････…m…i･･…d･･h･1･m･i･1.i･･h･1.w｡｡｡｡｡｡､｡d｡･､

一72一�

地質調査所月報（第30巻第2号）

　㊥NAG　NO

　　◎

NAGANO

黛多ひ

｝

　　　　　嘔

灘灘難灘、

騨騨

　　　　　　　　　　　　　健

　　　　　　　　　　　　焦●

鑛籔灘懸

難鱗欝欝　’

U［DA　◎

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　0　　　5　　　1K納　　　　　　　　　　　　　　くくATSU〈《OTO　　　　　　　　　　　　　　　　　　　◎

　　　　　　　　　　lSH酬ZU1970，　2KATO19697　3KA陥uCHl19743　　　　　　　　　　4FU漁Z舗1972；　5TAKEUCH口971；　6陥S酬ARA19Z4；　　　　　　　　　　7納ARUI1972；　8KIKUCH口972；　91TOl1972；

　　　　　　　　　　　　　　　　　　　　　Fig．1　1ndex　nlap　of　the　studied　are乱・

thickness　ofthefbrmationis　changeableasshownin　Figure411500m－2000mnear　Matsumoto　City，

1，350m　in　the　northeast　part　ofMatsumoto　City，1，000m十in　Anazawa，500m　at　Bessho　Spa，and

350mnearChikumaR．iver．Thisfbrmationisintrudedwithdikesofporphyrite，quartz－dioriteand

andesite。1t　contains　many　fbssils，fbr　example，Z）o吻毎肋η8hα吻，0痂611郷o翻ん漉，孟ηα伽α7痂06η5ゴ5and

so　on．

　3．丁恥e　A⑪髄F翻繊髄磯comprieses　grey　massive　sandy　shale　mainly　in　the　lower　part　and　the

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　－72一

.急冒一S届｡H8o

N.bo葭

毫y◎一

り･葛､◎岡固

日HH【

.圭･.圭皇.毛塗£主､篭省違

Φ至二嘉■■

Φ奪音婁刃§毛､･蟹8曲.一.吻鰍㎜

㌧い

ξエ〇一気芝蟻Oム

○エ的的窒

署固◎』

��

♪簸漂齪

�㈱＼､･＼

燃＼

巡､

一Φを一

��○で{

■��唯蜆｡茸

｣θ^!d

苗ム凄Φε､圭◎工物刃､､.ω.吻､､一､で◎Z

あ毛碧.主･.{で､･.､.､o､､暑

ぷ竈ε.ω.吻呈馨ε暮艮･毛◎

髪�騒ZO;<ミ露◎』

妻OO

繋脚あ音碧.吻.吻茎馨三と主旨｡｡

主星◎と◎で｡ム

あ毛碧⑪{轟{･8Φ①毒

､嚢欝一一一一一寸..･㎜閉㎜.榊一鱗一一附……一搬一一一､-.-

董で§撃{ξ･言･曹亙鰯鐘

Φ宕毫看･蓋鰯蟻

Φ宕∪o◎-

毛筆童子･モ8妻麗灘

.圭｡で､｡.､で｡ε..g8..一.｡り昌≡昌

ZO巨<乏産◎』

<Z<固◎のつの

ア㎜燃㎜一糠一鐵川川川川…パ燃鐵撒

㎜㎜㎜㎜㎜…･榊一一.･一一･.舳舳榊鰯一鱗榊㎜㎜

燃.一一-棚一一一一欄1

丱28⑩圭

}中コ南6り山ζ◎o-◎>2宕吻Φで⊆<

Φ着Φで蕎貧20

#辞帖

鰯團ω》り◎産

】Z<〇一〇>

幽Zミ〈⊃吻ヒ毫

⑳虐認で蕎塞巽9証婁←

Φ蓬窒◎一g◎圭3毛<

Φ志$で§Φ号ミ

主g3塞巽9を◎差-{>δ

麗�鰯騒の》oO幽

】Z<〇一◎>

<麦撃重｢王

者&毛き;で;Φちω2◎

ε◎◎一

エムΦ◎

鰯□口

騒一､1

��

⊥り｡o�

1

2一

3一博

4一甚

6一鑛　　講

7一

8一

．％

萎………副

、………藝1一一、…… …i’

な…圭……………’

一’

芝

　　　　　　　　　ロ

　　　　　鋸・’蝋、，、｝，・1崎’

　　　　　　　　　　　欝N

1

翻DebrlsロコL◎αm

駿Obαsu骨e鵬udfl。wdep◎5i骨5

H駐」目剣YA《へA

VOLCAN國CROCKS

灘羅αMn一曾w◎pyr◎xe醗bαsd曾

麟Augi暫eqndesl骨e

囮Andesi骨icαggl・me贈e

灘Tw・pyr・xene副esi曾e

〈〈隠SU〈A図N曜

VOLCANICROCKS

匝互］GlαSSyα齢desl曾e

騨翻Andesi曾icv・1㈱百c一曾uffbre蜘

鰍　　鶴卵

欝TWo　pyr◎xe睨eα筋desl曾e

ii…ii………肇…甕毒華叢…妻妻轟

一萎藝…萎嚢一一藷箋萎垂萎嚢肇1

　　一　　　　＿　　＿…聲…≡…轄一　　　　　　　　　　〇

　　　　　　　ロ　　ロ　　　　　　　よ　　　　　　ヤ　藝華．　…垂…蓼、箋一．垂…　　ノ藤、凋笏　　一護…、『甕華…蓼　ノ　灘　　　一　　　　　　　　　　一　　／ノ珍

1羅嚢嚢藝．挺．霧　　　禧…藝嚢i…i…i……嚢，

　　嵯…i………i嚢…i…………i………／　　諺……iiii…i…華……………垂…i…………藝

　　……………萎………………………………

　　羅葦…i……i…華善一　

　　　　　　　　　～

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　一2

　　　　　　　　　　　　　　　　　　　　　　．一

δ《《lN距

FOR《《A柵ON購魏C◎ngl◎・αnd曾孤s・

KO醐激㎜S。s．，c◎ng・趨d5．α脆dα1骨・

Akαsh藷

　　一肇………華一笙…箋ii…i…………蘂塁罰

……差……………i．

セ

SuSOBANAFOR〈《A圃ON

ヤ

離翻V・k醜輔brecciα　　　ゆカセ　羅翻Bαsicqndesi曾e

薩翻pl◎gi◎rhy。靴1αvαα脆d賭

陸藝IShlgec◎αlbe㈱gme齢ber　　　　　　　bδdαlrα曾uff

騰鰯Sqs楠繍ss盲ve5・5・me噸

OGA陥FOR《AA贋ON

醗翻δubαy　mαsslve乳s・member

猛Agerδs澗dsh・d臨e齢ber懸N・d◎lrαs・s・◎ndshq睡・㈱be『

玉一膿器骨α腕d　yshαle

蝶慧羅離壷恋1　fチb『ec㈱f繍

AOKl

鷲舗魏oFO騰越躍lo騨

垂…≡＝‘

華藷一簿Ψ甲　　　　O

　　＿7＝…｝．　……………孝茅

一　聾権　｝駄 A◎k

舞　　一　……≡……一髪…………葦…一一

ソ ‘＝r＝＝＝＝多

ア

讐O o

≦………≡………

畢一…i…… P9

琶……藝P 一詳論＿………i

一

≡垂…葦一

・嚢 P

1 …奎一曇

0 5 10K〈《

一6

　7

囚Ob㈱骨eαndesl曾e

［二亘］A筋d蝋bα輔5hee骨

E亘］Ki骨αy㈱dαcl曾e

回P◎rphyrl曾e

匿囲Qu醜dl◎ri曾e

Fig。2　Geological　map．

Fo1dsofMiocene亙｡r㎜ationsin亘igashi-Chiku皿aDistrict,NaganoPrefecture,Centra1Japan(H.KAT0)

��

Age��(獅)C◎1Umn◎rSed;◎n��し1冊◎f◎des

�◎∪･･望瀦��■嚢鱗糞■■��◎ndeSi甘el◎y◎b◎S曲｡

��◎1◎榊e胸骨e

��K◎㎜〃��

��'��S◎nS甘◎neC◎ng◎mer◎甘e◎n耐'

��◎�d��一■一一■■■■一一1IlI11■11��

��饒�I1■1■■■■■一十一1-1一一一1一■一1-1-1-1一船'Ii･､州;･1･､◎鱗'燃ξ.◎､･;三く脳榊'��V◎1C◎饒ko菅∪晋fb干eCd◎

��c�虐��weldedfuff�

��◎ε■◎』��◎ndeS帖1◎V◎

��◎0�ε��

�岨�吻u一�峯�ひ灘灘��{91◎{y◎榊Ci◎･･

�z�コ��

��ω�2�,睦里.,一一一.一■��◎nd池肝

�山��

�o��1一一一一一■■I■一･一'一一■��胴doiroTUff�～併◎Ce0晩S◎ndS甘◎鵬

�◎��お��一一一1-i■i一��

��Φ一〇①ε�◎.;''毛毛手一��

�■��

�毫�⊆��◎';………………��

��王Φωミ�1＼嗣一11一一.一一��m雛織雛繊､

山��■o��

��◎杜��一一i'一.一1一画｡何画'｣Lω■同Iも邑��

�影�妻��一.･一一一■■■一一一.一一一I��

�uJ�◎��

�工��一一`･■1I111一一一一一一一Iiìi1一■i..･■■11-1��m◎ssives◎nd針◎鴫◎nd

�｣�①◎◎�■;』･iΦ当』�◎…≡一≡三三三三…��

�⊃��工E旨ωωミ�◎^･･}^��;8雛瞭eW帖

Z��○産量ξ事��

一■■一■一一一●'一■==::===ニニ■��d甘em◎冊◎n◎fShde◎nd

��一一I一一■一一'I一■一I･'��S◎ndSf◎鵬

山��c��

��◎●o�◎��

��杜��

��◎�◎��

��･一εよ』�oo一一･･一……一一･1i一●一'■一��燗dy･hd･

�山��

�Z��一■一一i･一■`■･��

��◎◎�F��

O�山��<』��閑SSiVe5◎0dS甘◎舵醐d

��

�◎��HorojiCo･g.Ki山C･･g.�c◎ngl◎me閑苛e

�凹��

�二…��◎肘em◎苛i◎n◎fS◎ndS甘◎鵬

O��◎ndshde

��ζ��

��◎�◎��

囚��◎ξよ◎ωεω』�◎��bl◎改Sh◎le

�幽��岬��

��

�一��

�o��Φ0��

��国M■��

��

z�■��

�:……��■■一一��

��c9.9��一一■△�云'��

��^△i一■一一一`一.��◎ndes肘e

��○杜εo･一εJ=』�一一･一一一一■1��甘)粁bre㏄b

��･一一一一一一●1��他肝◎Ce◎USS◎nd針◎鴫◎舳d

��U◎⊃』��==j一一==:=二一一i一一`■1��Shde

aItemationofsandstoneandsandysha1eintheupperpart.賄rticu1ar1y,thebasa1partofthis五〇rma-

瑩潮�癥�潭��潦�湧�浥牡�慮�慮�瑯��異��楳�浥��牡�

Member,andthe1oweroneisnamedtheKidoMember.五nthea1tematingsedim㎝taryrocks,minor

structures,suchasminor刷ds,minorfau1tsandboundinsare£ound.Itisverydi鎚｡u1ttocorre1atethe

membersoftheAokiEormationeachother,becausethe1itho1ogyofthat缶rmationischangeab1ein

thehorizonta1dir㏄tionasshowninFigure3and亙igure5.Thisおrmationbearssomefossi1sandthey

arereported-byTANA蛆(1962).Thecong1omeratecomprisesmain1ypebb1etocobb1e-sizedgrave1s

ofchertandhardsandstoneofPa1aeozoic,andesitic-basa1ticbre㏄iabrought旺｡mtheUchimura

FormationasreportedbyYAMAGIsHI功α1.(1963)andSAITδand五IJIMA(1972)on1yinUedaCity,

一73一�

Folds　ofMiocene　Fom夏ations　in　Higashi－Chikuma　District，Nagano　Prefecture，Central　Japan（H。KATo）

Table　l．

Age （m） Colu職αrSedion L百曾h◎fαcies

QUAT．膝iyq鵬αv◎k．

箋難蓑 α『1desi骨e　lαVC冒　bαSα1骨　　　　　　　　　　　’α　1◎merα骨e

囚z囲りO回≦駈段⊃

K◎mlji

　　r　6

Sα騎　S曾◎ne　C◎ng　omerα骨eα　　nα曾。

o儘　。

◎ε一Ω』◎oの園」，の

藍盤

十〇〇α

＝1二1＝1＝ロニロ＝1＝1＝尊＝

＿1＿㌧」」」1＿1－1－1一vokα髄百c一曾u督brecciqα醜desl骨e　Iαvα

plαgi・rhy◎齢ic　lqvα

　αnd曾u膏

も。釜挙£

難懇　　’憩罎　鵬・

躍既暫．馬

　おΦ』

oE三Φのミ

oo卜

甲；＝二－＝＿一

奮面αce◎US5αれds曾one

m望畿謂d縮も融．一　　一　　一　　曽　　一　　一　　　　一　　一　　一

■＝＝＝＝＝乙＝．＝＝．

．一一＿‘＿匙菩＿

　口　『　一『　一　噂　r　認

　●罧

o＝＝二’』」『』r＝＝＝

　　0　0　0　0’一◎＿卿＿鰐㌧叱更

一　　曽　　一　『　　一　　一　一　　一

タo

9ζ』P・一Φ差£窮8≦

ooつ

一　一　一一　噂　戸　胃　　一

mα551ve　Sα騎ds骨◎ne　αnd

l9駿思謙ewl母h『

噂ごr－＝＝二一＝」＝二

σ）◎

0。…Ii…一‘i…曼…膏

：：：＝二＝＝’二＝＝

瀞最i芋聾q一　一　一　r　噂　層　r　幡r　r　層　層

welded奪uff

BδdqirαTuff

Hqrqjic。ng．Kid。C。ng．

義…鯨＝葦1垂

一晶＝＝，乳顎一ロ曙需

囚z協uO四：…i囚一ΩΩ，国：……

　　盤　　o　　’軍

　　o』量o　◎＜脇

ooの四

一”　　響　　，　　　　　o　　一　． α1曾er崩q曾i◎晩◎f　shαle　α『ヤd

　　5αndsbne

sα舗dyshαle

灘ssivesα“d5骨◎隔eα醜dCO醜gl◎merq骨e

…i………：一＿一…一

≡………≡≡三養

騨　●椰一　一　一　一　曹　一

o　一　甲　●≡≡…≡………　　　ロ　ロ　　■　　一一『一一　隔r　輔　■　臼　r辱

　　艦　　o　　罵◎

　　oよ3套Φ　o虚自　由』

ooり四

＝二胴『二二7‘＝二曹

α1曾ernα舗◎睨　◎f　Sdnds骨◎ne

　α醜d　shde

blαck　shde

　　藍o　◎』　　〇四

，　軸甕…σ　　濫罎郵奎

αndesl曾e勧督brecclα曾u碍αceous　sαnds骨o購e　αrld

shde

△△

△　　△一一一一一一』一■

荘邑……≡≡

＝饗r一，＝ξ二：二一　一　　一　　一　　一　一　　一　層

騨　　　憎　　　一　　　一　　一　　　騨　　一

altemation　ofsandstone　and　sandy　shale　in　the　upper　part。Particularly，the　basal　part　ofthis　fbrma－

tionhave　two　members　composed　ofconglomerate　and　sandstonel　the　upper　one　is　named　the　Earaji

Member，and　the　lower　one　is　named　t五e　Kido　Member．In　the　altemating　sedimentary　rocks，minor

structures，such　as　minor　fblds，minor飯ults　and　boundins　arefbund．Itisverydimcult　to　correlatethe

members　ofthe　Aoki　Formation　each　other，because　the　lithology　ofthat　fbrmation　is　changeable　in

t五e　horizontal　direction　as　shown　in　Figure3and　Figure5．This　fbrmation　bears　some　fbssils　and　they

are　reported　by　TANAKA（1962）。The　conglomerate　comprises　mainly　pebble　to　cobble．sized　gravels

of　chert　and　hard　sandstone　of　Palaeozoic，andesitic．basaltic　breccia　brought　fピom　the　Uchimura

Formation　as　reported　by　YAMAGlsHI6緬乙（1963）and　SAIT6and　IIJIMA（1972）only　in　Ueda　City，

一73一

地質調査所月報(第30巻第2号)

��

��鴉Si£甜｢��OmiRiver�SOUfem◎0��

��fM昨1i'iri��SA仏1��nOr帖emC1r��

��illoe��0fMOfUmO��Nog･◎Oi1ield�湘葛､��Hig◎shki

��卓��浯��

�GEO山OG■C舳G一��FHONMA�.KO蝋SH�A.^ÔRlSHl��^^.F∪仏ZA��医.TANAKA��

��TAe庁｡l.��ト1.SEKl��H.FU｣lMO��

AGE��H.1SOMl��A��e廿｡l.��S.MARUl��H.KATO

�乁��

』��

Φ'■』�HOしO一��

潯��

⊇仁��

OI�P旧Sτ��

�一ENE�T◎γon◎Sf◎e��

��O･･S…m･_ZUSfoe一･･Slgoro-0-Umlf◎��Shigρ��Hiji･.･moA

��HijiriyomoA��Hi.ir.◎moA�oml��

��G.�K.miji｢;��

山�山��K◎mi'i･F�SU50�omUril.��SU50�er

�坐Z��'■一��KomijiF�δsδTU�bono��

��漉��嬉��呵晦��潭��

��∪pPer��a��bono�

��⊃��r

�u｣��

�山�○兆距��ε��ShigeE��Shiger�◎』��■��⊃�Φ��

�oo一��』��

��£��ShigeF･��Shigeヒ�◎.�∪pPer�0�仁Φ0>'■�山�

��O��』��ShigeF.

�o-O��……��O��WOdOnOyO�⊆��O�'一ω旨でo⊆ε9�◎�

Z��Oω��■■�Soshikiri�■一�moE�00モE��≧�

�一��E��ε��■■��o�Soshiki一

�⊃ミ��①�◎Wer�SoshikiriF�SoshikiriF�O�F.�O��妻◎�◎Wer�∈��①�

��伉物�

��O��一��

��⊃��

��◎��Kodo〔hino�ζ��

��o�Akomo一��'r;F�◎��

��｣��

山��o��'二��

��⊆��o��UpPe『

��◎�UpPer�Akomo廿sUF�AkomclfsUF�∫�fSUF��k6zowo[�ε�∪pPe『�o��.仁�

�u｣U｣��'5��◎��α��』◎��⊃�∪pPer�◎�

��o��<��⊃��0』��■=昌�

��.ε�1≡��◎』�H050doE�L��

��漉��

�一Z�.一Φユ①0◎��L��■■��

��』��E�

��｣=�◎��O��』0�middle

O��呪�L��HOridOirOE�.δ��

�ou｣�<一ω�⊃��⊆��∫��ui�

��ユ��王��

�oU��◎�∫�OWer��∫�Kifoyomor�り�◎Wer�◎��

��工�◎��◎��o��

��刀��<�◎Wer�∫�0Wer■一一一一

�一〇��<��<�Hokubo一�◎��0�

��摯

O��》��embr

�ξ一�◎Φ{oω◎��0��一■.��

��Bessho��呪u二�UpPer�0��

�≦��工ω��■=⊃89ぷO�Anclzo一��

��TozowoF.��一一一一一��

��F◎rmOfiOn��}��o��woF.��Bessho后

��⑭'一òω��Φ��o<仁�0Wer��

��固��

山��Ko･iγoho･o��甘∪ffoce��

��◎■��d�F.��d�0uSrn��

�匝山�o�コ��UpPe｢��reen��∪chimUio一

�u｣Z�;Φ.…9�◎��

��』�9δ…モ��･ok･旧f菊eF.��O��

��o』��』�pro.r.��

�≧山��o��コ��

��■=I■■∪ω��'一ε��コ��

�o��E�ShiokUroF��ε��

Z�OO�⊃�.⊆�U』⊃◎u■�1ower��■=��王��

��工閉��∪�bUkor.��U��

��⊃��⊃��⊃��

�一一■一��

�ミ�OriyOSfc1e�工�○凧◎rlγ◎F◎rmoflon��

quartz-dioriteanddioritedistributedinUchimuraregion,andb1acksha1ebre㏄ia(1O→0cminsize)

brought血omtheBessho亙ormationinthe1owerpartofthe此rmationasshowpin亙igure12.Thetype

1oca1ityofthe砧rmationis1ocateda1ongtheroadcut丘omKidoinAokiVi11agetoShunaraPass.The

1argestthickness(1,300m)is£omdinthewest1imboftheKom軸Sync1ine,andbecomesthimer

towardtheeast.Theremarkab1echangeinthethicたnessisfoundattheMatsumoto-NaganoLine.

TheAoヒiFormationover1iestheBessho亙ormationconformab1yasawho1e.

4.丁血eOg盆w冠亙鮒触銚五⑩秘inthewestemareaoftheSaigawaCrushedZoneismuchdi冊erentin

��楴�晡捩��潭�慴楮瑢�慳��慯晴�卡�慷��獨��

周慴楳��睥��楴楳摩癩�摩�潴��楲慍��爨��慴楯湯晳慮�獨�攀

慮�慮�瑯��〰浩��捫��来��敲��瑩潮潦��潮��

�〰ね楮�楣��猩��敏畢��慍��爨��慮�瑯��整��ね楮�楣��猩

楮慳捥�楮杯�敲��敲数��慵��楮��潦��条睡�畳��

Zone,theOgawa亙ormationisdividedintotwomembers,thatis,theSashikiriMemberinthe1ower

慮��敍��物��異�爬�獰散瑩癥��楳�楢畴��潮杏浩剩癥�

TheSashikiriMemberiscomposedof1ightgrey-1ightb1ue,massive,coarseto丘ne-grainedsandstone

一74一�


Table2．

GEO幽OGIC　AGE

FOSSAハAAG－

NA

誹Si龍僧「 OmiRiver SOU督em◎Of〈へtHi’iri

SAKAliIlqe

nor曾hemαrof〈《α勧mo

NqgnoOiI　ield 》朧e Higqshi肖ci

　moAreqF。HON納ALkOBA漁SH

　HISO《へ1A．〈へORISHlTAe酔ql

〈〈．FUkAZA　A

K．τANAKA　HSEKI

H。FUJl〈へO　　e曾ql． S．納ARUl H．KATO

1931 1950 1957 1971 1966 1946 1972 1977』o申r』．

oo＝》⊆

σ巳

HOLO－CENE

HijiriyαmqA Hi●iriqmqASusobqnq

P旧S不一　ENE

ToyonoSfαe

幽z国oO囚z

O］一Z－J　］

Ω一∪

SαrumoruS曾αeSigqrq－

mi量q

Shigq

rαm8G．

K。mijiF｝

HijiriqmqA

　田αZ　田一〇一∪ζLO　一⊃≦

σ誌呂三

〇の

⊃o』o．…i‘u⇒潔o＝

も⊆£ii

i8

uppe「KomijiE

Komi。i・蕪

δSδTu

KqmUr1聾。Ω．

⊃90。唇O

NqkqgomiEerSuso

bqnqKosoTuffGr r

ShigeEShigeF・

o’毒O

ShigeF． ShigeE ・uppe「］oきo①O

ShigeF．

bwer Sα5hikiriE

Sqshikiri

F．

IwqdonOyq

mq　E

1◎ζOo薯E葬〇一

Iower

α，90．　一∈O

　Φ　盧Φ　0．≧覧

3でo　⊆∈9

Sqshiki－

riF．SαshikiriE納orukiE

　］L』

一Z

Ou』

oり

一〇≦一

　≦

o剛Φ国σ》

Oo＜巾　の

⊆o’署o∈ちLO　－潔◎＜

uppe「 Akqmα甘suE Akαmα暫suEΩ．

⊃20還o＜

Kodqchino

irI　F．‘o。；o∈δ告。ヒoζu　一よりoでoy

uppe「ユ⊇90還o＜

upper．‘0

’宰o∈』o

Lo嘲誕0＜

uppe『0－◎＜

Akqmα一

曾suE lkezqwqE

HosodqFmiddle

lower

HoridqiroE

iowerKi仕qyqmqEbwer

lower一　　一　　一　　一　　圃

KidoembrHqkubqE

oΦ看σ》

8呈

皿の

BesshoFormα奮ion

0£ののΦo自

TαzqwqF．

19　

一の

u」

o　o＜ ⊆

・upper一　　一　　一　　一　　一

Iower

．2っ鴇9

おO

Anqzq－

wqF．BesshoE

緩　」1

田Z≧」1　り00一　　騙

　≦

薯Φ

鐸当の

uppe「 02⊃E孟り⊃

KqriyqhqrqF．

09⊃Eヱり⊃

青uffαce

OUsm UchimurqEInqkurq↑δ◎eF．

reehpro．r。

Ω．

コ20．9看

o⊆お．9∈も

一Eり＝）

bwerShiokurqE

1⊃

』oL lbukq　F，

0「lyα

S袖eり航oriyqFormqfion

qu＆rtz－diorite　and　diorite　distributed　in　Uchimura　region，and　blackshale　breccia（10－40cm　in　size）

broughtffom　theBessho　Formation　in　thelowerpartofthefbrmation　as　show亭in　Figure12．The　type

locality　ofthe　fbrmation　is　located　along　theroadcutf｝om　Kido　inAoki　V皿age　to　Shunara　Pass。The

largest　thickness（1，300m）is　fbund　in　the　west　limb　of　the　Kom弓i　Syncline，and　becomes　thimer

toward　the　east．The　remarkable　change　in　the　thickness　isfbundattheMatsumoto－Nagano：Line。

The　Aoki　Formation　overlies　the　Bessho　Formation　confbrmably　as　a　whole。

　4．丁恥e　Ogaw盆恥朧瞼重量磯in　the　westem　areaofthe　Saigawa　Crushed　Zone　is　much　differentin

the　lithofacies丘om　that　in　the　eastem　area　ofthe　Saigawa　Crushed　Zone．

　That　is，in　the　westem　area　it　is　divided　into　the　Nodaira　Member（the　altemation　ofsandy　shale

andsandstone，700minthickness），theAgeroMember（thealtemationofsandstoneandsandyshale，

1，000minthickness），and　the　Oubayama　Member（massivesandstone，morethan50minthickness）

in　ascending　order．These　are　reported　by　the　author　in1970Jn　the　east　of　the　Saigawa　Crushed

Zone，the　Ogawa　Formation　is　dividedintotwomembers，thatis，theSashikiriMemberinthelower

and　the　Shige　Member　in　the　upper，respectively．They　are　typically　distributed　along　Omi　River．

The　Sashikiri　Member　is　composed　of　light　grey－1igkt　blue，massive，coarse　to　fine－grained　sandstone

一74一

Fo1dsofMioceneFormationsinH1igashi-Chiku皿乱District,NaganoPre胎｡ture,Centra1J包pan(H.KAT0)

㈳��

�

◎

暮;

㌣

�

』o

潅

<δ

競

艇

910王112131415161718

口

＼

＼

＼

＼

■o

＼

�

＼

＼

＼

＼

一･刮.

