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Palynological Investigation of the Holocene Hojozu Submerged Forest in Toyama Prefecture, Central Japan

著者 Fuji Norio

journal or

publication title

金沢大学教育学部紀要 自然科学編 = Bulletin of the Faculty of Education, Kanazawa University.

Natural science

volume 22

page range 121‑135

year 1973‑12‑20

URL http://hdl.handle.net/2297/22353

(2)

121

PalynologicallnvestigationoftheHoloceneHojozuSubmerged

ForestinToyamaPrefecture,CentralJapan*

--PalynologicallnvestigationsontheQuaternarySysteminJapan(3)-

NorioFUJI**

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UEHTPAJIもHMmOHHH

nA川HOnO「HIIECKHEHCCJI皿OBAHHHIIETBEPTⅢH0画CHCTEMblHIIOHI'Ⅶ(3)

HopHoのymKH**

AHHOTAUHH

Pe3yJIBTaTbunaJIHHoJIorlluIecKHxHccJIe皿BaHHii3axopoHeHHoroJIecaXomKo3ycJIenyIoume:

(1)