＼

■

'七

＼

一クζク=;==:=ニニｰ一一一二響...

タφφφヂ'＼灘

一憂＼

…

}＼/薫

一

�

〰

E竈

｡U

.ら冒

と9

一一一千

ユ

ニ圏

住

黎｡

潅

　

�〰�

○日b日(昌d㎜1霞層9圏魑i目j囮1国1圃m麗鰯｡翻

1.SaiRiver-Tsukudami,2.KanakumaRiver-OmiRiver,3.Ikezawaroute,4.Amadamute,5.亘akubaroute,

6･◎guchi醐w邑route,7･Nag副iw邑,8･OmiRiver,9･Katsufa-Ma㏄hi,10･Bessho-Nakazato,11.Yagoshi,12.

M1割tsutome,13.Hanagaw肌aPass,14.KazakoshiPass,15.Kajiura-0mi,16.Mt.Azumaya,17.ShmaraPas冒,

18.An朋awamute.

��汳��楮��楴��慮�獨�攬�獨��瑩潮潦��潮��獨�攬昮

sha1erichaltem副tion,g.sandstoneri止a1temation,h.med三umg閉ined船ndstone,i.coarsegrained船ndstone,

j･verycoarsegraimdsandstone,k･舶ndstoneandcomglomerate,1.cong1ome閉te,m.andesite(oftheUchimura

Formation),n.rhyo1itictu旺andlava,o.副ndesite(oftheH軸riVo1canicRocks).

亙ig.3Co1um㎜ersections.

一75一�

Folds　ofMiocene　FomLations　in　Higashi－Chikuma　District，Nagano　Pre琵ctureシCentral　J＆pan（H．KATo）

12345678910箸11213唱415

16 17 艦8

　6　◎

離継

麟o註，鼻

　　難　　震

鰯飽

ノ　　ロ　　，o

　　F　　o　　一

　　　　　“グー　　　ク〃”

i纏

…曇／講

　一Σ1、

～＼

　　＼

　　＼　　　ゆ　　　叫　　　　　ロ　　　　L　　　一　　　　　覧　　　　■　　』　　一

　　　　　　　　の　　　　　　　　も　　　　　　　Oo　　　　　　　E匡　　　　　　　σu　　　　　　　，き置　　　　　　　＝≒8　　　　　　　王ダ

ー一一十　　　　　　　28　　　　　　　．8毛

　　　　　　　9§　　　　　　　⇒o

　　　のL

／曼

　“　o

湿oo∈＜b

　」

一一一一一藷一．

／騒／／

／／／

／

　⊆Oo£零認oΦEロδ　L

llOOm

q日b日c目d皿e塵f國9圃h團i國j圖k圃1團m臨n團o國

σ信も．9Eち

モ§

⊃£ 1．Sai　River－Tsukudami，2。Kanakuma　River－Omi　River，3，Ikezawa　route，4。Amada　route，5。Rakuba　route，

6．Oguchizawa　route，7・Nagaiwa，8・Omi　River，9。Katsuね一Macchi，10・Bessho－Nakazato，11・Yagoshi，12．

Matsutome，13，Hanagawara　Pass，14．Kazakoshi　Pass，15。Kajiura－Omi，16。Mt，Azumaya，豆7．Shunara　Pass，

18．Anazawa　route．

a．coal　seam，b。coa豆seam（intermittenly〉，c。sandy　shale，d。shale、e．altemation　of　sandstone　and　shale，f．

shale　rich　altemation，g．sandstone　rich　alternation，h．medium　grained　sandstone，i．coarse　grained　sandstone，

」．very　coarse　grained　sandstone，k．sandstone　and　comglomerate，L　conglomerate，m。andesite（ofthe　Uchimura

Formation），n．rhyolitic　tu仔and　lava，o。andesite（of　the　H葡iri　Volcanic　Rocks）。

　　　　　　　　　　　　　　　　　　Fig．3　　Colunuユer　sections，

一75一


　

�

異

呈豆る

危を

4K州

……

�

�

椀

一

■

�

�

･

�

�

o9σZ

◎{3oo

､

､

､

�

､

一

一

�

呪ωσ｣山工ω…Φ`ヒ｡(く

,§亡～～£

0{青さ}◎工

○妻｡Noにく

島

��

醐g.4Thethic㎞essof此eBessho亙｡r㎜ation.

A)showsnatura1thic虹1essoftheBesshoFormation.

B)shows飲aggerated凸icknessoftheBesshoFormation

�

�

､､､一凄

､

､､�


o．旨

傷

蔓

N

（A）

4K爪

v」一協乙’6二

　　〇　　ε

　　亙

　　も

　

o＞

oきσ

No仁

《

o‘り

，

謡つ

い◎＝

嘩

の切

o色

，

湿コ

｝o＝

の馴り

σ店

‘の

●6

εロ

菱

o£の切Φ

o陰

oδ　δ

Z　　　　1　」　　ノ　　　　　　　　　　ヤ　ー　　　　　　　　　　　　　、、／

（B）

1K《へ

1K1》も

1Kんへ

、

　　Fig．4　The　thic㎞ess　ofthe　Bessho　Formation。

（A）shows　natural　thic㎞ess　ofthe　Bessho　Formation．

（B）shows　exaggerated　thickness　ofthe　Bessho　Formation．

一76一

爵プ

多

.薄

口

謹

≡………姜………≡≡

一隻姜姜姜≡姜

…ヨS･･d1･h･1･

髭

'養§…姜

図S鵠鱗､､

嚢嚢A撫撫窒

･0･dγ5hd･

一美…姜……1…………

◎A◎ki

一毫……姜…嚢

''嚢萎1萎1葬

蓬

〆

伀

'≡≡≡豊

葬

10舳

適

�

Fig･5

The1itho£aciesコmapoftheAoki亙｡r㎜ation.�

N

Z菱’嚢

一藝嚢轟劉　　　　　　＝　63

……　一欝

曽驚

㌢≦無・、繕

蕊萱

塵iヨSαndyshqle

　　　　　　　　　　　　一　　　　　　　　　　　　一輩…

一　　　F　一　　　　　　　　　　　一，

　　　一　　　　　　　…≡…接　　　　　　　一　　　　　藷一　　　　　　一婆圭一

匿iコs2聯驕，．

騒　　　　　A匪†ernα量ion　of

　　　　　　sqnds曹one＆　　　　　　sαndyshde

≡…一一o　Aoki

1　　．……………………i－i………i華覇

　　　　　ロ　　　ロ　

藝彗薄一一一甲

一

一騨

一一一騨　　　F

一

F一

胴

一8

一

一

礁

0 5 10K猷

Fig。5　The　litho魚cies　map　ofthe　Aoki　Formation。

亙｡1dsofMioceneFor㎜ationsinHigashi-Chiku如aDistrict,NaganoPre胎｡ture,Centra1Japan(H.KAT0)

andcong1omerate.Coa1seams,thinmudstoneandsevera11ayersof05物価bearingsandstoneare

interca1atedinthemidd1eanduppermostpartsoftheおrmation.Cong1omeratecompriesnoton1y

chertand-sandstonegrave1sof疋re-TertiarybutGreentu任｡nesofTertiary.Thethicknessofthis

此rmationare120mnearSanse巧i,520matSashikiri,400matKamibori,andatOgawa-Koniuma,

㌵ね��潤��慮�ね慴��牡��敍��物獣潭灯�摯�慳�癥

�歯�浥摩畭杲��杲��慮�瑯��潮朱潭敲慴��湧�浥�楣��潮�

Sandymudstone,thina1temationofs夙ndstoneandsandysha1eandcoa1seamsare&equent1yinter-

ca1ete(1inthismember』tbecomestu舐aceoustowardtheupperpart.Manyripp1emar良s.1aminations

慮��景��獣慮�景�摩��潮��敲献周��来��敲楳楮�用��楴�慮�

vo1c凱nicrocks(porphyrite(1ikes,basa1tsheetandsoon)intheareaoftheeastoftheMatsumoto-

NaganoLine(Eigs.2叩d6).TheB6dairaTu任isinterca1atedintheuppermostpartoftheShige

MemberandisdistributedintermittenlyatthesouthemiootofMt.H箏iri.Thetu任iswhiteinco1or

慮��杲��畭楣敧牡楮��牢潮慣�畳��敲慮�敢��楣��晴��

tu旺memberranges缶｡m1Omto30m.Itbearsfossi1日｡faca11ed“B6dairaF1ora"andsomemo11uscan

fossi1sin舟eshwater(SAIT6andIlJIMA,1972).

ThethicknessoftheShigeMemberis490matTsukudami,620mintheareaa1㎝gOmiRiver.570

matthecrestareaofNomaAntic1ine,400matShunaraPass,250matIchinokawa包ndOnodaand-

1essthan1OOmtothee包stofOnoda..

5.醐eS鵬曲鋤a亙破㎜銚量⑧触(upperMiocene)ismain1ycomposedofrhyo1itic1ava,tu任and

千

}二155111

騒蟹･｡･1的舳･･1･･

1籔･｡･舳･

NDES1.lC呂ASA工丁

㌰〴〰�

�

Fig.6Bas釦ticandesitesheetsintheOgawaFomユa丘｡n.

一77一�

Folds　ofMiocene　Formations　in　Higashi－Chikuma　District，Nagano　Pre琵cture，σentral　Japan（H。KATo）

and　conglomerate．Coal　seams，thin　mudstone　and　several　layers　of　O5舵α一bea血g　sandstone　are

intercalated　in　the　middle　and　upPermost　parts　of　the　fbrmation．Conglomerate　compries　not　only

chert　and　sandstone　gravels　of　Pre－Tertiary　but　Greentuff　ones　of　Tertiary．The　t五ickness　of　this

fbrmationare120mnearSanse葡i，520matSashikiri，400matKamibori，andatOgawa－Koniuma，

350m　near　Onoda　and　less　than100m　at　Tokura．The　Shige　Member　is　composed　of　massive

arkose　medium　grained　and　coarse　grained　sandstone，conglomerate　and　conglometric　sandstone．

　　Sandy　mudstone，thin　altemation　ofsandstone翫nd　sandy　shale　and　coal　seams　are　fピequently　inter－

caletedinthismembeL　Itbecomestu伍ceoustowardtheupperpart．Manyripplemarks，laminations

and　plant　fbssils　can　be　fbund　in　these　sandstone　layers，The　Shige　Member　is　intruded　with　many

volcanic　rocks（porphyrite　dikes，basalt　sheet　andso　on）in　the　area　ofthe　e＆st　ofthe　Matsumoto－

Nagano：Line（Figs・2叩d6）・The　B6daira　Tuff　is　intercalated　in　the　uppermost　part　ofthe　Shige

Member　and　is　distributed　intermittenly　at　the　southem　fbot　ofMt。H弓iri．The　tuffis　white　in　color

and　contains　quartz　grains，pumice　grains，carbonaceous　matter　and　pebbles。The　thickness　of　this

tuffmemberrangesf士om　lO　mto30m。It　bears　fbssil　Hofa　called“B6dairaFlora，’andsomemolluscan

fbssils　in丘esh　water（SAIT6and　IIJIMA，1972）．

　　ThethicknessoftheShigeMemberis490matTsukudami，620mintheareaalongOmiRiver，570

matthecrestareaofNomaAnticline，400matShunaraPass，250matlchinokawaandOnodaandless　than100m　to　the　east　of　Onoda．

　　5．恥e　S盟s曲蹴a恥ぜ朧麟磯（upper　Miocene）is　mainly　composed　of　rhyolitic　lava，tu任and

ま

雛

1，撫

1鎌注難

i懸騨繍縣　　　糞

騰l　ll　覇　　　編　　　　　　　　熱

　　　　糞　　　　　　i懸　　　　　　　　ζ

篤

霞鰹

　　　　　　蟻撚

　　　　、．溝囎i饗

装

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　．離ダ

▽　　、譲雛慧麟騨　　講　　　　　　　　総鱗轡騨　　　　　謙騰　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　麟灘

　　　　　　．　…4　＿編覇翻鰯麟　　灘　難灘

　　　　　’瀬i講　　灘　講　辮，、

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1漏

　　　　8』漆　　　　　1　　　　　蓑…　塑　　　　磁灘、　鞠藩／　醗謙，，轟繍、1

鱗雛雛・・　1　01002003・・

誌潔1「壽騰羅A・KIF・R猷ATl・N

襲翻P。RPHYRlτE

睡雛ANDESτICBASAしT

Fig。6　Basaltic　andesite　sheets　in　the　Ogawa　Formation。

一77一

400　　50　　　　　　m


andesite1ava,TothesouthofHOiriHeightsandaround-Mt,Kamur胴,thisformationisdividedinto

threemembers.The1owestmembermain1ycomprisesofp1ag三〇一rhyoIitictu任and1avaandpart1y

�捩��癡��牧��牴�牡楮�晷�捨摩�整敲��慧楯�慳攬�潴楴攬��楢漱攬

andaugite.Thisispart1ya1tered,andbearsch1oriteandsericite.Thismembercomprisessma11分ag-

mentsofsha1e,whichissma11erthan3cminsize.and一旺agmentsarebrought缶｡mthe1owerforma-

tions.Manyporphyritic砒esintrudeintothisbmation.TheK6s6Tu任(Kato,1970)a1ongOmi

Riverisinter丘ngere(1withthismember.Themidd1ememberisdominant1ycomposedofgrey-bluish

greyand-esitic1ava,part1yoftu任一bre㏄iaand-1ithictu任.Theuppermemberismain1ycomposedof

andesitictu任一bre㏄iaandpart1yofandesitic1avaandtu任.AroundMt.Kamuriki.thismembercomrises

we1dedtu任.Bloc長sinthetu任一brecciaaremain1yofandesite,part1yofgreentu任andmudstone,

��捩��摧牡癥�潦��楯物��潭楮慮瑩��睥��牴潦��攀

湯牴��佩物��桴��物獣潭灯�摯晡�敲��物瑩�慶慷楴��牴�牡楮�

pyritebutnobiotite.Interca1ationsofsomewhitetu任1ayersareinthismember.Themidd-1ememberis

composedofa1teredamphibo1eandesitic1ava,partIyandesitictu肥breccia.Theuppermembercom-

prisessi1ici丘｡ateddacitictu任,tu任一brecciaand-1avawithquartzgrainsofwhich(1iametersare1_3mm,

anditsthicknessisvariab1e.Thetype1oca1ityoftheSusobana亙｡rmationisthecuttinga1ongthe

road缶｡mMt.KamurikitoSh巾hachimagariPass.Thethicknessofthisformationreachesmore

吐an900m.Asawho1e,itsuperposestheOagawa亙｡rmationwithconfomity,buttheuppermember

superposesthemidd1ememberwithpartia1unc㎝£omityaroundMt.Kamuriki.

㊧｡丁臨eK⑰醐蝉更⑪r醐銚量㈱consistsofsandstone,s包nd-ysha1e,cong1omerateandtheira1tema-

tion.The1owerpartofthis此rmationistu旺aceousandinterca1atedwithcoa1seams,andbearsp1ant

��異��瑰�瑩獣畴批��潭佩�由��癥��楴桵�潮景浩�批�效佩物

Vo1canicRocks(Fig.3).ThisbrmationsuperposestheSusobana亙｡rmation.Thetype1oca1ityof

thisformationistheroadcut血｡mAshinoshiriinOokaVi11agetoNagaiwa.Thethicknessofthe

おrmationattainsmorethan690mattheaxisoftheKomOiSync1ine.

7.丁脆O⑪幽e恥亙㎜就量⑬醜(PIio-P1eistocene)distributesinthewestoftheNakayamaFau1t.In

thestudiedareathis此rmationconsistsoftu伍aceousmediumgrainedsandstone,coarse-verycoarse

杲��慮��

窪.亙臨e職壼繍y認醐aV⑩亙｡訟赫｡盈⑩砥saredivided-intotwomem.bers,name1ytheHOiriyama

Vo1canicRocks(inthenarrowsense)andtheMitsumineVo1canicRocks.Theもrmerismain1ycom-

posedofb1uish-b1ackpyroxeneandesitic1avaand-basa1ticand-esitic1ava.In止e1owerpartofthe

member,basa1t-andestitevo1canicbre㏄iaandintermittentagg1omerate1ayersareinterca1ated.The

sizeofthosebre㏄iais舟｡m5to10cmonanaverageandthemaximumisabout60cm.Thematrixis

lithictu任｡Theb1acktwopyroxenebasa1tisdistributedatMt.HOiri,andandesitic1avaandvo1canic

bre㏄iawith1argeaugitecrysta1s(5-10mminsize)arerecognizedatMt.Tararawhichis1ocatedin

thewestofMt.HOiri.The1attermembercoverstheSusobanaFormationwithuncon£ormity,and

contactswiththe亘帥riVo1canicRocksatLakeHヵiri.The1owerpartofthismemberisbasa1tic

andesitic1ava,andthemiddlepartiscompo…edofandesiticvo1canicbre㏄iawithtu旺｡rtu舐aceous

sandstone1ayers.Thesizeofbrecciaranges缶｡m5to50cmindiameter,and-the長indsofitare

andesite.daciteandsandstoneoriginated血｡mtheOgawa亙｡rmation.Theupperpartofthismember

isofb1ackg1assyandesite1avawhicho㏄upiesthesummitportionofMt.Mitsumine.TheHOiriVo1-

canicRocks(inabroadsense)mconformab1ysuperposesthe亙｡mOiFormation乱ndtheSusobana

一78一�


andesitelava．TothesouthofH麺iriHeightsandaround　Mt．Kamuriki，this飼rmationisdividedinto

three　members。The　lowest　member　mainly　comprises　of　plagio－rhyolitic　tuff　and　lava　and　partly

dacite　lava　with　large　quartz　grains　ofwhich　diameters　are1－7mm，plagioclase，biotite，amphibole，

and　augite。This　is　partly　altered，and　bears　chlorite　and　sericite。This　member　comprises　small　ffag－

ments　ofshale，which　is　smaller　than3cm　in　size，and　fヒagments　are　brought　f士om　the　lower　fbrma－

tions。Many　porphyritic　dikes　intrude　into　this偽rmation．The　K6s6Tu仔（：Kato，1970）along　Omi

River　is　inte面ngered　with　this　membeL　The　middle　member　is　dominantly　composed　ofgrey．bluish

grey　andesitic　lava，partly　of　tufLbreccia　and　lithic　tuff．The　upper　member　is　mainly　composed　of

andesitictuf卜brecciaandpartlyofandesiticlavaandtuf［．AroundMt．Kamuriki，thismembercomrises

welded　tuff．Blocks　in　the　tuffbreccia　are　mainly　of　andesite，partly　of　green　tufr　and　mudstone，

especially　cobble　sized　gravels　ofquartz－diorite　are　dominant　in　the　Iowestpart　ofthe　member．To　the

north　ofH弓iri　Heights，the　lowest　member　is　composed　ofaltered　rhyoritic　lava　with　quartz　grains，

pyritebutno　biotite。亙ntercalationsofsomewhitetu£flayersarein　thismember．Themiddlememberis

composed　ofaltered　amphibole　andesitic　lava，partly　andesitic　tuff－breccia。The　upper　member　com－

prisessiliciβcateddacitic　tuff，tuff－breccia　andl3vawithquartz　grainsofwhichdiameters　are1－3mm，

and　its　thickness　is　variable．The　type　locality　of　the　Susobana　Form乱tion　is　the　cutting　along　the

road　fヒom　Mt。Kamuriki　to　Sh颯hachimagari　Pass．The　thickness　of　this　fbrmation　reaches　more

than900m．As　a　whole，it　superposes　the　Oagawa　Formation　with　confbmity，but　theupper　member

superposes　the　middle　memberwit五partial　unconfbrmity　around　Mt．：Kamuriki。

　　6。丁恥e鼠⑪賦瑠量For職魏恥聡consists　of　sandstone，sandy　shale，conglomerate　and　their　altema－

tion。The　lower　part　ofthis　fbrmation　is　tu価ceous　and　intercalated　with　coal　seams，and　bears　plant

fbssils。The　uppermost　part　is　cut　by　the　Kom巧i　Fault　and　covered　with　unconfbrmity　by　the　H弓iri

Volcanic：Rocks（Fig．3）。This　fbrmation　superposes　the　Susobana　Formation。The　type　locality　of

this　fbrmation　is　the　roadcut　f塾om　Ashinoshiri　in　Ooka　Village　to　Nagaiwa．The　thickness　of　the

fbrmation　attains　more　than690m　at　the　axis　ofthe　Kom勾i　Syncline．

　　7。丁睡O⑪蜘e恥朧且鋪量鋤（Plio．Pleistocene）distributes　in　the　west　ofthe　Nakayama　Fault．In

the　studied　area　this　fbrmation　consists　of　tuf瓶ceous　medium　grained　sandstone，coarse－very　coarse

gra血ed　sandstone．

　　8・丁翫e購脚且y題臨盆V⑪且c寵謡c璽⑪磁s　are　divided　into　two　members，namely　the　E勾iriyam＆

VolcanicRocks（inthenarrowsense）and　the　MitsumineVolcanic：Rocks．Thefbrmerismainlycom－

posed　of　bluish’black　pyroxene　andesitic　lava　and　basaltic　and，esitic　lava．In止e　lower　part　of　the

member，basalt－andestite　volcanic　breccia　and　intermittent　agglomerate　Iayers　are　intercalated。The

size　ofthose　breccia　is　fヒom5to10cm　on　an　average　and　the　maximum　is　about60cm．The　matrixis

lithic　tuf£．The　black　two　pyroxenebasaltis　distributedat　Mt．H勾iri，and　andesitic　lava　andvolcanic

brecciawith　large　augite　crystals（5－10mm　insize）are　recognized　at　Mt．Tarara　which　is　located　in

the　west　ofMt．H萄iri．The　latter　member　covers　the　Susobana　Formation　with　unconfbrmity，and

contacts　with　the　E勾iri　Volcanic：Rocks　at：Lake　H葡iri．The　lower　part　of　this　member　is　basaltic

andesitic　lava，and　the　middle　part　is　compo忌ed　ofandesitic　volcanic　breccia　with　tufror　tu伽ceous

sandstone　layers・The　size　of　breccia　ranges　ffom5to50cm　in　diameter，and　the　kinds　of　it　are

andesiteシdacite　and　sandstone　originatedfyom　the　Ogawa　Formation．The　upper　part　ofthis　member

isofblackglassyandesitelavawhichoccupiesthesummitportionofMt．Mitsumine．TheH勾iri　Vo1－

canic：Rocks（in　a　broad　sense）unconfbrmably　superposes　the　Kom茸i　Formation　and　the　Susobana

一78一

Fo1dsofMioceneFomationsinHligashi-Chiku㎜aDistrict,NaganoPre此｡ture,Centra1Jαpan(H.阻T0)

正OrmatiOn.

9｡幽醐曲帥⑱c忠sManyintmsiverocksaredistributedintheeastemareatotheMatsumoto-

NaganoLine.Forexamp1e,theKitayamaDaciteoftheOgawa亙｡mationdistributesatMt.

Kitayam,andandes三ticbasa1tsheetsinthesouthofMidarebashiVi11age(Eigs.2and6).Many

灯��物�摩步獷楴桎�南��摩��歩��慷��畳潢慮愀

��慴楯��歡��献

3｡侵鱈⑩亙⑰g量e詠咀Sを貢鵬｡重山亙紀s

3.且M1aj⑪亙逓⑭亙唖s

3.且.亙Taka缶Sync1ine

Thissync1ineisoneofthebiggestお1(1sinthenorthemFossaMagnaRegion.Inthestud三edarea,

on1yitssouthemendpartcanbeobserved-andd曲rmationofthesync1ineextends缶｡mtheAo嵐

FormationtotheOgawaFormation(刑g.7).

周��獎久�南慮��湧�瑯��慮��湧慮朱�猱��つ敧��

Limbdipsare舟｡m30to40degrees包ndthissync1ineisnear1ysymmetric.Minorb1dsdeve1opeinthe

睥��潦�楳��

3.盈.2NodairaAntic1ine

亙romtheBessho亙｡rmationtotheOgawa亙｡rmationarestrong1yparticipatedtothedebrm航ion

潦�敎潤�牡�瑩�楮�周�慳琱業��癥牴畭��慮杉��た��杲�猩楮��椀

亙｡rmationbutitshowsgent1edips(30degrees)inthesuperposed危rmation.Theaxia1p1anedip

towardstheeast,sothatthis北1disasymmetric.Becauseof1ac蛤ngine冊ectiveたeybed,the胎atureof

�楳慮瑩�楮��瑩��整��献周��摯晴��楣��楳�瑢��卡�慷愀

�畳��潮�

3｡且.3Kom箏iSync1ine

The1engthoftheaxisoftheKom軸Sync1ineisabout23km,andthe狐ia11inestrikestoN5.Win

��牴潦��剩癥爬�敎�楮��牴潦��剩癥牡�瑯丱�圭㈰�楮

thenorthempartofOmiRiver.Thissync1ineiscutbytheKom軸Fau1t.Thewest1imbissteeper

thantheeastone,andispart1yovertumed,thatis,thissync1ineisintensive1yasy㎜metric.Theaxia1

p1anedipstowardthewest.Itp1mgestothenorthabout10_20d-egrees.Itsd-e此rmationextends

舟｡mtheBessho亙｡rmationtotheKom軸亙｡rmation,butn.ottotheHOiriyamaVoIcanicRocたs.Many

minorお1dsdeve1opeinthesouthemareaofthisfo1d一(刑gs.7and-8).

3.且｡雀NomaAntic1ine

Thisantic1ineisnamedbyK0BAYAsHIandIs0MI(1950)わrthe丘rsttime.The1engthoftheaxisis

about22kmandstri長eofitisN15.EbetweenAidaRiverandtheNomaFau1tandN20.Winthe

湯牴�晴��由琮周��摩��瑩��中��瑩瑳��瑯�捨慮来��

��瑩潮睨楣��灰��物湧�整業敷��慮��晡由瑳睥�景��

Theaxia1distancebetweentheKom軸Sync1ineandtheNom包Antic1ineb㏄omesnarrowerinthe

�畴�周敢潴桷�琱業��数敲�慮��慳瑯��瑩捉楮�猱��楮�攀

de£ormationrate,andmoreasymmetrica1thantheKomOiSync1ine.ThisanticIinep1ungestothe

湯牴��畴㌰弴つ敧��楡��摩�瑯睡��敷�瑩��湯牴��愬��楮

一79一�

難

Folds　ofMiocene　Formations　in　Higashi－Chikuma　District，Nagano　Pre琵cture，σentral　Japan（H．KATo）

Formation．

　　⑭．臨醗鵬畳▽e胸eks　Manyintrusive　rocks　aredistributedintheeastem　areato　the　Matsumoto－

Nagano：Line．For　example，the　Kitayama　Dacite　of　the　Ogawa　Formation　distributes　at　Mt．

Kitayama，and　andesitic　basalt　sheets　in　the　south　ofMidarebashi　Village（Figs・2and6）．Many

porphyrite　dikes　with　NE－SW　trend　intruded　the　Bessho，the　Aoki，the　Ogawa　and　the　Susobana

Formations　are　ofremarkable　ones．

ま

轟導

3。　G㊧o亘09量c認亘s慮欝既硫盟蜜es 藝

3。亘Ma腰憲⑪踊s

　　3．且．且　Takafh　Syncline

　　This　syncline　is　one　ofthe　biggest　fblds　in　the　northem　Fossa　Magna　Region．In　the　studied　area，

only　its　southem　end　part　can　be　observed　and　defbrmation　of　the　syncline　extends　fヒom　the　Aoki

Formation　to　the　Ogawa　Formation（Fig．7）．

　　TheaxistrendsNNE－SSWandplungestothenorthandtheplungingangleislessthan30degrees．

：Limbdipsare丘om30to40degreesandthissynclineisnearlysymmetric．Minorfbldsdevelopein　the

west　limb　ofthis　syncline。

　　3。且．2　Nodaira　Anticline

　　From　the　Bessho　Formation　to　t五e　Ogawa　Formation　are　strongly　participated　to　the　defbrmation

of　the　Nodaira　Anticline。The　east　limb　is　overtumed　with　high　angles（60－80degrees）in　the　Aoki

Formation　but　it　shows　gentle　dips（30degrees）in　the　superposed　fbrmation．The　axial　plane　dip

towards　the　east，so　that　this　fbld　is　asymmetric、Because　oflacking　in　ef恥ctive　key　bed，the　fbature　of

th．is　anticline　is　still　unknown　in　detail　to　us。The　northem　end　ofthis　anticline　is　cut　by　the　Saigawa

Crushed　Zone．

　　3。且。3Kom勾iSyncline

　　ThelengthoftheaxisoftheKom菊iSynclineisabout23km，andtheaxiallinestrikestoN50Win

thesouthempartofAidaRiver，theN－SinthenorthempartofAidaRiverandtoN10。W－200Einthe　northem　part　of　Omi　River．This　syncline　is　cut　by　the　Kom弓i　Fault。The　west　limb　is　steeper

than　the　east　one，and　is　partly　overtumed，that　is，this　syncline　is　intensively　asymmetric．The　axial

plane　dips　toward　the　west．It　plmges　to　the　north　about10－20degrees．Its　defbrmation　extends

貸omtheBesshoFormationtotheKom弓iFormation，butnottotheH：巧iriyamaVolcanicRocks．Many

minor　fblds　develope　in　the　southem　area　ofthis　fbld（Figs．7and8）．

　　3。且．農　Noma　Anticline

　　This　anticline　is　named　by　KoBAYAsHI　and　IsoMI（1950）fbr　the且rst　time。The　length　ofthe　axis　is

about22km　andstrike　ofit　is　N’15。E　betweenAida　River　and　the　Noma　Fault　andN20。Win　the

north　ofthe　Noma　Fault。The　axial　trend　is　essentially　N－S，but　it　seems　to　be　changed　by　the　block

rotation　which　had　happened　during　the　time　when　the　Noma　and　the　Hakuba色ults　were　fbrmed．

The　axial　distance　between　the　Kom勾i　Syncline　and　the　Noma　Anticline　becomes　narrower　in　the

south。The　bothwest　limbs乱re　steeper　than　the　east　ones，but　the　NomaAnticline　is　less　intense　in　the

defbrmation　rate，and　more　asymmetrical　than　the　Kom勾i　Syncline．This　anticline　plunges　to　the

north＆bout30－40degrees。The　axial　plane　dips　toward　the　west　in　the　northem　area，but　the　e批st　in

一79一


thesouthemarea(刑gs.7and8)｡Itsdebrmationextends舟｡mtheBesshoFormationtotheOgawa

亙｡mation.Manyminor£o1dsdeve1opeintheeast1imbandthesouthemareaofthecrest(亙igs.9

現nd1O).

3.且.5NanatsumatsuSyncline

Thisfo1disnamedbyKAwAUcHI(1973)forthe£rsttime.This1ocatesontheeastoftheNoma

Antic1ine.Theaxisofthesync1ineis7たmin1engthandthestriヒesaboutN-S(1irection･Theaxia1

�慮��敲��癥牴楣��瑰�琱��楮��来�潴�湯牴�

about20-30degrees.Inthesouthemarea,theNanatsumatsu正au1td-eve1opesontheeastofthis

��楮�牡��楮��整物��潮朱��慳�業��票��潮��

thewestoneissteep.Itseemstobewarpedshapeintheendpart.Someminorお1dsd-eve1opeinaxia1

�牴潦��楮�

Itsd-eformationextends舟｡mtheAokiFormationtotheOgawaFormation.

3.亙.㊧Aid-aSync1ine

The1engthofthisaxisisabout8Lm,andthegenera1striたesoftheaxisisaboutN15.E.Itp1mgesto

��慮㈰�杲��數��牡��瑯��周��慮��

癥牴楣�慮��琱��獷��漱�慮摩瑳摩��慮㌰�杲��慮��睥�潮攀

20_30degreesintheOgawa亙｡rmation(neartheax三softhis缶1d),butismorethan60degreesinthe

�歩��瑩潮��浴��慴楯�潴��慷��瑩潮��湶漱癥搭楮�楳��

3.亙.7NishikibeAntic1ine

Thisisnamed£rst1ybyTANA鮎(1958).The1engthofth三saxisisabout6.5たmwithinthestud-ied

��畴睨漱��畴��灯牴�批啣��牡剥��捨��瀨��周敧�敲�

trendoftheaxisisNE_SWinAiyoshi,Minakami,Ya良yu.andAnazawaarea,andischangedtoN_S

orN5oW_S5.Einthesouthempartofthestudiedarea.Itsdebmationextends缶｡mtheUchimura

亙｡rmationtothe1owerAokilFormation.Asitp1mgestothenorthabout30_45degreesabrupt1y,it

deわrms1itt1etothenorthemarea.Thewest1imbdipsbetween30and60degreeswhere乱stheeastone

摩��ち��つ敧��瑩��楳慮瑩�楮��潮朱��整物��敍楮慫�椀

Routewhichis1ocatedinthenorthempartofthisantic1ine,thethicknessoftheAoki互｡rmation

捨慮来猱楴琱敢整睥��献�奡歹��睨楣�猱�慴��浩搭�数�瑯晴��

antic1ine,thethicknessoftheAoki亙｡rmation割1sochanges1itt1e.However,中eir1itho血｡ieMrevery

di茄erent缶｡meach1imb.Thatis,inthewest1imb,s乱ndstonean(1sandstonericha1temationare

d-ominant,whereasintheeastone,sandysh割1ericha1temationisdominant..

Itistheimportantfactthatthebrmerismorecompetentthanthe1atter.Inth,eAnaz包waRoute

whichis1ocatedinthesouthemp乱rtofthisantic1i血e,theKidosandstoneandcong1omerateMember,

whichisthe1owestoneintheAokiFormation,ofthewest1imbismuchthicたerthanthatoftheeast

one,andthechangeinthicknessoftheBessho正｡rmationismuchthesameasthatoftheKid-o

��敲�

3.且.窪KinokoyadaniSync1ine

周��晴��楮��畴��浩��物步��南楮��牴�畴

捨慮来��当楮��牴��楡��楳�浯�癥牴楣�慮��楳��来�潴�

north1essthan20degrees.Thedeおrmationextends缶｡mtheBessho亙｡rmationtothe工｡westpartof

theAokiEorm-ation.遇｡th1i㎜bsd三pin10_20degrees,and-thissync1ineissymmetrica1.Thethickness

潦��敲�牴潦��慴楯��牧�瑩��捲�瑰�琮

一80一�


the　southem　area（Figs。7and8）．Its　defbrmation　extends　fyom　the　Bessho　Formation　to　the　Ogawa

Formation．Many　minor　fblds　develope　in　the　east　limb　and　the　southem　area　ofthe　crest（Figs。9

and10）。

　　3。且．5　Nanatsumatsu　Syncline

　　This　fbld　is　named　by　KAwAuGHI（1973）fbr　the癒st　time・This　locates　on　the　east　of　the　Noma

Anticline．The　axis　ofthe　syncline　is7km　in　length　and　the　strikes　about　N－S　direction．The　axial

plane　is　generally　vertical　but　partly　dips　towar（1the　east　in　the　north　end。It　plunges　to　the　north

about20－30degrees．亙n　the　southem　area，the　Nanatsumatsu　Fault　developes　on　the　east　of　this

syncline　in　paralle1．This　syncline　is　asymmetric　strongly　and　the　east　limb　is　nearly　horizontal　while

the　west　one　is　steep．It　seems　to　be　warped　shape　in　the　end　part．Some　minor　fblds　develope　in　axial

part　of　the　syncline。

　　Its　defbrmation　extends　f士om　theAoki　Formation　to　the　Ogawa　Formation，

　　3．L6　Aid，a　Syncline

　　Thelengthofthis　axisis　about8km，andthegeneralstrikesoftheaxisis　about：N15。E。Itplunges　to

the　north　less　than20degrees　and　extends　gradu批11y　to　the　north　end．The　axial　p1乱ne　is　almost

vertical　and　partly　dips　westwards．This　is　open　fbld　and　its　dips　less　than30degreesシand　the　west　one

20－30degrees　in　the　Ogawa　Formation（near　the　axis　ofthis　fbld），but　is　more　than60degrees　in　the

Aoki　Formation．From　the　Bessho　Formation　to　the　Ogawa　Formation　are　involved　in　this　syncline．

　　3．且。7　Nishikibe　Anticline

　　This　is　named鉦stly　by　TANAKA（1958）。The　length　ofthis　axis　is　about6．5km　within　the　stud．ied

area，but　whole　length　is　about13km　reported　by　Uchimura：Research　Group（1953）．The　general

trendoftheaxisisNE－SWinAiyoshi，Minakami，Yakyu，andAnazawaarea，andischangedtoN－S

orN50W－S50Einthesouthempartofthestudiedarea。Itsdefbrmationextends食omtheUchimura

Formation　to　the　lower　Aoki　Formation．As　it　plunges　to　the　north　about30－45degrees　abruptly，it

defbrms　little　to　thenorthemarea．Thewest　limb　dips　between30and60degreeswhereas　the　east　one

dips　between10and30degrees，that　is，this　anticline　is　strongly　asymmetrica1．At　the　Minakami

Route　which　is　located　in　the　northern　part　of　this　anticline，the　thickness　of　the　Aoki　Formation

changes　little　between　both　limbs．At　Yakyu：Route　which　is　located　in　the　middle　part　of　this

anticline，the　thickness　ofthe　Aoki　Formation　also　changes　little。However，ちheir　litho魚cies　are　very

dif琵rent　fピom　each　limb．That　is，in　the　west　limb，sandstone　and　sandstone　rich　altemation　are

dominant，whereas　in　the　east　one，sandy　shale　rich　altemation　is　dominant．

　　It　is　the　important　fact　that　the　fbrmer　is　more　competent　than　the　latteL　In　t五e　Anazawa　Route

whichislocatedinthesouthempartofthis　anticline，theKidosandstoneandconglomerateMember，

which　is　the　lowest　one　in　the　Aoki　Formation，ofthe　west　limb　is　much　thicker　than　that　ofthe　east

one，and　the　change　in　thickness　of　the　Bessho　Formation　is　much　the　same　as　that　of　the　Kido

Member．

　　　3。且。8　　K．inokoyadani　Syncline

　　　The　axis　oft五issynclineis　about6．5kminlengthandstrikes　to　NE－SWin　thenorthempart，but

changes　to：N－S　in　the　southem　part．The　axial　plane　is　almost　vertical　and　the　axis　plunges　to　the

north　less　than20degrees．The　de｛brmation　extends　f｝om　the　Bessho　Formation　to　the　lowest　part　of

the　Aoki　Formation．Both　limbs　dip　in10－20degrees，and　this　syncline　is　symmetrical。The　thickness

ofthe　lower　part　ofthe　Aoki　Formation　attains　largest　in　the　crest　part。

一80一

｣､

H-Hiji･iゾmo･olc㎝i“舳

��浯晩潮

��歩��潦楯�

伀

s版h“hi

mogo了if596

��潦楯�

�啣�業��浯晩潮

�一

舳顯眺NW･汕｡｡

キ

�

､!

Shuno[戸5ge

�

�

△

舳.komoUm

ム

舳.H

､!

巛

ゾ＼“一

肌Oki

!ノ､1

�

■いト

攀

�

�

細��

∵U

＼

.､一

㌻

キ

℀

�椀

�

◎

一胴

∫脆

ε

�

o＼

州

�

珍

串

洲

--L帰仁言2

｡.'`

�

十

�

/十一

帀

��浯礰

�㈳�

亨舳

老

少

一

〆隻㌧!

刀lI--1-1-

件

�

粘

-中巾-

落

�

OεO

稀

伀

.･･后2

/舳･…

�

⑭ξ

籔

一w

独

�

�

サ

寺な/

o』oZ

酬那た厚マ

｡!1

�

o･I

�

枇

≠

≠

券

犯

㌀

チ'､.

"〃7

/〃〃『

｡紗

-紗

い

一

�

一

一

一

�

壮

即

U皿

一1C

�

伀

�

�

攀

�

�

愀

爀

攀

�

攀

�

�

最

酬

�

�

�

09Ukhizb曲｡

歹

��坤�

F.1d､｡fMi.c､｡､F｡､m｡･i｡｡｡i･Hig･･hi-Chik㎜･Di…i･･,N･g…P･･胎･･…,C･･…lJ･p･･(H･K…)

刑g･8

堤･'

≒心＼､.

煎＼､㌧

ざ㌻

■へ1二､

＼

＼

ノｰノ

"/!＼､､.=､〆〈＼1

��

･へ

字

�

1泌一､

＼1

アス戸､

＼

“＼./

芯

拭'

心＼/

心ノ/･迅.

徽〆〃ハ＼

獅影然

.､肘､

グ田

〃

〃

�

─

]多

1,/吻

�ね

区ヨSANDSTONE

匿ヨSSRlCHALτ

匡…ヨ引ALERlCHALT

皿]]SHALE

Th,b1｡｡kdi包g･｡m･f･h･K･m巧iSy･･1i･･泓･d･h･N･㎜･A･･i･1i･･i･･h…th･mp･･tof

��摩��

3.2M1萄⑧亙担盆醐亘歯

3.2.且

卡��睡�畳��潮攀

Thi曲｡1｡｡｡｡｡｡｡｡｡d｡･｡N-Si･･h･…di･d･…,･･d･･NE-SWi･･h･･…h･････…Thi･･㎝･i･

､h.wi｡｡｡｡i｡…｡p･血･1･｡･h･･i･,･h･mm･1曲･1･i･f･mdi･･h･･…h･m･…(･h･…t･ideis

.p),b｡･･h･････…£･･1･i･b･･di･･h･m…h･m･…(･h･w･…id･i･･p)･Th･･…h･dzoneis

&om50mto1OOm-inwid-th,andm乳nyminor由u1tsandjointsdeve1opewithinthecrushedzone･

Th･1･y…i･･hi････････…y･…p･･dp…1y･･･…m･d･

3.2｡雲

Kon〕二iji亙au1t

This血u1ttr㎝dstoN-SorN1O.E-S10WandcuttheaxisoftheKom帥Sync1inewithacute

､｡｡1｡.I｡･h･･…h･m･…,･h･w･…id･i･g･･…11･d･w…di･･m･･im･m･1ip･…h･･150m･In

一81一�


弔

{雫

“

ゲ£紬

稽

.一筆

や

肯｡

ま

山Z:OZ>ω⊃uつト〈Σ⊃uつ←くZ〈Z

や

亭

#メ戸

＼へ崎

＼

ン

γ

ザ

乎

却

γ亨

ダ

ダザ

暮､

㍍＼

＼

＼

多

ゲ㌻

㌢

ゲ

ヅ

＼

＼

＼

㌦＼

や

､〆

如｢8

←"葬

ダ噺

ｰ

ダ呼

乎

ダ

〆

�

第

○

争

〆

ぎ

十乄協低�剃低�位��

十乄奓��

ALT巨RNATlON

替

�

�

〔｡

告

別g.9

�捴潮楣��牴�捲�瑯晴��瑩�楮��湧��剩癥爀

一82一�

�

圭㌃

ヌOζ一らωくZO〔Z阿

騒鰯｡

皿晒｡｡､ヨ､

S･S･&･･ηg

髄

S州y･わ｡'｡

900ρ

ノ

一

℀

℀

�

�

一

�

“

�

一

島

議

あ＼霧

一一

一一■･一

!/ノ.`

//多

工�

ノノ2

/〆

〆一

一一

夂

､/玄概

←共

熱

堀

一

℀

讐柳川w〃

簿

･`

��

烹"

.･.･

●･

㌫

組

�

　

�

　

〰

�

㌀

�

～

　

　

F紅10

為ヘヘヘ～へ酬…�

Fo1dsofMioceneFomati㎝sin囲gashi-Chiku㎜包Distr五｡t,NaganoPrefecture,CentralJapan(H.KAT0)

��楳摯�慮摩瑳��浯��慮��

therefore,be1ievedtobeapi∀ottype由u1t.Thedis1ocationcomestobebiggertow乱rdsthenorth.At

theentranceoftheMaruyamaRoute,itsopen£au1tp1anewhichcutsthecong1omerateoftheKomOi

亙｡rmation,ands1ickensid-esonthep1aneareobservedasshownin刑gure11(A).

㌮㈮㍎潭�慵�

Thisfau1ttrendstoNW_SEandbe1ongstoaた三ndofwrench由u1t.Thoughtheheaveofthe

northemeastb1ockcanbeestim乱tedtobe700mヨthethrowoffau1tison1y1essthan50m(thesouth

睥��歩��温�

3.2｡垂Namtsumatsu賄u1t

ThisismmedbyKAwAUcHI(1973)おrthe£rsttime.Thefau1ttrendstoN-Sa1ongtheaxisofthe

��

←K◎舳』1FAU[TN20E,80-88W

1m→

�

�

師､12S

伀

こ逝ぺ10ξ･･

剏�

(膠)

乏��汎�

[=コSANDSTONE

鹿騒S･N･∵S｡｡･･01･･…

亙ig.11So]=αeprof皿esofr口inorf包u1ts.

(A)showsminortectonic£au1tswhichcut此eKo加軸Fau1tontheMaruya㎜aroute.

(B)showsaminorreverse£au1twithcrushedzonenea.rthecrestoftheNomaAntic1ine.

一83_�


��瑳畭慴獵��

周敷�瑳��楳摯�慮��瑳��灰��瑯��牧敲�〰洩瑯��晴��

島u1tisthesameastheAida肪u1t.

3.2.5Aida亙ault

Thisfau1trunsinNNE_SSWdirectiona1㎝gtheAidaSync1inecuttingtheBesshoFormati㎝.The

s1ipofwρstsidedowncomestobe1argertothesouthandthemaximumva1ueof200misobservedin

thewest.Thesouthendofitisnotc1earbecauseofbeingcovered-witha11u切a1sediments,Thenorth

�摯晴��慵�楳湯��慮��慵�摯�湯��楳��楯�潴��楣獨�瑯�琮

Kokuzo.Thethicknessof砧rmations,especia11yinthe1owerOgawa亙｡rmationandtheAo良iForma-

tionchangesabrupt1yateachsi(1eofthis由u1t,thatis,intheeastsideofthisfauItthethic良nessofitis

�楮�牴��瑯晴�睥�潮�

3.2.煽Hakuba亙auIt

This曲u1tisin危rredfromthedis1ocationofthesandst叩eandcong1omerateofthe1owestpartofthe

AokiFormation.anda1sothatofthefo1daxisoftheKom巧iSync1王neandtheNomaAntic1ine.The

��摯晴��慵��物步�潅久�南��灣潭�瑯��牧敲楮�敷�琮周��

三sdis1ocatedtotheeast.Themaximums1ipis700m.

3.3M虹鮒醜棚｡施欄

3･3･亙SedimentaryStructures

Deおrmationsduringthetimeofsed-imentation乱rebrmedbycurrentsandgravitationa1おrce

caused-bythemovementsofthebasement.Inthestudiedarea,theinitiationand丘na1企aturesof

m勾｡rstructuresmaybea冊ectedbytheinitia1此aturesofthenepton.Therefore,itisnecessaryto

describeandanaIyzethesedimentarystructuresinordertogetmore申｡w1edgeaboutinitia1con-

ditionswhichcausedthetectonicb1ding.Inthissense,theauthorintended-tostudysuch由｡tsasthe

m㏄hanicsofs1umpingstructures,c1asticdiたesandbomdimge.Theout1ineofsedimentarystructures

ofthestud-iedareawasreportedbyTANA鮎功α1.(1973).TheauthorcouId-ad-d-somead-ditiona1(1ata

totheirworkasshowninFigure12.TANAKAθ〃.pointed-outthatwhentheBessho亙｡rmationandthe

AokiEormationweredepositing,currentswere舟｡msouthtonorthinitsdirection.Theauthor

strong1ysupPortstheiropinion(Fig.13)･

Thedistributionofcrossbed-dingsand-watercurrentsrestored血｡mthemareveryinterestingas

獨��摩湧��畤��数��牴��搭楮��

andthemaximuminc1inationsoftheおrsetbedsareveryconcordantwiththedipsof1imboftheNoma

Antic1ine,buta1soneighbouringminor缶1ds,andtheinc1ination-sofaxia1p1anesofs1umpingfo1ds.

Furthermore,thed三stributionofcros§beddingsarethesameasthose⑪f∬エi皿｡rお1ds.Minorfo1ds

whosewavc至engthsare1essthana此wmetersinth帥tud-iedareaareassumedtobemost1ys1umping

fo1ds.Thereasonswhytheautho･jud-9edtheo･iginofminorfo1dsaregivenas刷1ows:

(1)Thoseminorわ1dsdeve1opeinspeci丘eda1temationsofsandstone勧ndsandysha1eoftheAo嵐

亙｡rmationand-theBessho亙｡rmation.

(2)Someoftheminorお1dsaretruncated-bythesuperposed-strataasshowninFigure15.

(3)Their免aturesaremost1ysimi1artype(Fig.16).

(4)They舟equent1yexisttogetherwithothers1umpingstructures(Fig.17).

(5)Theyhavea1argecurvaturewithout血acturing.

一84一�

Fo1dsof=MioceneFormationsinHigashi-Chiku皿a･District,NaganoPrefecture,Centra1Japan(H.KAT0)

�

寺

ξ

�

灘8岨OiOO{b1OCk5hO1e

念SlUmp5frUdure

φSl･･｡舳

㍗DC【o;;bedding

OOgowoFormo“on

AAokiI=o【molion

�攵獨��潦楯�

喰v＼

/､

A/､μ･川･･'＼

'､､

ムO

伀

尽､伸

○心

恋

�

念

1念

当

山

〉

て

吻

威企

途ゑ

ム公

血

A～

念

盈

㌧

瓜

止

血

止

鉦

底

㌔

'愈

念

鐵

一

!､;〆

嵐

念威

�

◎

�

ゑ

亙ig.12

伀

�

�

ThedistributionofsedimLent刎ystructures.

�

��票慶�潢�摩湧猱��

Some･minorio1dsmaybetectoniconesasshownin亙igure18壇romtheir此atures.Theirdistribution

isshowninFigure12,anditisinterestingthataxialtrendsofs1umping刷dsarepa11e1tothatof1arge

t㏄toniconessuchastheNomaAntic1ineandtheKom填Sync1ine.

C1asticdikesareobservedwithinstratigraphichorizon缶｡mtheupperpartoftheBessho亙｡rmation

tothe1owerpartoftheOgawaEormation,乱ndthosetendstobeiorme(1nearthetectonicboundaries

-85一�

地質調査所月

報(第30巻第2号)

AドsANs;1旦･さ､､ノわ必･一二…

傳1!

･1ソ寺､

､Ol

刀

い佃

塁Rl

､､､s.ポ〕､ズ

}･工/

･ll'…い･

ミ･ζノ

ペ!

TA触W

翰

稀

φ

''ノ

'㌧･'

､'

◎､･'

へぺs

･二sム｡A

Bκ

＼

一

匀

�

刷g.13

R-RiPPlem◎rkS-S◎lemork

B-Bessh◎ド◎mci刊◎nA-A◎kiド｡rm◎刊｡n

◎一〇g◎w◎肝｡rmclfi◎n

Pa1aeo-currentdirectio㎜estimatedfro㎜ripp1e㎜arksandsomekindsofso1emarksinthe

AokiForm乱tionandtheBesshoEorma.tion.

ofthebasement,thatis,theSaigawaCrushedZoneand-theCh06Up1iftingZone(亙igs12and21).

Themateria1sofdikesaremost1y丘negrainedand-coarsegrainedsandstone,part1ycong1omerate,and.

��慴楯湯晳慮�瑯�慮搭獨��周敷��潦摩步��浯��慮㈶�慳獨��

刑gure工9,buttheir1engthsare㎜㎞ownyet.Manyjointsdeve1opeinc1asticd1kes,andsomeminor

由u1tscutdikes.C1asticdikesaremost1yp1amerinshapeandcutthe1ayerswithrightang1eorhigh

慮朱��楣摩步��獨��慢�㌮周��楮瑯�整��楮

亙igure20.Type1isおund-inmanyp1acesinthestudied-area,anddeve1opesintheuppermostpartof

the遇essho亙｡rmationandinthe1owerpartoftheAokiFormation.Type2isobservedat1oca1itygin

一86一�

句｡匡蜆｡妻｡｡､､｡句｡｡昌四け一｡目吻一､碁凹吻手Q睾嚢票一員看彗･茅雲毫･Q彗§一喜§肩内亘

一

＼

㌧＼写

��

��

��

��

㈭�

㈭�

㈭㌀

㈴

㌭�

��

��

�㌀

4斗

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

�㈰

�㈱

�㈲

仏23

�㈴

�㈵

�㈶

�㈷

�㈸

仏29

�㌰

�㌱

仏32

�㌳

��

��

��

��

��

��

��

��

��

��㌰一

��し

丸ぅ��

�し�し

丱し�し

��ぅ

串し�ぅ

��圀

��

��し

�

串し��

串��

��

丸ぅ�こ

�

�ぅ�こ

丸ぅ�し

丷し��

丸ぅ�ぎ

丸し�ぎ

丸ぅ��一

��

丷ぅ�ぎ

丸し��

串ぅ��

�

丷ぅ�こ

��こ

丶��

丶ぅ��

��し

丶��こ

�

��し

�ぅ��

��

�ぅ��

�

�し��

�し�し

丶ぅ�こ

丱��

�ぅ��

�し��

�し�ぎ

��ぎ

�し�ぅ

地質調査所用

丁乱b1e3


��潦�慳瑩�楫��

坩��

(･m)

亙eature

�步��畤�

��物�晏��瑩�

㌰

�

㈰

�

�

�

�　

�

�

㈵

��　

㌭�

�

�

�

㈰

�

�

�

㈵

㈰

�

�

�

㈰

㌀

�

�

㈰

�

㈰

㈵

㈰

�

�

�

㌰

�

倀

㈰

㈰

�

㈰

㌀

�

�

㈰

�

�慮敲

�慮敲

坡�

�慮敲

�慮敲

�慮敲

坡�

�牴��

p1an･･

楲�杵�爀

��琱祷�

�牴��

坡�

p1乱ne･

楲�杵�爀

睥摧攀

�慮敲

p1an･･

�慮敲

�慮敲

坡圀

坡圀

�慮敲

坡圀

灬慮敲

i･･e即1ar

�慮敲

p1･n･･

�慮敲

�慮敲

�慮敲

�慮敲

irre帥1ar

坡圀

p1乱ner

�慮敲

�慮敲

楲�杵�爀

�牴��

灬慮敲

p1an･･

�慮敲

part1yw･

�牴��

灬慮敲

�慮敲

�慮敲

浥�献献�洮��

浥��

mユed.s.s.

��

��献献

��献献

r皿ed.s.s.

1=ned一.s.s.

�渮��

浥�献献

��献献

��

��

nユed.s.s.

��献献

nユed.s.s.

��

�渮��

��

nユed.S.S.

��献献

��献献

r皿ed一.s.s.

加ed.S.S.

��

��献献

工ned.s.s.

r匝ed.s.s.

�爨��献献

��

rlユed.s.s.

��献献

浥�献献

r匝edL.s.s.

��献献

工ned.S.S.

工ned.s.s.

r[工ed.s.s.

��

1=皿ed.s.s.

nユed.s.s.

浥�献献

��献献

r[工ed[.s.s.

r皿ed.s.s.

r皿ed[.s.s.

1=[ユed.s.s.

1=匝ed.s.s.

�洮��

u.m.B.亙.

��

u.I正1.B.F.

�洮��

1.A.正.

u.m.B.亙.

u.工皿.B.F.

��

u.nユ.B.F.

�洮��

u.m.B.亙.

�洮��

�洮��

u.1=皿.B.正.

��

�洮��

u.m.丑.亙.

u.m.B.亙.

u.m.B.亙.

��

u.nユ.B.F.

u.皿1.B.亙.

u.nユ.B.F.

��

��

��

u.r皿.B.亙.

�洮刮�

u.m.B.百一

u.m.B｡亙.

�楮��

u.1=口.B.E.

u.n1.B.亙.

u.m.B.亙.

u.1=α.B.亙1

�洮��

��

u.n1.B.正.

��

u.I皿.B.F.

�洮��

u.n1.B.亙.

u.m｡.B.亙.

��

u.一n.B.F.

u.rα.B.亙.

却�捴�攀

舵a.Ctured,

�牴�晡由瑩湧

��

10乱dCaSted

part1y1a工nin包ted

we11£au1ted

周楳摩步�瑳

猱畭�漱�

晡由��

晡由��

�牴�晡由��

�慣��

猱畭��

�牴�晡由��

晡由��

一88一�

Fo1dsofMioceneFormationsinHigashi-Chikum凱District,NaganoPre此｡ture,Centra1Japan(H.KAT0)

��潮瑩��

��楴�

��

��

坩��

�洩

亙eature

�步��畤�

n1ateria1fOr工natiOn

却�捴�攀

��

��

��

��

�

��

��

��

�㌀

�

��

��

��

�弱

��

��

��

�弱

��

�弱

��

丷し�こ

丸ぅ��

��

串し��

�し�ぎ

�し�ぅ

�し�ぅ

�し�し

�し�し

�し��

�し��

丱��

��

倀

倀

�し��

��

倀

��

串ぅ��

]=寸40E,72二■≡=

�

�

�

�

�

�

�

�

㈰

㈰

�

㈰

�

倀

�

�

�　

�

㈰��

�

�

�慮敲

�慮敲

�慮敲

獨��

plane･

�慮敲

W現Vy

睥摧攀

��攀

灬慮敲

p泓rt1yw.

�牴��

坥摧攀

�慮敲

�慮敲

�慮敲

�慮敲

�慮敲

楲�杵�爀

p1乱ne･

�慮敲

�慮敲

一皿ed.s.s.u.rα.B.F.

��

c.s.s.u.n1.B.亙.

c.s.s.u.rΩ.B.亙.

浥�献献��

浥�献献��

med.s.s.㎜.A.F.

㎜ed.s.s.㎜.A.F.

浥�献献洮��

med.s.s.㎜.A.F.

��孥�献献

��

��

㎜ed.S.S.

rαed.s.s.

��

r皿ed.s.s.

�

浥�献献慮�

��

nユed.s.s.

��献献

洮��

独.A.亙.

洮��

��

u.A.亙.

u.rα.B.E.

u.r皿.B.F.

��

�洮��

��

��

part1y島u1ted

楮捉畤楮杣��

f土agnユents

杲�楮最

�牴�猱�健�

*LocalityNo｡丘sshowninFig.21.

辛u.m.B.F.me副nstheuppermostpartoftheBesshoFormation.

*u.B.亙.meanstheupperpartoftheBesshoFormation.

*1.A.F.meansthe1owerp服toftheAokiFormation.

*m.A.F.me副nsthemiddlepartoftheAokiFormation.

E]S･N…◎雌

□…圧

広

■.

■■

■･

�

･

�

･■

..●

曳.:

〆

�

､凛

一■

･

.ニマ･.

一

�

!“'

.･?:

＼

N'.譜･ぺ

“.

い

'ど.

榔ク言㌶淳1

.㍉

�

o■､

里'.

与･

�

�朮�

Anexampleofthetrunca.teds1u㎜ping北1dintheAo虹亙｡rmationnearAsδ.

一89一�


Fig.16So㎜epro日1esofs1u㎜pingfo1dsintheAoki亙｡m=1包tion.

砧gure21.Itbecomestobethimerdownward,an(1iswaWwhereitmeetswiththe1owerend-1ayer.

Itdeve1opesinthemidd1epartoftheAoki亙｡rmationanditsmateria1sarecomposed-ofsandstone,

��晰��敲瑩��歳慮��捫�晳慮�瑯��摩�物�瑩潮潦癡物��捴��

describedaboveisshownin珊gure12.TheirdistributionisrestrictedintheBessho亙｡rmationandthe

Aoki亙｡rmation,and-inthewestofMatsumoto-NaganoLine.Itisinterestingthattheirdistribution

arecontinuousa1ongtheaxisoftheNomaAntic1ine舟｡mthesouthtothenorthregard1ess

�牡瑩杲慰�捨��潮�

TheSaigawaResearchGroup(1966)pointedoutthatadisturbedzone,named“SaigawaDisturbed

-g0一�

Fo1dsofMioceneFormationsinHigashi-Chiku加aDistrict,N包ganoPre胎｡ture,Centra1Japan(H.KAT0)

�漉�

岨��

､､��

､､�＼�1��

＼�山='J�､��

//�=�1'�一,�､､㌔

､､�㌔�一��

､��

o�＼1m�“��

一��

ゾ��

一��

｣��

1･��

1･�..4....｡..��

��

I�.咀一反一1一｣'■�ゾ�⊥�

1'�ミ��

§一�1ノ�'��

1�■��

㊦�.｣�ノい�/一�■

1.･�一.�呈��

1.�s�肝��

､･��

1.�◆��

､��

､1･'�o�1…��

自��

��

､.��

､��

､･��

､��

��

､��

㌦.��

､��

､'��

､��

ド�㌧ジ�〆�一ト�

o�1而�､､��

､�一�､､�､�＼

v�｢��

｣��

､''�､､��

､･㌧�o�lm��

皇��

如�/�､��

/嚇粍�1''��

､.��

､.��

､��

､.��

､��

1･��

伽♂/�､��

ド�'��

1･��

��

嵩�ド.�カ��

』国�11.i��

��

��

��

��

'�'�I･'.I��

γ�'�i.一��

'�'�1一.��

��

'�｣`��

士�'��

'�lI�[コAOKlRORMATlON��

“'�'�1･��

℉��

'�'�'.二'�口BESSHOFORMATION�

'�'�一ò��

��

'･�｣｣BEbDlNG��

＼�'�'��

⑧＼�'��

'�司･.�｣一CLASTlCDyKE��

�儿伉�

�卌�偆��

＼�'�仙寸､��

'�靱�山��

～一�｡SLUMPSTRUCTURE��

'�◎�'��

'�木｡'�'�一�

��

＼1o＼�O��

稉��

'�工��

ω��

��

'�号��

､��

〕�500m�.'τ･�Σ･�

伉��

と��

＼･��

､.��

､��

Fig.17Theroute㎜apofNagamineDr包gRoad.

��慳瑩�楫��楮杦��慮摯�敲猱畭��捴��敷��

嬢,嵐,◎,△副ndO帥esymbo1sofc1asticdikesineacharea(SeeFig.20(B)).

一91一�

晦18

地質調査冴ガ鞍

似仏1･1柵

��圀

一

(鶏3･巻

鎗2号)

伽他戸1柵

帆80W

鰯

ニヘヘ地∵

㈰

コ0

　

,1ζぐ㍗∵

､92､�

Fo1dsofMiocene亙｡rmationsin冊gashi-Chikum乱District,NaganoPre£ecture,Centra1Japan(亘.KAT0)

TY昨1.

L◎c.4

〕㎝

＼

念

◎

◎

ム

　

A1◎

血

一

1圏

二〕

0◎

◎

　

◎

鱈

◎

△

⑧⑱

鱈

鰯ム

亀

竃O

念

公

ム

⑧

企

嵐0

◎竃

TYド匠2'し◎c.9

〴っ�

�

040㎝

�

�

べ

�

･

�

�

�

�

〴っ�

�

導悉

ち竃:

､

乃

�

一

qu｣11一コ

五ig.20Twotypesofc1asticdikes.

(A)showsexamp1esofType1clasticdikesofwhichdike㎜a.teria1se血p1aced血｡mthe1owerpart.

��敲��煩散瑩潮潦�慳瑩�楫��

(C)showsexa=mp1esofType2c1asticdikesofwhichdikemateria1se㎜p1aced血｡皿theupperpart､

(D)showsstereoprojectionsofaveragec1asticdikesandlimbsofminor£o1ds.

一g3一�

崖踊灘蛛号泣難一警長警竺

佇��

FORMAηON

��

�前��一

BESSHOFORMAη0N

鰯□皿

｡

⑧

鱈

十

浩�爀

浩�爀

�慓瑩�

�畤楮

nOrma!faUけ

reVerSefauけ

摩步

南敬�

orρ1nchand

却��攀

轡μ

�

亀

�

�

�

�

攀

井

○

鮭

Th･di…ib･･i㎝･f曲･･･…｡｡i､､t､｡｡｡｡､､､.

＼

＼

愚

愁

一

訴

亙ig.2

ふ

一

一

��

��

FoldsofMioceneFormationsinHigashi-ChikumaDistrict,NaganoPre此｡ture,Centra1Japan(H･KAT0)

Zone"ofwhich1engthisabout30隻mandwidthis1.5_2.0kmwiththetrendofSSW_NNEdeve1opes

楮�敷�瑰�瑯晴��畤��獺潮��猨�牴��敲�浥�潦��楯畳��

潦�摩浥��晡由瑳��敲癥�周��歡�散�湧��楴�晡捩�慮�

geo1ogica1structurescanbe砧undatthiszone(亙AT0.1970).SaigawaDisturbedZoneisarti丘｡ia41y

de丘nedbecausethedisturbedzonecomprisesnoton1yinitia1highdipareaduringtheperiod-of

�灯�瑩潮��批��牴散瑯��瑳�畴��楳�楢畴楯湯晳��捴��

數��湧��条睡�畳��潮攬慮��潴��楳潦�敎潤�牡�瑩�楮��

part,おrexamp1e,inAkashina,theirdistributioncomestobeindistinct,andthesimi1artendencyis

��杮��楮��楳�楢畴楯湯晳��楮杳��湧�敎潭��楣��

�楳湯��牴��慴��散潮捥�牡瑩潮�晳�業��特��捴��牲�灯��楴桴��

changingin1itho臨｡iesandthicknessremar長ab1y.Apartofthis曲｡treportedbyKAwAdcHI(1973)

andKA三AHARA(1973).Theauthorwi11d五scussaboutthiszone1ater.

�畤楮��楮捨��睥��捴��敲癥摩��瑩潮潦��潮��

sha1eneartectonicboundaryofthebasementb1ocksasthesameasc1asticdiたes.Theirdistribution

concentratesintheboundaryoftheOgaw包andtheAoki亙｡rmations,andoftheAokiandtheBessho

��慴��

Boudinsarec1assi丘edintoおurtypes旺｡mtheirfeaturesasおuows:

Type1isrectangu1arbodyandits舟acturep1anesareveryc1earwithoutplasticneckingdown.

Type2is1enticu1arbod-y.Somesurroundingmateria1sshowconsiderab1ep1astic且｡wage,andsome

boudinshavemany血actureswithoutanydis1oc乱tion.

Type3isrhombicbod-ywith1inear舟acturep1anewhose1engthsareabout50cm.Boudinsofthis

��敲癥搭潮�慴�条浩��慧副��

Type4ispinchandswe11structure.Inthistype,p1asticaowageisdominant,andeach缶agments

��潴��牡��

Inthestudiedarea,tbistypeofboudiniso丹enobserved.

��捴楯�潦�潮条瑩潮潦�捨�畤楮楳�牡��瑯��敲楮朮

㌮㌮�楮�晢��

Itisgenera11ysaidthatvariousお1dswhosetypesandsca1esared冊erenttoeachotherscoexistin

��敦漱摩湧��潭敧��猨味�い��慮��慶整物�瑯来��攀

understandingaboutmajor缶1ds血｡mana1ysisofminorお1ds,buttheyseemtobefai1ed.Theone

reasonisthatitisd冊｡u1ttoestimatetheoriginoftheseminorfo1dswhosewave1engthsarebetweena

fewmetersanda£ewtensofmetersasa1readydescribedabove.Theanotherreasonisthatitisa1so

(1i冊｡u1ttodescribethe£o1dswhosewavelengthsarebetweena此wtensofmetersanda虻whundred-

metersasthestrainimagesofmajor£o1ds.Asa危｡t,itwasnotsu冊｡ientto(1escribethethreedimen-

siona1(1eおrmationofminorb1ds.Theauthordescribedandana1yzedthedistancebetweenaxes(that

is,ha1fwave1ength),the1engthofaxesandthemaximumamp1itudebecauseofthedi舐｡u1tyof

constructingtheexactpro日1esofminor比1ds.

(1)C1assi丘｡ationanddistributionoftectonicminorお1ds:Thedistributionandtypeofminor比1ds

楳��潭散��楴桴��捴潮楣��楮捥猨�朮㈲�晴��摩��浩湯�漱��散��

si丘edas比11ows血｡mtheirshapesandaxistrends.

��湯�漱�潦�楳��楳�楢畴�楮��㈮周��癥��楮�攀

uppermostpartoftheBesshoForm航ionandintheAokiFormation.TheaxistrendstoN_San.d一

一95一�


7･冬N

｡ぐ｡

瓢＼1曲1､ぎ

1!ト･

皿1.一

,'.'一'`'

1機

く

�

い

〃

'ク

一

ノ皿

℀

〃

｡｡S鼻O

佩㈳��

亙ig.22Tectonicprovincesinthestudiedarea.

�散潮��慮�楴桴��潦��漱��楲摩�物�瑩潮楳湯��癥��數慣琱�周慴楳��

deve1opec1ose1yinthesouthempartoftheKom填Sync1ineandintheeast1imboftheNoma

�瑩�楮�

Type2:Theseminorb1dsaredistribute(1intheareaIVo冊igure22.Th?ydeve1opebetweenthe

upperpartoftheAo蛤亙｡rmationan(1theSusob包na亙｡rmation.Theinc1inationsof1imbsare1ess

�慮㈰�杲�献周��潅彗�

��㌺周��楮��楳�楢畴�楮��

Theydeve1opebetweentheupperpartoftheAokiFormation.andtheOgawa亙｡rmation.The

楮�楮慴楯�潦��慮㈰�敧��楳��

Type4=Theseminorお1dsaredistributedintheareaVIof刑gure22.Theydeve1opebetweenthe

midd1epartoftheBessho亙｡rmationandthe1owerpartoftheAoki亙｡rmation.

周��獲��歡�祷�慮搭楮摩�楮捴��祭��湧整潴�湯牴�畴�浥��来

tothesouth.Theyd一曲rm1itt1eandstrong1yasymmetrica1.

(2)(Ha1f)Wave1ength,name1ythedistan㏄betweenaxes:The&equencydiagramofwave1engths

ofType1minor危1dsisshowninFigure23(A)｡Thesewave1engthsaremost1y1essthan500m.The

averageva1ueis334m.Thewave1engthsofmajor缶1ds,thatis,thosebetweentheKom填Sync1ineand

theNomaA皿tic1ineare命｡m2たmto6km.Thereおre,wave1engthsofmajorお1(1sareabouttentimes

一96一�

亙｡1dsofMiocene亙｡mationsin囲gashi-Chiku㎜aDistrict,NaganoPre胎｡ture,Centra1Japan(旺KAT0)

��敲匀

100派

��

｡nUmb…(B)

15一

�

�

家

�　

�

�

�

�

�

�

50010001500.05∞100015002000.

WAVELENGTH⊥ENGTHOFAX-lS

Fig･23The缶equencydiagramsofwave1engthsand1engthsofaxisof皿inor刷dsinAream.

as1ongasthoseofminor㎞1ds.Asminorお1dsofType2,3and4aremost1yirregu1ar,theirwave1engths

�散�湧慢��祷��捲楢��

��晡�猨娩�

Th･舟･q･…ydi･g･･m･fth･1･･gth･･f･h･Typ･1mi…丘･1d“･･i･i･･h･w･1･亙ig…23(B)･

Theyo㏄upied77%between200mand500masthesamecaseofthewave1engths.

�楳湯��湧��晡�獷�捨�敢整睥��〰ね慮��〰��楮�楳�畤��

��

��湧�潦�楳癥�畳��晷慶��桲慴楯�

Inordertoinvestigatethehorizonta1企aturesofminor比1ds,the1engthoftheaxisversustheha1f

wave1engthratioisshownin亙igure2全The旺equencyoftheratioofType1minorb1dsisshownin

一g7一�


(第30巻第2号)

1�N∪mbers��

��〰─

��

��

��　

��

�■��

��●��

伉��

��

�

��

1015z/タ

Z=[eη9fh

み;

◎f◎x.1･5

��敢敦睥��

冷

�

(圏)

Noo､

山u｣u｣

0-O-0･

��

1_←I一

Fig.24Therangesof1en郎hofaxis-ha1fwave1engthratioofminortectonicfo1ds.

(A)showsthe旺equencydiagr乳mofaxis1ength-halfwave1engthratioof㎜inorfo1dsinAreaIII.

(B)showstherangeofaxis1en郎hs-ha1fwave1engthratioof㎜血｡rfo1dsinAreaIV,V乱ndVI.

一98�

｡｡1｡､｡｡Mi.c､､､｡｡m､･i｡｡｡i.Hi｡･･･…i㎞㎜･･i…i･･,N･････…胎･･･…C･･…lJ･…(旺趾T0)

刑､､､､｡｡(･).･…｡･｡･i･･…H･･･････…i･･舳････････…;････…11i…i････…'

h｡｡i､｡｡｡｡1此｡｡｡｡｡｡｡f･h…mi…わ1d･…p･11･1…h･m勾･･舳･･

｡｡､､､｡i｡､｡･･｡｡｡2,…d･mi…危1d･･････…i･亙i･…2･(･)･T･･･…m･･t1･1･ssthan3･5

b､｡m｡､､｡h､､1Mi｡｡､1.1d｡｡･th･…｡｡･･d…1…w･･k1･･亙…h･㎜･…i･･曲･･…d･th･｢e1a一

､､｡､｡､､｡､､､1､､二､｡､｡｡､､､､､｡･｡｡｡｡1｡｡､畑…i…1････…1･…舳i…舳･i…t･･････…

､､､i｡｡･･｡｡､1｡･mi｡｡…1･･･…岨･･…1･･肌･･････････････…4･･h･･i･･th･di･t･ib･t三〇nofthe

､､｡i｡､､､c1､､､冊､db｡･･｡1i｡｡w･･･…1･･i･1…i･…i･…1･････…1････…f････…1…tenti㎜es

､､1｡｡g｡｡di｡･･･…b･･w･････…f･h･wh･1･mi…比1d･i･th･･t･di･da｢ea･

亙u､｡｡､､m｡､､,｡･､1｡｡｡･･｡｡…i･･････…1･････…i･･証･･････…1･････････…三･11･mino｢£o1ds

｡･･｡｡､1･｡｡｡･･i････････････…1ヅ･･…i･i･･…1･･…i…i･三･di･id･･1･asesshowin･as

｡｡｡｡｡､.亙｡､､､､㎜｡1｡,･･｡｡･1･･…mi･･…1･･i･････…1im･･･…K･m箏iS…1i･･(m･･kO)･andin

､｡､､､i,1｡､｡｡｡…｡N･m･…i･1i･･･…◎･…i･…(m…⑧)･････…i･百三･…26･Thedistance

b､｡w､㎝､､､､､､､m､｡｡b｡｡｡｡｡･｡･…di･d･｡･･d･…f･h･1･･g･h･f･･i･･Th･…h…tw…1･eshave

notc1osebutroughconI1ection･

(5)(M･･im･m)Amp1i･･d…d･h･di･…㏄b･tw･enaxes:

｡i｡､､､･･｡･｡｡｡･･…1･･i･…m･･im･m･m･1i･･･…舳･･i･t･…b･････…e･of㎜i口｡｢'o'ds

i､｡｡｡､1.･｡mi｡｡…1････････…1im･i･…K･m巧i･…1i･ら･hi･h…d･おmedst｢on･1篶出e

�〰　

一

“

ω

一』｣1000

�

�

�

出

……=

畠

固

�　

山

里

婁

δ

�

亙ig.25

作1

㊥

燦

㊥㊥

㊥

㊥

囲

㊥

㊥他

ム窟

会二､､

･成〉努

歳へ

卓

､淋

�

蚤

欺

�

も十

◎1N.mf･･m･t･･Sy…

◎2Nis舳ibe^同ti･

◎3NomoAn刊･

◎一k･mijiSγ…

1落一

一Wnorfo1d5inAreolV

㌃10舳n町fdd5inA削V

㊥MinorfoldsinAreoV1

��〰�〰〰�

圧NG珊OFAX1S(Z)

Th､､､1､｡i｡｡b､｡w､㎝｡｡｡｡1｡｡帥h…dh･旺w…1･･帥h･･fm勾･･舳･･d㎞…制ds･

一g9一

��


(第30巻第

2号)

ω

山m

葦300

Fo1dso(MioceneFormationsinHigashi-Chik㎜蝸District,Nag勧noPre此｡ture,Centra1Japan(亘.KAT0)

午�

�吮

SH､

��

SH､

�吮

SH､

ALT｡

Sト1.

ALτ.

午�

U｡Ù.4U.5��OZ04��uZ∪白U.b�ω040b�0.ZU4■�

��一

＼)＼��､�＼��

��＼��

℉��

4�､､､�…･!＼��

儿℉��

�■��

�/�.､.��4!�＼��

��■v■■'�､､､��〕/1��

��儿℉��

��ノ1�/λ､��1＼��

��I.I�1ン/��

��!/1/��へ!､�1＼�

��111�＼1'＼1�

�

�㈰��

扣

儲〴儲〴〶

�

Q2.406020ム外1

1■2'一■2-3………3-4一･一4-5一･･一5-6{1～6:AxEsoF州1N0RF0[Ds〕

亙ig.28Thea㎜p1itude-ha1fwave1engthratioofminorお1dsinthewest1i㎜boftheKomijiSync1ine.

レ6shows眺esofminorfoldsshowninFig.7.

1argerm乱ximumamplitud.ebecomestobe,the1argerthedist包n㏄betweenaxesa1sobecomestobe.

亙urthermore,theratioofmaximumamp1itudeversusha1仁wave1engthis1argerasshowninEigure27

(markO).Onthecontrary,inmimrお1dsofthewestintheNomaAntic1ine,the1argerthedistan㏄

betweenaxesbecometobe,tbesma11ertheratiobecomestobeasshowninFigure27(mark△)｡玉n

minor比1dsinthe脳ia1partoftheNomaAntic1ine,theirre1ationismc1earbecauseof1itt1echange

ofthedistancesbetweenaxes.亙igure28showstheratioofamp1itud-etoha1£wave1engthofminor

お1dsofthewest1imbintheKom軸Sync1ineateachstratigraphichorizon.Astheminor缶1dsp1unge

tothenorthandthestrongestd曲rmationofeachb1darenota1waysrepresented虹tbesame

捲��散瑩潮��獵��浥�潢��楮捴�

遇utther乱tioincreasesattheboundary舟｡msandymudstonetothea1temationofsandstoneand-

sandysha1e,and.theratiod.ecreaseatthebo㎜dary伍｡mthea1temationtothesand-ymudstone.

Minor比1dsreachthemaximumamp1itude-wave1engthratioatsandstoneora1temationinmudstone.

3.3.3Minor血u1ts

Thoughmanyminor由u1tsdeve1opeinthestudiedarea,themutua1re1ationsbetween缶1dsand

minor胞u1tshavenotbeenc1earyet,sinceithasbeendi舶｡u1ttomakec1earwhethertheoriginofthe

浩湯牢��搭業��特��捴潮楣�

Inordertogetmorecomp1eteknow1edgeabout比1dingm㏄hanismtheauthortried-toana1yze

minor魁u1ts.亙｡rthepurpose,theauthormadeanassumptionthatthe血u1tha曲ngdisp1acementof

morethan20cmand由u1tc1ayorcrushedzoneareconsid-eredtobeoftectonicorigin.Someex-

amp1esofminor鼠u1tsareshownin刑gure11.Minor血u1tsshownin亙igure11(A)areobservedin

thecuttingoftheMaruyamaRouteneartheaxisoftheKom巧iSync1ineinthecong1omerateof

一101一�


theKom軸Eormation.

Thoughtheirdisp1a㏄mentsarebetween1Oand20cm.theycuttheKomヵiRau1tandtheyh乳ve

猱楣步��慮��由瑣��

Thereおre,theyaret㏄tonicorigin.Someofthemcutpebb1esintheOgawaFormation.Minor

reverse臨u1tswithcrushedzoneshownin亙igure11(B),areobser∀edinthea1temationofs乱ndstone

andsandysha1eoftheAo良iFormationinthesouthofMacchiVi11ageneartheaxisoftheNoma

�瑩�楮�周��瑯�慫楮摯晴�歩湫��慮祭楮�晡由瑳潦��癥��

nearthisoutcrop.Becausetectonicminor由u1tsmost1ycutthestratawhichd-ipsttep1y,thedisp1ace-

menta冊erthe£ormationofminorfau1tisunknownand-theirordersoftheformationarenotdis-

tinguished.Butsomeinteresting由｡tsarenotedas£o11ows.Minorreversefau1tsarerestrictedinthe

睥�潦�敍慴獵浯瑯�慧慮�楮��楮�杵�㈱��浴�潮捥�牡�瑯��

�牴�晦漱��潮�慣琬浩湯��慵��潰��睨漱��摩��

3･毎醐aをs醐⑪t⑰一料aga皿⑰L虹e

HIRA眺YAsHI(1969)pointedout&omtheana1ysisofgeo1ogica1structuresthattheremarkab1e

捨慮来��散瑯��潮摩瑩潮��慳��晴�猱楮攬睨楣桲��

旺｡mMatsumoto-Aida-thewestofMt.HOiri-Mt.ChausutoNagano,Thushenamedthis1ine

“Matsumoto-NaganoLine".This1inea㏄ordswiththe“fau1t1ine''namedbyH0NMA(1931).In

thestudiedarea,this1inetrendstoN-S,name1y血｡mMatsumoto-AidaFau1t-theaxisoftheNanatsu-

matsuSync1inetothewestwardofMt.HOiriasshownin亙igure7.

Tectonicandigneousactivitiesintheeastemarea乱reverydi伍erent舟｡mthoseofthewestem

��慓晏�佗�

(1)Minorreverse血u1tsare1imitedinthewesternarea孕sdescribedabove.

(2)Majorfo1dsandminor血u1tswithstrongde此rmationsarerestrictedinthewesternareaand

湯�楮��慳��

(3)Theaxistrends,p1mgesandthe飴aturesofminor先1dsareregu1arinthewestemareabut

��敲�牲敧由�楮��慳��周��晡��敲獵��摩�慮捥��獲慴楯

ofminor比1dsinthewestemareaisd冊erent£romthatintheeastemarea.

��漱��捲�歳��楴攬慮��楴��潮��物捴�楮��慳��

��楮杳��摩�物��摭�琱��睥��

乱S竜亙軌｡重剛亙a亙A醐包亙ys孟s

4.亙亙醐遇灸触⑧醐竜亀亙｡血盟亙惑｡竜⑧rs⑫董遮⑫亙副蟹

Inordertoinvestigatethemechanismofお1ds,itshou1dbeknownthecbaractersand-distribu-

tionofstressesandstrainsa伍㏄tingthetectonicsystemwhichinc1udesthe砧1ding.Themechanism

of比1dingmaybeclassi丘edintotwocategories,theyarebuck1ingandbend三ng.Thebuck1ingfo1(1s

are缶rmed-bythehorizonta1compressionessentia11y,andthebending㎞1dsareおrmedbytheverti-

ca1movement.Natura1io1dsare砧rmedbythecompressionwhichhasvariousang1estothe1ayers

asUEM1J趾andTA鮎HAsHI(1974)pointsout.Therebre,itisneededtoc1ari吋the趾ndamenta1

charactersofthesetwotypesof刷d-inord-ertodistinguish先1dsinnature.The趾ndamenta1charac一

一102一�

亙｡1dsofMioc㎝eFomationsin剛gashi-Chik㎜aDistrict,NaganoPre胎｡ture,Centra1Japan(H.KAT0)

tersofthese危1dsmaybe1imitedtoもrms,thicknessandstress-strainrelationsshowingas冊1ows:

4｡亙.夏Charactersof危rms

Thecontrolfactorsおrmingfo1dsarethemovementofbasements,ducti1itycontrast,thicknessratio

潦��整��楮��整�琱�敲��潮�浯湧��敦慣瑯��浯�業灯牴慮��潢�

servab1eoneinnatureisonlythemovementofthebasements.Ifthebasementb1oc長sup1i丹di伍er-

entia11yeachother,thecover1ayersarede如rmed1ikeboxshapedb1ds.Ifthe1owerboundaryis

deおrmedtobesinusoid-a1,thebendingお1dsshowthesinusoid-a1shape.Asd-escribedabove,the

此rmsofthisbendingtypefo1dsarecontro11edbythed三sp1acementofthebasement.Asthedeforma-

瑩潮�浥�潢敷�步物��摩�捴楯湯�灰敲�癥�楴獨��數�楮��搭�睡癥�

�湧�牡瑩�潭�瑯��爬慮��楮��業�湧��浥�潢��来物��摩�捴楯湯�灰敲

�癥��楮�杵�㈹�

Thecontro1血｡torsわrmingbuck1ingb1dsareducti1itycontrast,thicknessratioofcompetentand-

楮��整�琱�敲�浥慮獨��湧慮�潯渮周��潦�楳��癥��獨��潢��

nusoida1bymanyexperiments(BI0T,1961;CURRIEθ～1.,1962;RAMBERGandSTE閉ANss0N,1964;

HUDLEsT0N,1973;KAT0.1975).Buck1ingb1dsaremoreperio(1ica1thanbending㎞1ds.Butac-

cordingtoWILLIs(1894)andJ0HNs0N(1969),buck1ing比1dscanshowthemn-periodica1shapeif

theinitia1deHectionsexist.This由｡texp1ainsth乱tminor缶1dswhichseemtobebucHedarenota1-

wayscontinuous.Inmu1ti-1ayeredbuck1ingお1ds,thewho1e1ayersharmonica11y北1dtogetherinsome

◎…

b･一一…㍉

､､＼

､

G一…"`.一'吐一'`＼

､､､

d'･二二''一こ}･･一＼＼

6.'･･'''一1.

早一･一･1.一1'

(μ/伽茗100,ε･一20%)

�

戀

�

攀

昀

篶1(1)

�

＼lA＼1瓜＼/ゑ�

儿

■�/＼

/�＼

/�＼

��

��㌰��

��

lNTE皿1^へBANGLEÀ)

A&erI糊口A,Y.andSIMAM0■o,T.(1974)

亙ig･29Theidea1izeddistributionofthea㎜p1itude-ha1fwave1engthra･tio,andinter1i㎜bang1eof

�敢�摩湧景��

一103一�


{o〕

��､､､2｡､伽

｡��底

戉�一

��底

｡��1ノ�

搉�一

��

昉�工

9��イ

■1��＼

i�/ユ��

j�1＼��

��

お[(⑧)

…雛回叙･Z幸三さ;}'･1≠一･･一･･〃套§･§C｡阯舳百肚"晒

欄■奪糞葦葦葦ぎ鮒苧榊

1b〕

�

AfferC∪rrie｣.B.efol.(1962〕lNTE皿1MBANGLE(金)

亙ig.30Tbeide乱1izeddistributionoftheam.plitude-ha1fwave1engthratio,andinter1i㎜bang1eof

thebuck1ing£o1d.

cases,butinothercases,variousb1dswhosewave1engthsaredi伍erentdeve1ope(RAMBERGand-

STEpHANss0N,1964;HA趾,1967;KAT0.1975).Inbuck1ing危1ds,itshou1dbeexaminedthatthe

��楴畤�睡癥�湧�牡瑩��業畭慴�散潭��祥��潭��楴��敲��

慮朱��楮業畭慴�散潭��祥牡��楮�杵�㌰�

雀｡亙.2Charactersofthickness

��楮杦漱��楮��整�琱�敲楳�整�浥�慴�散��潦慮瑩�楮攬慮摩瑩��楣步�

atthebottomofsync1ine.Thethicknessofthecompetent1ayerchanges1itt1eexceptinmuchde一

缶rmedb1ds(IKEDAand-SHIMAM0T0.1974).

Inbuck1ingお1ds,thethicknessofthecompetent1ayer1sa1itt1e1argeinthehingeexceptatthe

casewhichthecompetencycontrastishigh.B㏄ausetheinitia1thicknessisnot㎞owntous,itisvery

di冊｡u1ttoestimatetochangeofthicknesscausedbytectonicmovement.Asamatterof血｡t,thick-

nessesofeach1imbsareo冊endi冊erenteachotherinnature,thereおre,theaxisoHo1d1ocatesin

thep1a㏄wherethetbicknesschangesremarkab1yatthetimeofdeposition,whichisa冊ectedby

��瑯晴��浥��

伽･3Charactersofstress-strainimage

Stress-strainimageswi11bediscussedinthissection&omthenatura1de危rmed1ayersandthe

數�物浥��獵�献

亙irst,thebuck1ing£o1disconsid-ered.Thestressdistributionofthe血ee-1ayer一£o1d-mode1isana1yzed-

批十�げ��

A㏄ordingtohispaper,thetangentia1stressistensionstressinthecrest,anditミhowsthemaximum

va1ueinthecorepart.Buttheshearstresspara11e1tothe1ayershowsthe㎜aximu㎜va1ueatthe

-104一�

Fo1dsofMiocene恥rmationsinHigashi-ChikumaDistrict,NaganoPre此｡ture,Centra1Japan(H.KAT0)

iniectionpoints.DIET瓦RIcHandCARTER(1969),andS亘IMAM0T0andHARA(1976)ana1yzed-the

sing1e1ayer㎞1dmode1byusing丘nitee1ementmethod.Itisinterestingintheirworたsthatthepat-

�浯晴�浩��物��散��潦慮瑩�楮��慶攬��硴��

缶rceishorizonta1andthattheminimumprincipa1stressismost1ycompressive.

Second･,thestressandstrainpatternofthebending£o1d-isconsid-ered.IKEDAandSHIMAM0T0

(1974)d-escribedthestresspattembrbendingexperiments-Theyconc工udedthatthemaximumcom-

��癥��楳��敲瑩��潴��祥物��捲�瑯晴�慮瑩�楮攬��潴�略楮��浥牡��

Thatis,themaximumprincipa1stressishorizonta1tothe1ayerintheimer肌｡anditdisappe肌as

the1ayershorteningincreases.Intheお11owingsentenses,wecons三dertheexpected-minorstructures

伍｡mthese紬｡tsdescribed･above･亙｡rthebucた1ing刷d,norma1曲u1tsandtens三〇五jointsare危rmed

inthecrestofantic1ineandreverse肪ultsand.minor比1dsd-eve1opeinthecoreand/orininHection

灯楮瑳睨��散潭��潮�慳瑩獨�戮

Minorstructures拓rmedbycompressivestressgenera11ydeve1opeinthewho1eareabuta1itt1e

i･･h････…f…i･1i･･wh…h…mp･･…y･････…i･1･w,b････…h…mp･…i･････…p…11･1

tothe1ayerisdominanton1yintheinitia1stageofm勾｡r比1ding,the£or㎜ationofminor刷dsare

…t･i･t･di･･h･i･i･i･1…g･･Thi･曲･･i･･1･…pP･…dbyH･d1･･…'…p･･im･…(1973).

Ontheotherhand,inthebendingお1ds,someminorわ1dsde∀e1opeinthecoreofsync1ineas

thede£ormationcomeswea止erintheouterarc.

乱2盗触認里ys量s⑲f醐認j⑩r愈⑬亙認s

Themorpho1ogica1parametersofb1dsareimportant,becausetheyshowthedebrmationr飢eof

砧1ds.Theyareamp1itudeandd-istancebetween㎞1daxes.Bec刎seofshowingthemechanismof

危1ding,theyhavecharacteristicspatia1distributions.There此re,itmaybepossib1etodiscussthe

mechanismoffo1ding旺｡mtheseparameters.

鉱且Th･…i･･f(m･･im･m)･mp1i･･d･…h･di･t･…b･･w････…(h･1fw…1･･g･h)

Th･･…i･･1･h･･g…f･hi･…i･･f･h･K･㎡OiSy･･1i･…d･h･N･m･A･･idi･･･…h･w･i･乃g一

��楳��牴��牡瑩��業畭慴�敢��祢整睥��楡��

亙｡rmati㎝s(attheKidoMemberwhich五scomposedofsandstoneandcong1omerate),andatthe

OgawaandtheSusobana亙｡rmations.Thehorizonta1changeofthisratiooftheAohand-theBessh0

Formationsi五｡rosssections6,7and8areshowninFigure32.Theratiois1arger趾｡㎜theeastto

�敷�琮��牡瑩�猱�来�楳瑩�琱�潴�睥�潦��慓��楮�

This胞｡tsuggeststhattheoriginofお1ds1ocatedinthewestoftheMatsumoto_NaganoLineis

di舐erent缶｡mth包tintheeastofthe1ine.

先2.2Meanshortening

Itisdi冊｡u1ttodrawtheexactpro石1ebrm勾｡r危1(1s,there比re,meanshorteningcaI1notbeshown

數慣琱��晢��畤��敲慴��浥慮獨��湧

va1uescanbegotrough1y.MeanshorteningoftheKom蚊Sync1ineandtheNomaAntidine三s

獨��周楳癡�敲�捨��業畭慴��捨楳��爀

intheAoki亙｡rmationandattheOgawaandtheSusobana亙｡rmationsassameasthecaseofthe

��楴畤��睡癥�湧�牡瑩�

乱2.3Dipsof1imbs

Dip…i･･i…㎝･h･…t･whi･h1･p･･p･･di･･1･･…h･b1d･････…h･w･i･亙ig･…33,34,35

�〵�


��◎mp舳e-W◎鴨1e鴫吐竈◎舖0�meOnSh◎r甘帥1��1n甘erl㎞b◎ngle

��O.1α2Q30405�1020304050��405060708090100110120

1･■“2:譜��唾��㊧�

�◎c仁◎��1

�o.篶��1

■◎◎��1

9屋』∋◎吻』��1

��

��､

��⑧��⑧�ム

ζ�』��

◎�⑩��

●舳��

由��

◎��

ε�嚢��も｡

』��

◎��

L��爾��

�･】』��私＼

◎�』Φ■■��

参�ぷ■■��

◎�よ��

①�吻��

◎�◎��

�吻��

��⑧�㊥��△A

��

�◎��

'篶��

�◎��

�ε��

�』��⑧��

�◎��

』��

��竃�⑧��

■■��

以��

��

<��＼��

��㊥��

��､�＼㌣��△息/■

��爾��

��/��⑧�

��㊥��

�ζ��

�◎��

'鶉==��/⑧��/�

�◎��鱈��底

��/�/��＼

�ε�/�/��＼

�』�/�/��＼

�◎�/�/��､

�』��＼

�◎��

よ��

�ω��

�吻��

�Φ��

�漉��

◎ζ』◎3'篶ε◎よε��

∪』∋£��

亙ig.31Thedistributionoftheamp1itude-ha1fwave1engthr批io,皿eanshorteningandinter1i血b

ang1eoftheKomψSyncliI1eand㎞eNomLaAnt三｡1三ne.

and36.下血｡ughdipsonthesametectonic1eve1arenota1waysp1otted一,thed.i伍erenceofheights

a1ongtherouteisashtt1easigmred一.Dipsof1imbsoftheKom功iSync1ineareshown三n亙igure33.

DipvariationoftheKom軸Sync1inea1ongOmi.Riverisshow皿in刑gure33(A).Dipsofthewest1imb

��敲��数��癥牴楣�慮��琱�癥牴畭��晴��敧�琱整��

thoseofthewest1imb,butmorethan50degrees.Dipsof1imbsoftheKom坤Sγ㏄1inein亙kezawa

ROuteareshown三n亙igure33(E).

Theeast1imb三smoregent1ethanthewest工imbinthecaseof(A)of亙igure33,andcomestobe

gent1erapi汕y｡亙igure33(C)showsdipsinHakubaRouteanditshowsthesametendencyasthe

-106一�

亙｡1dsofMiocene亙｡r㎜ati㎝sin貫igashi･Chiku㎜aDistrict,NagamPre胎｡ture,C㎝tra1∫a脾n(旺KAT0)

�

�

��

�

�

�体卓��低�

�体匀

7Ki･･koyod㎝ihigo･hト州f伽

8.Mi廿｡ke-Aoki

1･Komiji-Nomo

㈮�浯彎潭漱�杯獨椀

3･Nomohigosh-Aid0

��摯�椵�歩�

5･Nishikibe-Kinokoyodoni

6･Ki･･k･yod｡･i-Kimkoγ･do･ihigo･hi

�体卓��低�

　

舳8＼

圀

ヨ

�朮㌲

㈳��

Thehorizonta1changeofthea狐p1itude-ha1fwave1engthratiointhecrosssection6,7and8

shownin亙ig.40.

�　

�　

�

�

�

圧70

δ60

�　

�

コ40

㌰

㈰

�

��■��一�U��

◎��

㈰��

�㊥��

lO�鍋�I��1��

��1��一�■�1��

��

lO��1��1�■�.��

;O��γ!⑧肝㊥㊥↑㊥㊥歯㊥㊥㊥圃⑧1㊥��1�1�司��

��⑧��

70��㊥⑧��

��⑧亀�1�紳�ト��

50��⑧�一��㊥1��

��㊥㊥⑧爾⑧㊥て⑧⑧圃㊥��1�㊥�趨�鯛�

��⑧��⑧��

50��㊥⑧㊥��㊥紬㊥�㊥��

��1��1�1�障��

��1��11㌔､1��㊥��

40��⑧㊥�

��㊥��

30��1��I�.�1�㊥�

��I��㊧1�個��㊧

20��㊥��

��一�1��

��

��

�

�楳潦�浩��

⊆_｣km

A:dipsalo口gOmiRiver,BldipsontheIke2awaroute,C;dipson此e亙aku1〕amute,

D…dipgonthe◎gud出晩wamut6.

囲g.33DipvariationoftheKo皿軸Sうmc1ine.

一107一�

◎

�

�

�

圧

･一60

　

��

�

･一40

｣

㌰

㈰

�

�


�

(第30巻第2号)

�

��

��

��/｡二��1�

��

��

��1��■��

�漉�潯��

��

�潯��潯漉��

��

�漉�漉��漉潯

��

��｡｡1､二��㍉｡1��騨1も｡｡ooい��OO�o

��

��漉��

��神��o��

��1��k二｡�

��o��o��oo�oo�oo⑪�

��漉��

��漉�

��潯��漉��

��I��■�

��

��

��

一AxlsofNoma-Antldlneし==｣km

A:dipson此eNomaVillageRoad,B:dipsa1ongO㎜…River,C:dipsonthemute肌rossYagosh丘andMatsu.

瑯浥��汯湧��剩癥�

刑g.34DipvariationoftheNo㎜aAntic1ine.

◎

�

�

�

�

〶　

〵　

�

二i40

㌰

㈰

�

��〔��

,��ド��1��

��

��

��一��.��I��

�･1��1��◎��

��Φ�

■��

��.��1��◎◎.�血o�

��1��1��･2�⑭�

��.��1��◎�Φ�

�◎��亀1◎｡◎��二｡◎｣◎1�ΦΦ�

��

■��1･��･91｡��㌃ト��

��I��1�◎�.��Φ

��I��◎��◎◎�Φ�

��◎◎◎�o:��

�

�

�

卜､⑩

､ぷ､､Φ

Φ

1J1Φ8

榔一A.I･･fN｡･･t･･m･t･･Sy.dI｡･』■km

D-Ax1sofAldaSyncいne

A:dips飢Kats皿a,B:dipsalongOmiR畳ver,CldipsontheroutefmmN五sh五jδtoBes5ho,

D=d三psonthemuteacrossIwaid5.

Fig･35DipvariationoftheN…㎜atsu1matsusynclineand/ortheAidasy皿c1ine.

caseof(B､.刑gure33(D)showsdipsin◎guch三zawaRoute.Thewest1imbd-ipssteep1yandispart1y

�敲�浥�畴�散慳琱業��敧�琱整��睥�潮��㌨�慮搨�獨�摩�

insandstoneandcong1omerater㏄ks.亙igure33(温)and(C)showdipsinsandysha1eanda1tema-

瑩潮潦��潮��昱業�潦�敎潭��楣��楮�杵�㌴�

�杵�㌴��楡瑩潮潦摩�楮�敲��慣��噩�慧��潦�敷�琱業扣潭�

tobegent工etowardtheaxisandtobehor三zonta1intheaxia工part.Theeast1imbdipssteep1ynear

the拙a1partbutcomestobegent1erapid1ytowardtheeast.Eigure34(遇)showsdipsa1ongOmi

_108一�

Fo1dsofMioceneFo･㎜･ti･h･i･冊…bi-Chik･醐･Di…i…N･･痂･…胎･･…,C･･…1･･｡｡｡(亙.K｡｡｡)

◎

�

�

��

δ60

�

�　

④㊥

コ40④､

㌰

η

�

��

�

�

!､｡

㊥

ド1

④

�

Φ

④④

�

･L

AxisofNishikibeAntidneC一一Kinokoyada.11i

Ol㎞Sy･di･･

自

A:dip1㎝th･m･･････…Y･kyO,Bldip･㎝･h･････…m･･Mi｡｡k副mi,

C=dipsontherouteto出eeastofYak河.

刑g･36Dip∀･･i･･i㎝･f･h･Ni･hikib･A･･i･1i･…d/…h･Ki･･k･y･d･･isy｡｡1i｡｡.

Rive･･Di…fth････…dw…1imb…m…b･･…1･･･････…｡刑｡･･…(･)･･｡w｡･i｡､i｡

the｢outea･･…Y･…hi･･dM･･･…m･･Th･w･･t1im･･････…h･w…mi比･m･h｡｡｡｡i｡･i｡､

a･d･ith･･1imbi･g…1…w･･d･h･･･…Fig…34(D)･h･w･dip･･1｡｡gAid.Ri｡､｡.Th,w｡､｡1imb

comestob･g･･t1･t･･h…i･b…h･･…1imbi･･…1…b････…fd･･｡1･pm｡｡･｡fmi｡｡､舳､.

Fi･…35(A)･(B)･･d(C)･h･wdip･i･･h･N･･･…m･…S…1i･…d(D)･h.w.di｡､i｡｡h,Aid､

��

亙i･･｢･35(A)･h･w･di･･･…K･･･…i･･h･O･･w…m･･i･…d･h･w…1im･i｡｡･｡｡｡､､｡h､｡

theeast1imb･･d･･m･････････････…h…1･･･…N･･･…m･･…｡･･1i･･.･i｡｡･｡･･(･)｡h｡｡､

dip･i･･h･A･ki亙･･m･･i…1･･gO㎡Ri…,･･d･h･w…1imbi･｡･｡｡p｡｡｡1it.1､｡h､｡｡h､､､､｡｡｡､.

亙ig…35(C)･h･w･dip･i･･h･Og･w･亙･m･･i㎝i･･h･･･…舟･mNi｡軸･･｡B､､､h｡､｡d.h,i,

va｢iati…fdip･i･･imi1･･…h･･･…f(A)･mig…35.正ig…35(D)･h･w･dip.i｡･h､｡｡｡｡､､c､｡､､

Iw･id･i･･h･Aid･Sy･･1i…Th･w…1imb･･m･…b･g…1･…h｡｡｡i｡,｡｡d.h､､､､｡1imbc.m､､｡｡

be…t1･t･th･･･…亙i･･･…(A)･h･w･･i･･i････････････…Y･…,･･冊｡･･…(遇)｡･｡｡｡･i｡､

inth･｢･･t････…Mi･･k･mii･･h･Ni･趾ib･A･･i･1i…T･･w…1im･i･･…｡…h乱｡･h｡｡､､･｡｡､,

and･･m･･t･b･･…1･…h…i･･T･･㈱･1imb･･m･…b･･…1･…h･･….･･m｡｡b｡｡㎜m､.

物��畴摩�慳景��献

Thewest1imb･f･包･h舳…m･･･････…1･…h･㎞･･･････…w…1im･･…｡K.m蚊

S･nc1ine･･dth･N･･･…m･…S…1i…hi･･…1･････････…h･･｡i･｡｡…｡｡･1i･･｡島､i｡､,

thickness包･d…i…mi･･…m････…Di･･…h･w…1imb･･m…b････…｡p｡｡･i｡｡｡m｡､｡､｡｡

1a･e｢s1ike…d･t･･…d･…1･m････････････…w･i･･i･･･…(A),(D),･･d亙i｡･･…(A),(･).

周�慳琱業扣潭�瑯�来��瑯��慳琮

見ム会Interhn1bang1e

Inte｢ユimb…エ･･whi･h･･…1･･1…d血･mdi･∀･･i･ti…d･…ib･d･b･…f･h･K.m軸S｡｡c1i｡､

andtheN･m･A･ti･1i･･･…h･w･i･亙i･…31…i…m･･k･b1･･h…h･i･…1imb｡｡｡1｡､h.w､｡h､

maximum･･1･･i･･h･A･ki亙･･m･･i･…d･h･R…h…m･ti･皿w趾｡･｡･b｡｡｡h･･｡b,i｡.

一109�


S@㎡◎rd

�刮��

鮒溜榊糺婁

関0.腱

○○○

㌧

○○

○○○

○○○

○○

○○

○○○

○○○

○○○

○○○

一㌧}

6〈◎d◎m◎e甘◎O.

19刀

亙ig.37

SリzUk亘Y.◎蘭dκ◎d◎m◎K.1976

Someexperin1entsofbendingbySANF0RD(1959),K0DAMA功α1.(1974),andSUzUK-and

K0DA皿A(1976).

一110�

Fo1dsofMioceneFormationsin囲gashi-Chi㎞maDistrict,NaganoPre胎｡ture,Centra1Japan(H.蛆T0)

competent旺｡mtheir1itho由｡ies.Butinter1imbang1eshowstheminimumva1ueintheOgawaForma-

tionandtheSusobana亙｡rmation,andtheKidoMemberofthe1owestmemberoftheAok岬｡rma-

瑩潮��潦��整�畧桴瑯��整�琮

乱3A跳認亙ys量s⑫査赫醐⑰亙s奄亙幽｡在幽亜紀s

乱3｡且Ana1ysisofc1asticdiたes

The此rmationofc1asticdihesdeveloping･inthestudiedareaisa冊㏄tedbythemovementofthe

basement,and-isnota1waysre1ated-tothemajor£o1ding,jud-9ing針｡mitsmechanismoftheおrma-

tion,and-theirdistributionasdescribed1ater.Butthe砧rmationofthemareimportantontheestima-

tionofinitia1conditionsofthetectonicsysteminc1ud-ingmajor危1ding.Theauthorwantstoexp1ain

theお11owingthree血｡中saboutc1asticdi良es.First,theorigin(orthemechanism)ofthe血acturesof

�慳瑩�楫��散潮��散��潦��慣��瑯晴�摩步��物��晴�摩步��物��

Third,theageofthe此rmationofthedikcs･医UTsUzAwAandFUJITA(1967)ana1yzedc1asticdikes

deve1opedintheupperMiocene亙｡rmationwhicharedistributedinthewestwardofSendaiCity

inMiyagi乎re此｡ture.Theyproposedthatc1asticdikesarec1ass冊edintotwotypes.theyaretension

c1asticdikesandshearc1asticdikes.C1asticdikesinthestudiedareaarea1soc1ass冊edintotwotypes.

��敲瑩��潴��祥爬慮��琱��摩�捴楯湯��琱��摩�捴楯�

睨楣��搭楣由�瑯�捨潴��周��敲�晢潴��潦�慳瑩�楫�搭潮潴獨�慮�

dis1ocation.Therebre,thesec1asticdikesarein虹redtobemadeasthetension血actures,thatis,they

aretensionc1ast三｡dikes.Thesec1asticdikesdeve1opeintheupperpartofthelBessho亙｡rmation

慮摩��睥��瑯晴��歩��慴楯渮周�摩�物��楮��潮��楲散瑩潮楮�攀

��睨敲��晳��浤楮朱�敲獣�湧敲��歡�礬楮潴��獨��敲潦異�

1i丘ingb1ockssuchastheS包igawaCrushedZoneandtheCh耐Up1i舟ingZone(亙ig.21).Suchd-is-

tributionoftensionc1asticdikesasdescribedaboveprovidesthe胎aturesofup1i丘ingbasa1b1ocks

whicharethecausesoftheirbrmation.A㏄ord-ingtomanyexperimenta1workssuchasHAFNER

(1951),SAN台0RD(1950),KINUGAsA(1974),K0DAMA(1974),andSUzUKIandK0DAMA(1976)as

showninFigure37,tension舟acturesandnorma1曲u1tso㏄uronthecrestofthesur胞｡eanden1arge

theirdistributiontothesurround-ingareawhenthesinusoida1disp1acementisgiven航the1ower

boundaryofthe1ayer.Ontheotherhand,tension舟acturesorp1asticareaoccurattb,eshou1ders

�

�

～

W焔

｡､

蝦咄欝灯

1､

○

工

ω

畠

回E

F◎RMATlONS

�

灘灘鱗

､]Ikm

BASEMENT趾OCKS

鰯･[…lC･1･…1…1･･････…

珊g.38Theidea1izeddistributionofthec1asticdikesandbasementb1ocks.

一111一�


ofup1i舶ngb1oc止sanden1argetheirdistributiontothe1owerpartwhenthestepdisp1acementis

givenatthe1owerbound-aryofthe1乱yer.Thoughtheup1i舶ngmovementofthebasa1b1oc止wasnot

a1waysonedirectionandneitheronetimeexact1y,theywereformedwhentheS風igawaCrushed-

ZoneandChu6Up1i舟ingZoneup1i冊ed(Fig.38).Assomec1astic(1ikesofType1areinterrupted-by

�敵灰敲��潮��敲��潭�慶��楮慴楯��楮杰��潴�睡��晤楫��楽攀

materia1isconside･e(1tobeinjected一色rce砧11y缶｡mthe1ower1ayers.Becausesomekindsof且｡w

structuresare比undinc1asticdikes,anddikesareformed-duringthetimeofsedimentation,andunder

�散潮摩瑩潮�昱��敲慴��潦��攬�慳瑩�慴敲楡��睡�物�

ord-erto1etthem刊｡w.TheageofthebrmationofType1c1asticdikesarenear1ythesameasthetime

ofthesedimentationof1ayersasdescribed包bove,an早拮urthermore,thecoexistenceofclasticdikes

andvariouss1umpingstructuressupportsthisidea.Therefore,theageoftheirformationis旺｡mthe

depositionoftheupperpartoftheBessho亙｡rmationtothatofthe1owerpartoftheAokiFormation.

�慳瑩�楫�潦��浴潢��潴��潮�慳瑩�楫�慳��癥湯摩猱�慴楯��搭�

潦摩�献��浥�慳瑩�楫�潦��楮�牲異��睥�慮�瑯��祥��楲摩步

materia1isconsid-eredtobei勾ected一旺｡mtheupper1ayersforcefu11y.

全3.2Ana1ysisofminorb1ds

(1)Themechanismofminorお1ds

Tectonicminor£o1dsinthestudiedareaareconsideredtobebuck1ingfolds缶｡mthe£o11owing

�慓��

Minorお1dsdonotdeve1opeinmassive,thick,non-bedded,andunibrmsandstone,cog1omerate

an(1sandysha1e,inotherwords,theyexiston1yinthea1temationofsε㎜dstoneands包nd-ysha1eora

�湧��潮��敲慮��湧��湧�浥牡��祥��摩�慮�獨�攬睨楣�慶整�

慮楳潴��楮��捥�略瑯�祥物湧�

Minorお1dscometobeindistinctrapid1ytowardstheupperand1ower1ayersasshowninFigure28.

Waveshapesofminor舳dsateach1ayerarenota1waysharmonic.

Minor比1dsarenotdrag先1dsjudging血｡mtheirfeaturesanddistributions.

(2)Thepossibi1ityofminorfo1dingass㏄iatedwith㎜ajorbending比1d

Theshorteningareaofthes㏄ondaryoriginwhichresu1ted舟｡mtheup1i舶ngmovementofbasa1

b1ocたsdeve1opeinthet㏄tonicsystemsofbendingb1ding.Insuchshorteni兵garea,minorbuck1ing

b1dsmaydeve1ope,and-someminorお1dsinthestudie(1areamayhavebeen危rmedinthisway.

��數�楮��浥�浥物��敲業�瑳�慴�敎敷瑯�慮�祥爀

三sbendedbytbesimsoida1disp1acementsa伍ectedtothe1owerboundary.Theyconc1uded-thatthe

1ayershorteningdonotexceed20%,狐dthatremarkab1ebuck1ingお1dscannotd-eve1ope.

Buton1yverygent1esma11刷dsexpectedtobe此rmed-mderthisshortening吻1ue.Theauthor

hadsomeexperimentsabouttheminorお1dingwiththerotationofmajor化1d's1imbsinord･erto

studytheoriginofminor北1ds.E1asticmode1s,whichweremade缶｡ms三1iconrubbersheetsand

ge1atin-watermixture,wereusedinordertoknowthestress-straindistributionandminordeおrma-

t三〇ns.Si1iconrubbersheetsp1aythero1eofthecompetent1ayer,andthege1atin-watermixture

p1aythatoftheincompetent1ayer,resp㏄tive1y.Theweightratioge1atintowateris1:7,andthe

�楣��晳�楣潮��敲獨�瑳�敏��慮��洮周�整��搭��

beenreported(KAT0.1973).Thestraincharacterofthebendingお1disshownbytheorientationof

1ongaxesofstraine1ips〇三dsinFigure39.

一112一�

Fo1dsofMioceneFomationsinHigashi-Chiku㎜aDistrict,NaganoPre£ecture,Centr乱1Japan(H.KへT0)

玉

一

夂一

工

二､､1⊥＼/､一1〃

一へ二/二二ノ｡ぴ

��但協�汎��

＼＼/､､一

＼__145｡

Fig.39Thestraindistributioninthebending1ayerofge1atin-water狐岐ture.

TheIongaxesofstraine1ipsoidstendtobeperpendicu1artothe1ayertowardthe三nnerarcofthe

1ayerandtheirorientationarestronger尻sthe1ayerisbentprogressive1y.Thentheminorb1ds

��散��潤��潰��業敲��晴��牢�献

IntheNo.721experimentof亙igure40,thetbicknessesoftwosi1iconrubbersheetsareequa1with

eachother,that三sO.5mm.

Theimersheetbuck1es乳tthecentra1partof出e1ayer,wherethecurvatureismaximum,andthose

minorbuck1e比1dspropagatetowardthebothendsofthesheet.Butoutersheetdonotbuck1ein

�楳數�物浥��數�物浥��業敲獨�瑩��捫敲�慮��畴敲潮攬�慴楳��楣�

��潦��浥��整楳�ね��慴潦��畴敲潮��業敲獨�瑩��浥牴��

��畴敲潮�湎��敲業�琬�慴楳�整�捫��潦��浥��整楳��慴潦�攀

outeroneis1.0mm.Thoughthestraindistributionsofthesetwomode1sareverysimi1蛆,minorお1ds

搭�敬潰��業敲獨�瑯��敲業�琮周�敲�由瑳潦��敲業�瑳獵��

minorbucHefo1dsmadebythesem㏄hanismdeve1opera1e1y.Evenifitispossib互etobebrmed

minor缶1dsbythismechanisminnature,suchminor刷dsdeve1opeon1yinthecoreneartheaxia1

partwhenthe1imbsofmajorb1dsrotatedhigh1y.Thewidedistributionoftheminorお1dsinthe

studiedareaasshowninFi馴re7cannotbeexp1ainedbythismechanism,andthere危rethey

shou1dhave£ormedbythebuck1ingpro㏄ss丘rst1yexp1ained-inthischapter.

��慧��楮��摩湧

J0HNs0Nand亘0NEA(1975)examinedbuch1ingexperimentsbyusingthee1asticmode1swhichare

composedofiourphotoelasticrubbersheetsand.ge1atin1ayers.Intheirmode1s,缶ursheetsareset

-113一�

地質調査所月


��

��

�

��

��

��

�

30｡

��

〃

��

No.111�GlW畠1…7��

A.8�0･5mm�/0mm�

��

�

㈵　

40｡

��㈱

��

�

1⊆m

2.5〔m

1.5仁m

��㈱

�

村

30｡

�

35｡

珊g.40

So皿e皿｡de1慨perimentsusingsi1iconrubbersheetandge1atin-water㎜ixture,whichshow

theinitiationandpropagat三〇nofsma11fo1dsassociatedtothemajorbending{b1ding･

弱��

Fo1dsofMiocene亙｡rmationsin剛gashi-Chi友u㎜aDistrict,NaganoPre胎｡ture,Centra1Japan(H.KAT0)

tobepara11e1atinterva1sof5cm.Thethicknessofthesheets包re5,2.5,1.9and3.8cm.Whenthis

stackiscompressed1atera11y,thethimestrubbersheetbeginstobuck1eat丘rst,butthethicたestrubber

獨�瑤�湯瑢��癥��祥��潭��潮��浥瑯�癥特�牧�周�畴�爀

��浩��敲業�瑳批畳楮杳�楣潮��敲獨�瑳慮摧�慴楮�慴敲浩硴�攬慮摧潴�攀

sameresu1tthatthethimercompetent1ayerbegantobuck1eat丘rst(KAT0.1975).A免era11,in

themu1ti-1ayeredbuck1ing比1ds,.ψethimest1ayerbeginstobuck1eat趾stwiththesma11estwave-

1ength,andthethicたer1ayersbegintobuck1e1aterwith1argerwave1engths･Therebre,minorfo1(1s

whosecompetent1ayersarethimerthantboseofmajor£o1dsbegantobuck1ea1itt1e曲sterthan

��物漱摩湧��浴�楲數�物浥��畴�牢��癥��楮��楮��摩��攀

景��浩��慮��異��楯捥��

5.黎)量sc幽ss量⑱触s

5J亙冊e磁s⑬亙滅姻副細r⑧g咽瞼亙虹如s⑩亜b拙紬g⑭融逓⑰亙固量赫竜虹曲⑫秘劉融姻照亙⑱醇認g&曲⑥触

Itwi11beconsideredinthischapterthattheinitia1irregu1aritiescontro1the刷din三tiation,thatis,

the1㏄ationoftheantic1ineand/o干sync1ine,andb1dpropagation.Itisgenera11yassumedinthe

mostoftheoriesandexperimentsaboutthebuck1ingthatthereisin丘n三tedimensionhorizonta11yor

�捨�牧敲摩浥�楯�慴敲��慮��散��慶��慮搭�慴��敲楳楮楴楡�祈慴�

��牴�慢��畭�楯��祭浥�楣�慮�敲楯摩��慶��癥��業�猱��

�物��摩�捴楯測睨��楮畳��楳�楢畴楯湯晴��楳�癥�潴��睥牢��昀

thesystem.Butthisfacthasnota1waysa㏄ordancetothe£e1dobservations.Becausethethickness

ofeach1ayeroreachおrmationisnota1waysconstantasshownin亙igures3and4,andthereareini-

tia1def1ectionswhichareestimated一任｡mthedistributionofmanys1umpingstructures.Andnatura1

£o1dsdisappear1atera11ywithoneortwowave1engthseveniftheyarenotcutby由u1ts.

J0HNs0N(1969)exp1ainedthis血｡twithfo11owingthreereasons.

(1)王丑ghang1e由u1ts(正圧ETENYI,1946;BI0T,1968).

��桲畳��敢��瑤潭�物��癥��畳��夬��

��祥物�潴�慴楮�敢敧楮�湧潦��楮朮

WILLIs(1894)危undthattheinitia1dipsofbe舳ngp1anesofasequen㏄beingfo1dedcancontro1

thepositionandthere1ativegrowthsof刷ds舟｡mhisexperiments.C0BB0LD(1975)invest三gatedthe

お1d-initiationandpropagationinhisexperimentsbyusingpara伍nwaxwhichisgivenbe11-shaped

initia1disturbance.亙romhisexperiments,wavesbecometoberegu1arwhentheshorteningismore

than15%whentheviscosityratiois10.亙romSKJERNAc(1975),regu1arwavesdonotdeve1opewhen

��牴�楮�猱�楮��楳�畳�捫�數�物浥��湧��慳瑩捥��桷��

periodicityoHo1dsdescribed.aboveisconsidered.toberesu1ted趾｡mthe缶11owingnatura1conditions;

5｡且.夏Irregu1aritiesinsedimentaryrocks

Co朋0LD(1975)poi皿tedoutthattherearesedimentary1enseandnodu1easgeo1ogicinitia1d.e且ec-

tions.Theseirregu1aritiesareenoughtoinitiateminorお1dsofwhichwave1engthsaresma11er出ana

此wmeters.Exceptsuch1enseandmdu1e,initia1disturbancesof1ayeringsuchassomekindsofs1ump-

楮杓��卡��敲��

則･2Non-tgctonicdepression包nd/orcu1mination(raisedpart)duringdeposition

一115一�


TheNomaAntic1inea㏄ompaniedwithminor£o1dsisthetypica1examp1eofthisasshownin刑g-

ure9.Directionsofd-ipsofthese胎1dsa㏄ord-most1ywiththoseoftheforsetbe(1sofcrossbed-dings.

�摩�捴楯湯晴��浤�潦�敦��瑢�獨��牲�瑤楲散瑩潮慴�灯�瑩潮��楲

di正ectionpointsoutthattherearesomenon-tectonicdepressionand/ortheraised-partnearthe

�楡��瑳潦��敦漱��潴��牲敧由�楴��晢��瑩��捴楯�慴�灯�瑩潮��

contro1thed-epositionoffo1ds(noton1ymajorfo1dsbutmimrお1ds).Furthermore.asthedistribution

ofcrossbeddingsa㏄ord-swiththatofminorfo1〔1s,theseinitia1irregu1aritiesmaycontro1thedeve1op-

ementofminorfo1(1s(especia11ytheirpropagationtotheaxia1direction)｣T0(1976)reportedthe

sameinitiationabouttheNanakuraAntic1inenearFutatsuiinAたitaPre危｡ture.Hepointedoutthat

theaxisoftheantic1ineaccor(1stothe1ineofthemaximumup1i舳ngofthebasewhichisdeduced

缶｡mthedistributionofcrossbed中ngsand-thechangeofthe1itho血｡ies.

5.且.3Thethicknesschangeof1ayers

Thethic良nessch乱ngeof1imbsoftheNishikibeAntic1ineintheBesshoEormation三sthetypica1

examp1eofthisasshownin亙igure4.Thesimi1archangeofthic良nessarea1soobserved-intheAoki

Eormation,especia11yintheKi(1oMember,whichisthe1owestpartoftheAoki正｡rmation,asde-

scribedinthepre袖｡ussection.KAwAUcHI(1973)andKAsAHARA(1973)reportedthatthicknessof

theOgawaFormationandtheAo蜴亙｡rmationarethethinnestattheaxia1partoftheNomaAnti-

�楮��慴�整�捫��潦�敷�琱業��桴�捫敲�慮�慴潦��慳瑯��慵��

studysupportstheirthoughtsthatthechangeofthethickness1ocatesnearthe£o1dingaxis,The

simi1arsituationsexistinmanycases,おrexamp1e,theAidaSync1ineandtheKomOiSync1ineasshown

inEigure41.亙ur{hermore,the1itho曲｡iesandthethicknessofe乱｡hstratachangeneartheaxia1part,

��捩��楮��瑩潮�

TAKEUcHIand-SAKAM0T0(1976)a1soreportedthatthethicknessoftheAoki正｡rmationinthewest

1imboftheSaigawaAntic1inewhichwasname1ytheNodairaAntic1ine,w釘s丘vetimesasthick

asthatoftheeast1imb.Thethicknessoftheeast1imbisa1so(1i冊erent缶｡mthatofthewestoneinthe

肪ka趾Sync1ineandintheHikageAntic1ineinthenorthem亙｡ssaMagna.Thehingesofm乱jor

お1dsdistributeinthestudied-area1ocateatthep1acewherethethicknessand1ithofaciesofnot

on1ybrmationsbuteachsing1e1ayerchange.Thisfactmeansthat先1dsinitiateatthebomdaryof

thedi伍erentia1depression,andinitia1wave1engthsarecontro1ed-byinitia1irrggu1aritiesatthebegin-

ningof刷ding.Thereおre,underWi11is,sconditions,muchdあrmedb1dscandeve1opeevenwh㎝

��牴�楮杯晴��楳�楴��慮�┩�

52丁臨e醐e砥盈赫s㎜⑬歪醐勾鮒窃⑧蝸s

Fourideashavebeenproposedaboutthe£o1dingmechanisminthenorthem亙｡ssaMagnaarea,

��攻

(1)Simp1ebuck1ingわ1dsbythe1atera1compression伍｡mthenorthwestorthewestofthe

��条睡��散瑯�捌楮�

T0MIzAwA(1953)surveyedtheNishikyo-KamikusugawaAntic1ine尻1ongSusobamRiverinthe

westwardofNaganoCity.Hewasoftheopinionthαttheお1d-iscaused-bytheshearstresswhich

pointstothesouthwest缶｡mthenortheast.亘egaveevidencesthatthe£o1dhavetheasymmetrica1

andinc1inated胎ature,theeast1量mbisverysteep,part1yovertumedwhereasthewestoneisgent1e,

andthatthevertica1血u1twithcrushedzoneintheaxiaIpartistransおrmed-tothethrust.Hea1so

一116一�

Fo1dsofMioceneFormationsinHigashi-Chiku㎜aDistrict,NaganoPr哉ecture,Centra1Japan(亙･KAT0)

reportedthesame飴atureabouttheSaigawaAntic1ineinthemidstreamdrainagebasinofSaiRiver･

Tomizawa,smode1isthatthehorizonta11ayersintheinitia1stageof北1dingbythe1atera1compres-

sion血｡mthenorthwest.Hecannotexp1ain,however,thatthethicker1imbissteeperthanthe

thinnerone,andtheoriginoftheextema1おrcewhichcausedthe1argeshortening(30-40%)and

thecompatibi1ityofthestraininthisarea.Suzuヒi(1974)deniedsuch1atera1compression趾｡mthe

westand伍｡mtheIeastasthemaincauseofbIding,Hepointedoutthatthegeo1ogicstructuresof

�牴楡特景�慴楯�楮��慢整睥��慣��慮搭�步�歩�敧�琱��

areperpendicu1arorob1iquetothetrendofthenorthern亙｡ssaMagna,andthatha1fd-omeand

basinstructurestrendtothenorth血｡mthesouth.

(2)Theben(1ing£o1ds(ortheb1ockfo1ding)ofcover1ayersbythedi伍erentia1b1ockmovements

潦�敢慳��琮

SUzUKI(1974)saidthatfo1dsinthisareaarecombshaped£o1dsbe1ongingtotheintermittent

先1dc1assifiedbyB肌｡Ussov(1954).Hisexp1包nationaboutthe缶1dingmechanisminthisareaisthat

�敢慳��瑩��步��敲��歳慮��歳浯癥�灯��慣��敲�

Heconsideredthatthehorizonta1bedsatse(1imentationare1engthened-whentheb1㏄ksmoved

downandtheyhavetobe£o1d-edwhen.theb1ocksmovedup.亘esuggestedthatthemudstoneof

theBesshoFormationc乱ni句ectintothestressconcentrated-partsneartheboundariesofthese

��歳�

Hegaveevidencesthat,a丹erthedepositionoftheOgawa亙｡rmationinthewestemareaofthe

卡�慷��楣��潭��整��潦楴�畴�数��摩�物�瑩潮

ofbedsshowsthe丘na1d-ownmove㎜entoftheeastemareaand-thattheSaigawaAntic1ine1ocates

insuchhingepartsofdi脆rentia1upordownmovement.A㏄ordingtoSAKAIθ～ム(1976),mmerica1

experimentsbyusing丘nitee1ementmethod-showsthatわ1dsdeve1opeintheboundarybetweenthe

mobi1ebasementandthe丘xe(1one｡且｡wever,suchb1dsareverygent1eandthier企aturesaresinusoi-

da1.Thereおre,theirresu1tsdonotagreetothem㏄hanismofnatura1b1dseventhougheachparam-

etersofexperiments乱rechanged.Suz止i,sid-e包isgeo1ogica11yweaたbecausethedi冊erentia1movement

ofbasementsbegins血｡mthedepositionatstageoftheAoki亙｡rmationat1east,and-becausethe

corre1ationoftheOgawa亙｡rmationindi伍erentbasins,thatisinTaka㎞and.Komiji遍asinsisnota1-

wayssu冊｡ient.Anda11minor刷(1sarenota1waysmadebytheinjectionofmudstoneresu1ted舟｡m

theupordownmovementsofthebasementsasSuzuたisays.Onthecontrary,mostofm三norfo1ds

�敲�慴�瑯��景�楮条��捲楢�楮�数�癩��散瑩潮�畴��畧来�楯�獰�琱��

rect,thatis,thehingesoffo1ds1ocateatthechangingPointsofthethicknesscausedbythedi伍erentia1

depositionbefore£o1ding.

(3)Akindofthedragfo1dsassociatedwithwrench血u1ts.

��味��睥��来潭整物��畳�慴楯��畴�数慴�浯晣潭��潮��捥�

睨楣��摩��牴潴��搭��獵��獰慴��楴桴��

pattemofwrench由u1ts･According亙UJITA(1975),aユ｡ngtheItoigawa-ShizuokaTectonicLine,

the比1dingaxesarepara11e1tothis1inea.nd-theyareob1iquetoitintheNiigataArea.Theiraxes

pattemre且ectstheaxisofsedim6ntarybasins,butt㏄tonicmovements.Mo0DYandHILL(1956)

suggestthesecon(1arystress丘e1dassociatedwiththemajorprimary由u1t,andthatinsuchstress五e1d,

akin(1of(1rag舳dsbywrench鼠u1tsmaybepossib1etobebrmed.However,eveniftheirid-eaiscor-

rect,on1yoneortwowave1engths缶1dscanbeおrmedbysuchmechanism.

一117�


(第30巻

第2号)

イ､

■整韓…………姜……

�ね

レ窓ぐ､

井1･塾轟_竃蓑……美嚢菱嚢..

�ね

�ね

/'へ､

■■^＼＼

�ね

5い

､､＼ノ〃･ク､･､

1……姜葬

;……………舌…;葦………≡吉'一

�ね

1川

��

�ね

��

llll■

.､･一500m

lllll,■■

�朮�

��散瑩潮献

�ね

∴m

We11-deve1opedあ1dsinthenorthem亙｡ssaMagnacannotbeexp1ainedbysuchm㏄hanismquan-

瑩�瑩��

(4)Akindofthebuck1ingb1dbythecompressionob1iquetothe1ayeringwhichisre1atedおr

��搭��浥��

UE㎜趾(1971)consideredthatovertumedお1ds三nMt.KushigatainthenorthemNiigataPre胎｡一

弱��

Fo1dsofMiocene亙｡mationsin囲gashi-Chi㎞㎜aDistrict,Nagano趾e島｡ture,Centra1Japan(H.KAT0)

��睥�景��瑩湧��瑩潮�

亘esuggestedthatitwaspossibIetointerpretmostp1ob1emsbfb1dingmechanismattheup1i冊ng

��湫楮杢��瑩湧潦�敢慳��敲��慴敲��楯渮周�畴��異灯牴��愀

principa11y.butonmanyprob1emssuchastheconditionof1atera1compression.mtura1evid-en㏄s

��瑩��楲��

Themechanismofthese危Idsinthestudiedareaisthatthecoversedimentswhichhaveinitia1

waWbrmscontro1edbythed冊erentia1sinkingmo∀ementsofthebasementattheirdepositiona1

stage,isbuck1edandamp1i丘edbythesecondary1atera1compressionduetotheup雌ingofthe

Saigaw乱CrushedZoneandtheCentra1ZoneofUp1i冊ing(Ch脆Up1i舳ngZone).Initia1de且ections

suchasthed捌erenceofthethicknessand一/orthesurfaceirregura1itiesofthebasementareactedas

��来�潦景��湧�

Thecauseofextema1forceistheti1tingofthebasa1b1ocksanditmoves舟｡mthesouthtothe

north.Thereasonsasdescribedabo∀ewi11besumarizedasお11ows.

(1)Inthebuck1ingお1ds,theamp1itude-wave1engthratioand-themeanshorteningareexpected

瑯獨��業畭癡��牡瑩杲慰��潦�散潭��祥�楴��牡瑩杲慰��

sectionsandinter1imbang1eshowstheminimumva1ueatits1eve1asshownin亙igure30.Inthebend一一

ing危1ds,theamp1itude-wave1engthratioandthemeanshorteningareexpectedtobesma11erand-

inter1imbang1eis1argertowardtheupper1eve1asshownin亙igure29.IntheKom軸Sync1ineand

theNomaAntic1ine,theamp1itude-wave1engthratioandthemeanshorteninghavethe平aximum

va1ue,andtheinter1imbang1ehasthemin三mumva1ueattheOgawaandtheSusobana亙｡rm風tions

andattheKidoMember.Thesemembersarejudgedtobecompetentlayersorcompetentmits血｡m

their1itho1ogica1勉｡ies.

Thereおre,thosemorpho1ogica1charactersaretobeconsistentwiththoseofbuck1ing刷ds.

(2)A㏄ordingtothemmerica1experimentsofbendingio1dsbyIKEDAandSHIMAM0T0(1974),

��業畭��敲瑩��捲�瑯晴�慮瑩�楮攬慮��票��潮��

楮�散��晴�慮瑩�楮��摩�物�瑩潮潦��潮��潭��潮楳��物捴��

anditdisappearsastheincreaseoftheshortening.IntheimerarcsoftheNomaA■tichneminor

曲1dsbybuck1ingwe11-deve1opeinspiteof1argeshortening.Thereおre,itsstress-strainimageisnot

thatofbendingfo1dsbutequa1tothatofbuck1ing£o1ds.

(3)Inthewest1imboftheKom軸Sync1ine,theaxesofminorb1dswhichdeve1opedintheAoki

亙｡rmationa1ongAidaRiverarenotconcordantwiththose(1eve1opedintheupperpartoftheBessho

亙｡rmation,andinthe1owerpartoftheAoki亙｡rmationa1ongtherouteofNagamine.Thatis,inthe

捲��散瑩潮��楮��楳��獵�敲��楣��獵捨摩獨�浯�捷慶��數楳�

楮��由瑩��敲��捥��楳��潮楣睡癥獣慮�獨��潭��祥�

ofwhichthethicknessared冊erentareiso1atedeachothermoderate1y,thatis,thedistancebetween

��整�琱�敲��浯��慮潮��散��慶��由瑩��敲��捥��

1atera1y(RAMBERGandSTEpHANss0N,1964;HARAヨ1967;RAMBERGandSTR0MGRAID,1971;KAT0.

1975).Suchdisharmonicwavesme包ntobemadeby1ayer-para11e1compression.Inmajorfo1ding

��癥��摭楮�景��楣慴整�搭潭楮慴��慴敲��楯��瑩浥潦浩湯爀

缶1dingat1east.Inotherwords,theminor刷dingareaisthecompressionarea.Thisideasupports

�慴��牢��捫�湧景�献

(4)S1ic止ensid,es1ikesIipsobservedinthemassivesandstoneandcong1omeraterocksoftheOgawa

一119一�


㌻

＼

■

'＼

�

､

一

て

吻

�

すメｰ

→一

6て

､トト

､ノ＼)…

･､

･〃･'1

一

＼1

ノ

ノ

ノ

�

l､.㌧/∵〆

ニギニ“lll㌻ぺ

r薯∴.ジ

■ミ､/･一

1･シ■･炉

〃〃

一

一/

･･…ノ戸ぺ･//

㌃XA.H･'

/＼'/'･''1ポ

､!//

/'工!

�

�

Sf･ik･一f･･q……γdb9･㎝fα

E一■1eoxe50fn､■nor吾｡■d5

�

Fig.42Thetectonicstress丘e1dinthestudiedarea.

30完E

�攵�攀

��昀

潤晥

廿.di◎1.ife

o[Phy了ite

･･phy.dik･〕

ぺ

回榔催涙､

国8織n冒｡絆

囚A･kiF･1m･

[亘コB…h･r･m･

moximum一{infermediof8〕

廿…i1･p･i･oipo■･打e･･

＼1■辮鮒

��

亙｡rmationa1ongOmiRiverareHexura1onesa㏄ompanie(1withfo1d-ingassuggestedbyMIzU岬｡

(1976).Theses1i台sareapttobemadeinbuck1ingprocess.

(5)IftheKom巧iSync1ineandtheNomaAntic1inearebucHed此1ds此rmedbythe1atera1com-

pression,thetensiona1movementsmustbed-ominantintheouterarea.The£actthatminorreverse

由u1tsarerestrictedinthe先1dingareasatis丘esat1eastthestraincomp航ibi1itycondition.

Itwi11beconsideredthetectonicstress丘e1dinthestudiedarea.Thehistogramoftheaxestrends

ofminorb1dsinthestudied一包reainthewestoftheMatsumoto-NaganoLineisshowninEigure42.

Strike一舟equencydiagramfortheaxesofminor缶1dsshowsthatthetrendsaremost1yN_S,andthat

theyarepara11e1toaxesofmajor比1ds.Whenbothmajorandminor比1dsare£omedbybuck1ing

asd.escribed-above,thep1anema〔1ebythemaximumtensi1eprincipa1stressandtheintermediate

�楮捩��獰��潴�景��慳獨��楮��業畭��攀

principa1stressisperpendicu1artothemasshownbydotted-1inein亙igure42.This.stresscondition

contimedat1east舟｡mmidd-1eMiocenetotheuppermostMiocene.Thehistogramofstriたesof

porphyritedikesdistributedintheeastoftheMatsumoto-NaganoLineisa1soshownin亙igure42.

周��摎�南��慮��敢��楮��楡��楮捩��業畭��

��癥�楮捩��獰��潴��物步潦摩步�慮搭��業畭��数物��楳

norma1tothem缶｡mthemechanismofthebrmationofvo1canicdikes.

Thoughtheirintrusivestageisbe1ievednottobeon1yonce,thestresscondi亨｡ndescribedabove

-120一�

亙｡1dsofMiocene亙｡rmati㎝sin貫igashi-Chiku如aDistrict,NaganoPre胎｡ture,CentralJapan(H.KAT0)

r卜τ3

漬㌀

^1一^2

1''､､

1[1'一!＼

1一一'{'コ.＼'

�

''■一一一一'■一■一■一'■一一■一一X

～｡｡｡1､､晒､柵､皿､旧11111～

醸嚢OO州NErO舳AτlON回OGAWArO洲ATlONロコAOKlrOR舳τlON皿酊BESSHOrO舳ATlON

亙ig.4写Thecrosssectionofthetectonicstress丘e1dinthestudiedarea.

showsthemaximumtensi1eprinc三p邑1stressand/ortheintermediateprincipa1stress.

showsthem乱ximumcompressivepr三ncip町1stressandlortheint6rmediateprincipalst陀ss.

contimedat1east舟｡mmidd1eMiocenetoupperMio㏄neastheirstrikesareconstant1yNE_SW.

Thestressconditiond-erived伍｡mconjugatenorma1minorfau1tsinthisareaisconcordantwiththat

舟｡mporphyritedikes.

囲gure43showsthecrosssectionacrosstheX-XinEigure42.

Themaximumcompressiveprincipa1stress三shorizonta1intheお1dedareaandthemaximum

t㎝si1eprincipa1stressishorizonta1innon一比1dedarea.Whatconditi㎝doesmakethisstressdis-

tributionpossib1eHtwi1Ibediscussed-andcomparedwiththeresu1t舟｡mmmerica1experiments

byusing丘nitee1ementmethodandtheresu1t旺｡mgeo1ogica1investigation.Thestressdistributionin

thecover1ayerwhentheb1ock-shapedup1i舳ngdisp1a㏄mentisgivenatthebasement,isgotby

using丘nitee1ementmetho(1.Inthismmerica1experimentbyKINUGAsA(1974)､theb11owingsimu-

�瑩潮��畳��數�物浥��楴楯��攬湯��昱��畭��潦㈹��本�

浯��生洲��潦㈮�生洳��潮�牡瑩潯��慮��摩浥�楯�潤�

潦��

ThoughYoung'smodu1usistoosmaI1erthanthenatura1one,itissu冊｡ienttoshowthestressdis-

�楢畴楯渮周�潴��楮敲数��漱��獨��

respective1y(亙ig.44).Thisresu1tisfair1yconcordantwithtahtofEigure43.Therefore,at1east,these

b1dspanbeinterpretedtobebuck1ingお1dsbythesecondary1atera1compressionass㏄iatedwith

theup1i舳ngofbasementb1ocksqua1itative1y.Thoughthequantitativeinvestigationisverydi舶｡u1t

慴��業攬楴��獨��潭数��敲�整慴楯�慳景��献��敷��慯昀

ChikumaRiver,thethicknessoftheBessho正｡rmationand.theAoki亙｡rmation,esp㏄ia11ytheKid0

��敲捨慮来��慢��潮��瑳畭潴��条湯��晴��獨楫楢攀

Antic1ine(亙igs.4and7).There1ationsbetweenthechangeinthicknessand-inaxesoffo1dsand

thed冊erenceinthicknessbetweenboth1imbsarewe11known.Itisa1soknownthatnon-t㏄tonic

disturbanceofthesur血｡eofthebasementin此rred血｡mthecrossbed出ngandothersedimentary

structuresactedasthetriggerofb1dinginiti含tion.Thesefactsshowthatnatura1お1dsarenotresu1ted､

舟｡mde缶rmationsofHatp1atesintheinitia1stageasmostgeo1ogistsassumed-intheirtheoretica1

andexperimenta1works,andthat1ayersha∀einitia1de刊ectionsatthei㎡tiation.玉nthee1asticmode1

experiments(KAT0.1975),theinitia1waveo㏄ursattheinitia1disturbanceofsi1iconrubbersheet

一121一�

筐蝿蟄塒ヨ辻難(癖｡｡o瞭隷心噂〉

ド

�

〕!__■._.､▽_｣ZLL

〆¢レヘヘ

〆庚ヘヘヘ､N､てマ7ク

4〆～

へ｢▽▽▽▽∀▽▽'▽▽

�

!㌧㌧戸戸戸戸戸777､

､

､♪

一ノμφ4ノノ戸戸戸クヘ

ダｰ4｣一4}

＼､､一

＼＼＼＼､

､1

ムヂｰ企'..

�

･'

�

米

ニニ

ん

■･

ん

/■■､

ノ

㌦ソ/亡

､､1,⊥1■1､

､{､

＼＼

､＼

＼＼､L↑､､

､へ＼

＼＼t+

＼＼､“､上､

＼＼斗十一

･＼＼へ

＼キ'十

｡･^Ψ

人一

メ''小∴

一'､一

×一

..､｡■､ソ＼∵

//ン∴

/一

･沙

/､＼穫

-〇一

､/

.､

､

.■一,徽･万

点窺葦

←Z山r｣山O江｣しωH0

居

心

○∩

⊂∩

し⊥｣

虻

ト

⊂n

｣一

�

し

(｣

乙

Qケ

�

2000孔O只G/C門*キ2CO門PRESSJVE

･ト1･…1･･

2000..0K』/CN**2↑ENS1LE

Fig.仏A…㎜p1･･fm㎜･･i･･1･･p･･i㎜…,whi･h･･p1･i…h･･t･…di･t･ib･･i㎝･h･w･i･亙ig･43

(A肚erKINUGAsA,1974)･�

亙｡1dsofMiocene亙｡r独ationsinHigashi-ChikumaDistrict,NaganoΨrefecture,Centra1Japan(H｡阻T0)

睨楣��浥��楮杯晴��湲畢��整楮瑯�敧�慴楮��楸��牡��

ThesamefacthasshowninWi11is'sandCobbo1d,sexperim㎝tsasdescribedprevious1y.Itisimportant

楮��敲業�瑳�慴�牧��景�慴楯��数��敵�敲�散潮摩瑩潮潦��牴�楮木��

than10%),if1ayershaveinitia1de且ections.Andsuchsma111ateralshorteningmaybepossib1ebythe

causingup1i冊｡fbasa1b1ocks.亙urthermore,bytheAidaFau1tand-theNanatsumatsuFau1t,the

��潦�敍慴獵浯瑯�慧慮��獵�潴�睥��慮朱��慴

�敷��愨�敦漱��楳獵�散��潭��潮��獵灰�瑳��捲楢�

慢��

5･3亙⑥亙副量醜g虹量sヰ⑪亙y

First,itwi11beconsidered包boutthepre-tectonicstage(thatis,pre-fo1dingstage),name1ysedimenta-

tionoffo1d一拓rmingstrat包andthe£eaturesofsedimentarybasinswhichcontro1edtheinitia1con-

ditionsofお1dingandthemovementsofthebase.

TheigneousactivityofGreentu任vo1canicrocksoftheUchimura亙｡rmation,whichon1ydis-

�楢畴�楮��牴楮��摩��潭整��楮浩��業畭

transgressionoftheseawhichisrepresentedbythesedimentationoftheb1ac止sha1eoftheBessho

亙｡rmation,beg包n.Theorientationofthesedimentarybasinwhichcon‡ro1edthedepositionof

theUchimuraand-theBessho亙｡rmationsisveryimportant.

Wehavetwodi伍erentopinions危rthis.TheonewasproposedbyT0MIzAwA(1953).Hesaidthat

theboundarybetweentheUchimuraandtheBessho亙｡rmationstrends皿一Wandthatitsboundary

楳��慴��浯潴栬睨�整��浤�祢整睥��獨��歩��慴楯�楳�捨

indented.Theotheropini㎝wasproposedbyMARUI(1972)and/or肺JITA(1973),anditisthatthe

orientationofthebasintrendN-S.Maruisaid-thattheGreen.tu任rocksareinter丘ngeredwiththe

tu旺aceousmudstoneoftheUchimura亙｡rmation,thatthesediment孤yrocksdominatestothewest,

thattheBesshoEormationincreasesitsthicknesstothewest,andthat比1dらintheUchimura,Bessho

andAoki亙｡rmationsp1mgetoN_Eandd-onota品ecttheupperformation.Fujitasaid-thatお1ding

axestrendN-S,thatintrusivedikestrendN-SヨtooattheGreentu旺movement,andthatthese虹｡ts

suggesttheorientationof血acturingattheinitiationofthesed-imentarybasin.Inordertodetermine

theorientationofthebasin,theisopackmapmustbedrawnandcomparedwitheachdistance旺｡㎜

thethicたestpart,thatis,thecenterofthebas三ntothemarginofthebasin.

Unbrtunate1y,theBessho亙｡rmationismost1ycoveredwiththeupperformationsinthenorthem

area.Therefore,theexactdistributionofthethicknessoftheBessho亙｡rmationinthenorthemarea

1snotmknowntous,yet.IntheE_Wcrosssectionin刑gure4,thethicknessoftheBesshoFoma-

tiond-ecreasesitsthic良ness舟｡mHo趾しuOitoChikumaRiver.IntheN_ScrosssectioninFigure4,it

楮捲��瑳�楣歉��瑯��慮��慴獵獨楲漬�慴楳��整��

Thisfactmeansthatthere1ativeup1i丑｡fthebasementisat1eastmoreremarkabIetothesouth,and-

thatthesedimentarybasinbegantobedi伍erentiated-bytheup1i冊ngbe1twhichtrendsN-S,orN瓦一

SW,atthetimeofthesedimentationoftheBesshoForm包tion.Thisup1i丑ingoccured㎝1yinthe

��浥瑯��慢�慴��慴敲�慧�晴��慴楯��摩浥�慴楯渮

Th三sup1i舟ingisamain曲｡torcausedc1asticdikesanddeci(1edtheshapeoftheup1i舟ingbasements

Iooks1ikeb1ock.Bythisup1i舳ng,apartoftheareawheretheBesshoandtheUchimura亙｡rmations

distributed-tumedtobethe1a.ndandthenwaseroded.Thee切dencesofthis由｡tarethatthereare

一123一�


bre㏄iaand/orcong1omerateoftheGreentu旺rocksderived一缶｡mtheUchimura亙｡rmation,a1tered-

andesite,basa1tandbre㏄iaofb1acksha1ederived杜｡mtheBessho亙｡rmationintheuppermosts乱nd一一

stoneoftheBesshoFormationand-theKidoMemberwhichisthebas包1partoftheAokiFormation.

亙urthermore,theigneousactivityassociatedwiththisup1i丑ingisknown.Qμartz-dioritegrave1s

��楴��摯��敲�散��潴��楯物��捫��啣��牡��

accordingtoII〕IMAandSAIT0(1968).Theyconsid-eredthatquartz-dioritehad-intrudedbeforethe

sedimentationoftheAoki亙｡rmationwiththeup1i舳ngareawheretheGreentu任distributed.Ko-

BAYAsHIθ～1.(1957)proposed``theBesshoPhaseMovement".Theyconsidere(1thatthemostof

porphyritic(1ikespenetratedintotheHong6亙｡rmation(apartoftheUchimuraFormation)and-

theBessho亙｡rmationduring£o1dingoftheNishikibeAntic1inean(1soon,becausethesedikescon-

centrateintheaxia1areasofantic1三nes,andquartz-dioriteintrudedintothereduringthe丘na1stage

ofthesed-imentationoftheBessho亙｡rmationintheprocessoftheGreentu任movement£romthe

reasonsofthechangeinthesedimentaryenvironmentsandtheup1i冊ngofthehinter1and-The

慵��摯�湯��瑳��批��捥��數楳��潦�攀

up1i冊ingpart,quartz-dioritegrave1s,c1asticdikes,andmanysortsofs1umpingstructures,the

distributionofb1acksha1ebrecciaderived丘｡mtheBessho亙｡rmation,thechangein1itho1ogyand.

thicknessesintheuppermostpartofthe週essho亙｡mationandintheKidoMember,andtheigneous

intrusionduringthe(1eve1opmentoftheNishikibeA耐ic1ineandtheKinokoyadaniSync1ine.But

��畴�牢��癥��瑩獲慴��潭�潮��慴楴�捴�楴��

becausethatthedistributionofgrave1sderived舟｡mtheUchimur乱andtheBessho互｡rmationsis

�浩�摩湶敲��睡�愬��楯物�杲慶��楴礬�慴猱畭�湧�浣��

��獲��歡�整��睥��潦�敍慴獵浯瑯�慧慮�楮攬�慴��獲�歳�搭

intrudeda冊erthesedimentationoftheBessho亙｡rmationbuttheirexactstagesaremcertain,and

thatthe£o1dingisveryweak.

Next,itwi11bediscussedaboutthestudied-areawheretheBessho1Formationdistributes.TANA蛆

(1958)pointed-outthattheNishikibeAntic1ined-eわrmed舟｡mtheHong6Eorm乱tiontothe1owest

partoftheAoki亙｡rmation,butthattheirde£ormationdisappeared-rapid1ytotheupperpartofthe

Aoki亙｡rmationandthatthebasa1cong1omerateoftheAoki正｡rmationinc1udedtheGreentu旺

grave1s.Heconsideredthatthisantic1inewasmadebytheBesshoPhasemovρment.Theauthora1so

be1ievesthattheNishikibeAntic1ineandtheKinokoyadaniSync1ineare趾ndamentarybucHing

お1dsinthemidd1eMioceneandthatthecompetentunitistheKidoMember.These捌dsinitiated

ear1ierthanthoseinthewestareaoftheMatsumoto-N勧ganoLine.Minorfo1dsinthisareaare

��敲�瑯��批�效�慧�晴��歩��楮楴楡��来潦��摩湧潦

theBesshoPhaseMovement旺｡meviden㏄ssuchastheirweakdeおrmation.imegu1aritiesoftheir

axestrendsandthemechanica1propertiesofrocks.TheSaigawαCrushed-Zonebegantoup1i冊旺｡m

thesouthempartsincethe£na1stageofthesedimentationoftheBesshoFormation舟｡mthedis-

tributionofc1asticdikes,s1umpstructuresandb1acksha1ebr㏄cias.Thoughthisareadid-notemerge

abovesea1eve1.itsa伍ecttothesedimentaryenvironmentswasremarkab1e批erthe1aterstageofthe

�摩浥�慴楯湯晴��歩��瑩潮�楯捥��摩浥��祢慳楮睡��楮瑯��慳瑯�慮�

thewestonebytheCh脆Up雌ingZoneintheperiodbetweenthe£na1stageoftheAoki亙｡rma-

瑩潮��睥��摩浥��祢慳楮��潰�楮��慴敲�慧整��攀

westemsedimentarybasinisdi伍erentiated-intosomesubbasinsbytheMatsumoto-NaganoLine

-124一�

Fo1dsofMi･･e･･亙･･岨･ti…虹囲…hi-Chik㎜･Di…i…N･･乳･･P･･胎･･…,C･･…1J･｡･･(H.K｡｡｡)

･･d･h･S･ig･w･Cm･h･dZ･…Th･A･炎i亙･㎜･･i･･i…m-p…d･f･h｡｡1･｡m｡｡i｡｡｡f｡｡｡d｡｡｡｡｡

･nd･･ndymud･t㎝･,･･ng1･m…t･,･･nd･t㎝･･ndmud.t.n.with｡｡｡1｡｡｡m｡.

N･m･工y･･h…mp･･i･i…f･h･A･ki亙･㎜･ti㎝1･…㎎…h…h…f･h｡遍｡｡｡h｡亙｡㎜｡｡i｡｡.Thi.

f･･tm･･…h…h…dim･･…y･･由㎝m･…f･h･A･ki亙･･m･･i…｡m.d･｡･h｡｡h.n.w｡｡｡｡｡d

thatth･b･…fth･b･･i･1i冊･d･丘…h･皿…h･亙･･㎜･･i･･d･p･･it･d.M･･｡･･･…f･1･mpi.g｡･｡｡c.

tureswereおrmed-mdertheaboveen柏ronmentsandthesinking五nthebasindi胎rentiatedsti11more.

Th…th･thi･k･･…f･h･A･ki亙･･m･･i…h･･g･di･･h･h･･i…t･1di･…i･･.Th…i｡｡｡g｡｡｡1i･i､､

i･iti…dm…1ymi…比1di･gb･･的･･舳i･g･･d･…ib･di･･h･p…i｡｡｡｡｡｡｡i｡｡.Th｡｡｡i｡｡｡｡.

ti…fth…dim･･･…b･･i･･f･h･A･kiE･m･･i･･wi11b･･…id…d伎･㎜･h･･h｡｡g.i｡｡hick｡｡｡､.

Th･1i…fth･m脳im･mthi･k･…p･･…f･h･A･胴･m･･i･･伍･m･h･w･…fAid｡･｡K.d.ki,

��中�

Th･di臨･…i･･i･･i･･h･w･…mb･･i･b…m…b…m･･k･b1･･免…h･1･･…｡g｡｡f･h.A｡拙

㌃rテ

､

㌀

＼㌔A

にOMI｣lFSuSOBANA『.

一榊“

佇��

A◎1〈lF､

ll口

!'､､

･'…一'一'一一概鞭埼

5r封〆)ザ､､､､三一一!一き

}∵＼∵

1皿叱､.一

1一'

Fig･45F･1dinghi･t･･y.

一125一�


��慴楯測慮��楮略�潴��慷慓�来��卡�慷��慷�捨楳��牴�敷��

marginofthesedimentarybasinoftheAoh亙｡rmation,thereisa1soaboundaryofthesedimentation

睨楣��瑯�敍慴獵浯瑯�慧慮�楮攬�慴楳��卡�慷慄楳�牢��潰��批

SAI鮎wAREsEARcHGR0UP(1966).TheSaigawaCrushedZoneisapartofthis(1isturbedzone.The

up1i冊ngofthiszonebegan血｡mthe丘naIstageoftheBesshoEormationwhenitinitiatestheNodaira

AnticIine.Astheseup1i冊ingscausethe1atera1secondarycompression,someminorfo1dsintheAoki

亙｡rmationhavethepossibi1ityofinitiationattheendoftheAokiStageoratthebegin口ingofthe

OgawaStage･Igneousactivityismost1yrestrictedintheeastareaoftheMatsumoto-NaganoLine.

TheOgawa亙｡rmationismost1ycomposedofmassivesandstoneandcong1omeratewith05桁θα缶ssi1

beds,coa1seamsandso㎜ekindsofsedimentarystructures舟equent1y.Its1itho由｡iesshowsthat

thesedimentaryenvironmentoftheOgawa亙｡rmationbecomestobesha11owerthanthatofthe

�歩��慴楯渮周��業畭�楣��晴��慷��瑩潮楳浯��慮�〰ね��卡獨�

kiriintheeast1imboftheKom軸SyncIine,butitreaches500t0600mintheeastareaoftheMatsu-

浯瑯�慧慮�楮�周�物��瑩潮潦��業��特��湯晴��慷��瑩潮��也匀

aswe11asthatoftheAokiB刎in.AndtheOgawaBasinisdi衝erentiatedbytheMatsumoto-Nagan0

Line.Thesedi舐erentiationcontinued舟｡mtheAokiStage.TheSaigawaCrushedZoneandthearea

betweentheaxisoftheNomaAntic1ineandtheM風tsumoto-NaganoLinetumedtotheremarkab1e

牡楳��牴献周�敲��瑳慮��楮歩湧�牴��搭��瑩�睡�獨慰�昀

1ayersmoreandmore.Thesandstoneinthe1ateOgawaStageistu伍aceousandispart1yinterca1ated

withtheBδdairaTu旺Member.亙urthermore,inthe1owerpartoftheSusobanaFomation,acidic

vo1canicactivity,forexamp1e,rhyo1itictu旺and1avadominate.

周��捥�敲潦�楳癯�慮楣慣瑩癩�楳��楫楡�慮��瑩捶漱��捴�楴��

o㏄ursthere1ater.Themaincenterofthiseruption1ocatesnearNaganoCity.Asthewe1dedtu任is

おmdintheSusob乱naFormationaroundMt.Kamuriki,apartoftheseeruptionseemstohave

occuredonthe1andsur血｡e.

ThethicたnessoftheOgawaFormationisverythininthisarea.

These血｡tssuggestthatthereisthe1oca1mconおrmityintheSusobanaFormationaroundMt.

Kamuriたi,andthatthisareabegantoup1i冊1oca11y缶｡mthe1ateOgawaStage.Weakわ1dswhich

㎞1dstrendnear1yE-Wdeve1opearo㎜dMt.Kamurikianda1ongOmiRiver..Intheaxia1partofthe

Kom軸Sync1ine,thesinkingofthebasininwhichtheKomOiFormationdepositedsti11continued.

BeおretheeruptionofHOiriyamaVo1canicRocksanda冊erthesedimentationoftheKom箏iFormation,

�慴楳��牡�潭��潮睡�潭楮慮瑤楲散琱�琱��楮��敢��

Asthe1ayershad.initia1de且ectionsasdescribedintheprevioussections,initia1dips(maybe1ess

than10degrees)wereemphasized-bythiscompressionand-theytookthepresentwaWおrm.This

processasdescribe〔1aboveisrough1yin亙igure45.

6.C⑪苅｡亘咽s量｡飢s

Thepurposesofthisstudyhavebeentode丘nethe比1dingsty1esinthenorthem亙｡ssaMagna

Region,toana1yzethedeおrmationmechanismわrthoseわ1ding,tomakeclearthetectonicstress

丘e1dofthisregion,andtodiscusstheわ1dinghistory.Theお11owingconc1usionsaredrawn舟｡mthe

丘e1dsurveyoftheHigashi-ChikumaDistrict,NaganoPre此｡ture,andtheam1ytica1studiesofお1ding

一一126一�

㌫㌃ll㌃∴～畑㎏帆叫阻阿

サ

πム幽棚鴫､幽､蛾

劣㌣ζ

駅幽蝸蝸鍋

二篶炉伽一価桃㎏軌陶

㈹)畑舳㎎拙帖～拙伽､血㎞拙

一127_�


orogenesis.1;α〃.0301,806.■4〃一.,vo1.72,p.1595_1632.

C0BB0LD,P.R.(1975)Fo1dpropagationinsing1eembedded1ayers.皿6腕｡ψ仙5ω,vo1.72,p.333_351.

CURR肥｡J.B.,PATN0DE,H.W.andTRUMp,R.P｡(1962)Deve1op蛆entoffo1dsinsedimentarystrata.

一8ω〃.G301,806.■㎜.,vo1.73,p.655_674.

DIETERIc亘,J.H.andCARTER,N.L.(1969)Stress-historyoHo1ding.∠㎜.■o肌86{｡,vo1,267,p.129_154.

亙UJiM0T0ヨH.θまα1｡(1946)Geo1ogyofNaganoOi1Fie1d･万〃〃･Gθo1･806･■ψ伽,vo1･52,P･48-55･

亙UJITA,Y.(1973)τ加%γ㎜α肋〃げ｡∫ψα伽∫31151伽ゐ.一7加G閉柵4ψ〃｡砂θ脇〃ま.Tsuk巧iShokan,Japan.

肋鮎zAwA,M.(1972)Geo1ogyofSakaiVi11ageintheHigashi-Chi良umaDistrict,NaganoPrefecture

(M1S.).To吋｡UniversityofEducation.

貫AFNER,W.(1951)Stressdistributionandfau1ting.肋1.G301,806.肋.,vo1.62,p.373_398.

HARA,I.(1965)Move㎜e皿tpicturesincon丘nedco㎜petent1ayersinflexura1fo1ding,Defor蛆ationof

heterogeneous1y1ayere(1rocksin且exura1fo1d五ng(I).ノ｡鮒.0ω1,806.■ωψα脆,vo1.72,p.363-369.

��却牡楮慮�浯癥浥��潭��敲��數��景�楮本�景�慴楯湯晨整敲�

geneous1y1ayeredrocksin且exura1fo1ding(II).ノ｡〃.Gω1,806｡ノ｡ψα〃,vo1.72,p.413_425.

HET酬YI,M.(1946)Bea㎜one1asticdefomation.ω払〃肋{g"〃〃∬,AnnArbor,Mich.p.255.

肋趾BAYAsHI,T.(1969)AboutMatsu㎜oto-N確anoLineandOtariUp1冊ingBe1tinthenothem亙｡ssa.

Magn乱.0301,806.■ψ伽,“Somep1oble㎜saboutGreentu旺",p.117_122.

H0NMA,F.(1931)8勅α〃｡-6肋肋0肪脇∫〃∫肋.KokinPress.

HUDLEsT0N,P･J･(1973)Anana1ysisof“sing1e-1ayer,'fo1dsdeve1opedexperimenta11yinviscous㎜edia･

7-36な｡〃｡ψ砂5あ5,vo1.16,P.189-214.

彡�協��乳�丬��敲獨��湧慮�漱��癥��敢��潦

sing1e1ayers.7一κ'o〃｡ψ妙∫あ∫,vo1･17,P･299-321･

I叩MA,N.andSAIT0,Y.(1968)8〃ω〃旭ω伽4Hα桃加ηω0肋肋0腕∫棚5伽肋.

IKEDA,Y.andSHIMAM0T0,T.(1974)N皿merica1experimentsontheviscousbendingfo1ds.刀α〃｡0ω1,806.

ノ"ψ"〃,vo1.80,p.65_74.

IT0,T.(1976)Aboutthe㎜echanismoftbeNanakuraAntic1inenear亙ut包tsui,AkitaPrefecture.Abstract

潦�攸��卯��測��

IT0I,M.(1972)AbouttheTertiaryFor醐ationsinShiodaDistrictinUedaCityヨNagamPre£ecture(MS.).

�歹��癥�楴��瑩潮�

J0HNs0N,H.Ml.(1969)Deve1op㎜entoffo1dswithinCarme1Formation,ArchesNationa.IMonu㎜ent,

'Utah｡τを6òηoψ砂3北∫,vol.8,p.31_77.

andH0NEA,E.(1975)Atheoryofconcentric,kin長2mdsinusoi曲1fo1dingandof㎜onoclinica1

丑exuringofcompressib1ee1asticmu1ti1ayers.皿6腕｡ψ伽{63,vol.27,p.1_38.

KAsAHA趾,C.(1973)Thestratigraphyandthegeo1ogica1structuresinthewestemareaofHonj6Vi11age

inthe亘igashi-ChiヒumaDistrict,NaganoPrefecture(MS.).TokyoUniversityofEducation.

KAT0,H.(1970)The1包teMiocene£o1dsalongtheOmiandKanakumaRi∀ers,NaganoPre£ecture,一The

ana1ysisof£o1ds,Part.1.1地〃.0ω1,806.■勿ψα〃,vo1.76,p.579_590.

(1971)A㎜orpho1ogica1ana1usi竃｡ffo1ds,一Resu1tonthefo1dsa1ongtheRiverOmi,Nagano

Prefecture,Japan.β〃〃.0θo1.ぶ06.ノωψα拠,vo1.77,p,323-326.

一(1973)Son1econs1derat1onsabout£oIdIn.ode1s3班〃0301806｡∫"ψω勿,v0179,p157_166

(1975)Experimenta1studyoftheelasticbuck1ingfo1ds.3〃〃｡θ301,806･ノαψ仰旭,vo1.81,P.147-154.

KAwAUcHI,K.(1973)Geo1ogyofO㎜iandSak乱kitaVi11agesintheHigashi-ChikumaDistrict,Nagano

Prefecture(lM1S.)｡TokyoUniversityofEducation.

KIKUcHI,S.(1973)TheTertiaryFor皿ationsnearAokiVi11ageintheChiisagataDistrict,NaganoPre-

fectureinthenorthern亙｡ssaMagna(lMlS.).TokyoIUniversityofEducation.

KINUGAsA,Y.(1974)Photoe1asticexperimentsofthetransversebending.R砂ま.0301.8㈹｡■ψ伽,no.250_2,

��

K0BAYAsHI,K｡(1957)Thegeo1ogicdeve1opInentin正｡ssaM包gnaRegion.0腕9α后刎一0"〃α{K伽砂〃た切{･

��慮��潦��慳��慮��慳��物捴楮�条湯��

Fie1d,NaganoPrefecture.R吻.αo1.8脈θ｡ノψ伽,no.135,p.1_26.

K0DAMA,K｡〃α1.(1974)0ntheintema1structureofbox-shaped£o1ds.Rψ.αo1.｡∫〃rη.■ψω〃,no.250_2,

P,121-143･

K0MATsU,N.(1967)Aboutthegeo1ogica1structuresofTertiary亙｡rmαtionsinthemarginoflMatsu㎜oto

弱㈸�

正｡1dsofMiocene亙｡rmationsin貫igashi-Chiku㎜aDistrict,NaganoPre胎｡ture,Centra1Japan(H.

KへTO)

Basin･万〃肋86ユ舳63,voI.21,P.19-20.

KUTsUzAwA･A･㎜d亙UJITA･Y･(1967)Genesisofc1astic砒esandp1ane1ess脆u1tsintheMiocenedeposits

oftheSendaidistrict,一Studieson血u1tsatthebounda･ryofsedim,entarybasins(2).8〃〃.Gθo1,

806.･ノαψ"脆,vo1.73,P.19-34.

MERUI,S.(1972)TertiaryFor皿乱tionsintheeastempartofShigαVi11ageintheHigashi-ChikumaDistrict,

NaganoPre胎｡ture(MS.)｡TokyoUniversityofEducation.

Mo0DY,J.D.andHILL,M.J.(1956)Wrench血u1ttectonics.肋〃.G301,806.■㎜｡,vo1.67,p.1207_1246.

M0RIsHITA,A.助切1.(1957)Geo1ogyofthesouthempartofH軸ri-yama,･NaganoPre此｡ture,_0nthe

stratigraphyofso-ca11ed“T6chikuFacies"intheOgawaFor㎜ation.万〃〃.αo1,806.ノψω〃,vo1.

��弱��

NAGAHAMA,H.(1963)CrossbeddingsintheTertiary正｡rmationofJδbanCoa1万ie1d.肋〃.0θo1.1∫㈹.■αμ旭,

癯��弸��

NAGUM0,S.(1966)Thedyna㎜ictheoryof砧1ding.βω〃.θ301,806.山畑柵,vo1.72,p.117-130.

NA蛆MURA,K.(1969)Arrangementofparasiticconesasapossib1ekeytoregiona1stress丘e1d.肋〃.吻16.,

癯��

RAM跳RG,H.andSTEpHANss0N,0.(1964)Co㎜pressionofHoatinge1asticandviscousp1atesa冊ectedby

ぴavity,Abasis血rdiscussingcrusta1buck1ing.皿6肋｡ク砂3あ∫,vo1.1,p.101-120.

SAI肌wAREsEARc回GRoUp(1966)Geo1ogica1structuresoftheSai-kawaFracturedZone.一Geo1ogyofthe

S乱i-kawaArea,NaganoPre胎｡ture,CentralJapan(Part4).〃｡狗｡gr砂ゐ12,ム306.G301,001腕｡γ肋｡胞

■αψ"〃,P.94-102.

十��央��業楮��潴��捴��潦��敲瑩��瑩潮��湯牴��

partofthe亙｡ssaMagna･1書〃〃･1i〃･E♂刎6･8脆加5ゐωσ胞加.,no.12,P.99-108.

(1961b)Aninterestingso1emarkingobserve〔1onovertumedsandstone1ayersoftheAokiForm現一

tion(Neogene)in旺usaka一㎜ura,Higashi-Chikuma-gun,NaganoPre此｡ture,Japan.■o倣.肋6.

1班〃6.8肋肥曲〃0あ加.,no.12,p.I61_163.

SAKAI,M.(1976)Numerica1ana1ysisofviscousbend三ngro1dsbytheup1i航ingand/ordownward㎜ovem.ents

ofthebasement(MlS.).ShibauraIndustr三a1University.

SANF0RD,A.R.(1959)Ana1ytica1an(1experimenta1studyofsing1egeo1ogicstmctures.万α〃.Gθo1,806.〃刎.,

癯��

SHIMAM0T0,T.andHARA,I.(1976)Geometeryandstraindistributionofsing1e-1ayer比1ds.皿6肋ψ砂55ω,

癯�㌰��

SKJERNAc,L(1975)Experimentsonsuperimposedbuck1efo1ding･皿6肋ψ伽ξω｡vo1.27,P.255-270.

SUzUKI,Y･andMITsUNAsHI,T･(1974)Geotectonicdivision,geo1ogicdeve1op蛆entandmechanismsof

fo1dinginthenorthern亙｡ssaMagnaregion.R砂サ.0301.8鮒砂.∫αψ"胞,no.250-2,p.79-91.

TA肥uc亘I,A.andSA蛆M0T0,M.(1976)Stratigraphyandgeo1ogicstructureoftheNeogenesyste㎜inthe

midstreamdrain乱geoftheRiverSai士awa,N乱ganoPre胎｡ture,Centra1Jap乱n.〃舳.θθoム806.

ノωψ仰拠,no.13,P.187-201.

TAKEUcH亘,N･(1971)Geo1ogyinthewestcoastofChiku㎜aRiverinHanishina-gun,NaganoPre此｡ture

(MS.)｡TokyoUniversityofEducation.

TANA鮎,K.(1958)Geolo駆intheupperstreamofAidaRiverinthe㎜idd1epartofNaganoPre此｡ture.

1…〃1.ハω.1〃〃6.8腕〃J乃勿01㎜加.,p.267r276.

_andSEKI,H(1966)TheTert1aryFomat1ons1nthenorthofMats㎜ユ｡toC1ty肋〃肋醐刎6

8肋焔3尻勿σわあ.,no.18,p.139_159.

一切"1(1973)Stud1esonthesed1mentarystructuresobservedmtheTert1aryEor㎜at1onsmthe

northernpartof亙｡ssalM1agna.万α〃.ハ〃.1砒泌｡8胎5犯∫乃勿σ犯あ.,no.7,p,49_88.

��牡瑩杲慰�慮摧��捴��晴�卵��慷�敧楯��

northempartofNaganoPrefecture.肋〃.αo1,806.■ψ伽,vo1.59,p.552_560.

TsUN0DA,F･(1973)Studiesonfo1dsoftheMioceneMo㎜onokiSubgroupintheKo㎜乱Massif,Centra1

Ja.pan.ScienceReportTokyoKy6ikuDaigaku,SectionC.(Gθogr.αo1.舳♂〃加3〃｡gツ),vo1.11,

�㈶�㌱㌮

UEMU㎜,T.(1971)Aboutthegeo1o事｡alstructuresintheGreentu任region.α3励軌no.3,p.17_18.

_andTAKAHAsHI,A(1974)K1ne独at1cp1ctureofbasementrocksandお1dmgofover1y1ng1乱yer,_

Anexa㎜p1eofKushig乱taM1ountainRange,Niigat乱Pre胎｡ture,∫apan.Rψ.θ301.8鮒〃..1ψ〃〃,

一129一�


湯��

WILus,遇.(1894)MechanicsofAppalachinstr皿｡ture.ひ且G301.8㈹.13筋,〃胞.助｡〃,p.213-281.

YAMAGIsHI,I.功泓(1963)Thegeo1ogyofUeda-Chiisagat包District,vo1.4,p.5-252.

地名英和対応表

Age･6上篭A･u㎜･ya･乱n四阿屋山O㎜i麻積

K乱㎜urikiya㎜a冠着山K6sδ高桑Saig榊a犀川

Shige重Sh巾hachi則乱garit6ge四十八曲峠Shunaratδge修那羅峠

腕daira坊平Ho趾ψ保福寺Macchi末地

Yakyi矢久Yagoshi矢越

Oubaya㎜a大姥山

Sa･hi止i･i差切

Nishikibe錦部

Matsut･me松留

長野県東筑摩郡の中新世の摺曲について

加藤磧一

本論文の目的ほ,北部フォッサマグナ地域に分布する新第三紀中新世層中に発達する榴曲の様式を決

定し,その形成機構を明らかにして,当地域の構造発達吏を論じようとするものである.

長野県東筑摩郡を中心に約350km2におよぶ地域を野外調査し,その結果と室内での実験的研究から

次のことを明らかにした.

1.実験的研究から期待される座屈摺曲の形態特性,すなわち,振幅一波長比,平均短縮量や翼間色

などの分布特性が,自然摺曲とくに辺地向斜や野間背斜などのそれとよく一致する.

2.実験的に得られた座屈榴曲の歪分布と,自然摺曲中に発達する各種の小構造の解析から得られた

歪分布カミ少なくとも定性的に一致する.

3.主榴曲群は,基本的には座屈榴曲とみなされ,裾花層･小川層や木戸部属カミコンピｰテント層に

相当すると考えられる.

4.小摺曲(波長が数100m以下)も座屈摺曲であり,コンビｰテント層とみなされる砂岩0礫岩と

インコンピｰテント層とみなされる砂質泥岩とのコンビｰテンシィ国コントラストは,.きわめて小さ

く,このことは小摺由形成時に層平行短縮のあったことを暗示する.また,小摺曲の軸長と波長は,厳

密には必ずしも1対1の対応を示さないが有意な関係を持つ.

5｡主摺曲のみならず小摺曲も,層厚や層相の変化部や地層堆積時の隆起部など地層が形態的に不規

則な場所に発生し,そこを頂部とする傾向が強い.

6.松本一長野線は,摺由形成に関して重要な構造線であり,この線を境として東西で造構運動･火

成活動｡堆積作用に顕著な差異が見られる.とくに摺由形成期である中一後期中新世において東部地域

は引張応力場にあり,西部地域は圧縮領域にあること沽小断層,小摺曲や岩脈の解析から推定され

る.

7.座屈をおこした側圧は,基盤ブロックの傾動的隆起によるものと考えられる.

8.結局,当地域の摺曲は,基盤の差別的沈降運動によってできた初期波形を持つ被覆堆積岩層が,

犀川破砕帯以東の地域や中央隆起帯の傾動隆起に伴って発生した2次的水平圧縮力によって見かけ上大

きく座屈し,初期波形が強調されて現在みられる形をとるに至ったものである.

(受付:1978年3月20目;受理:1978年7月5目)

_130一�

蝋 ii 婁 Hirokazu KATO 藷 - gsj.jp

Documents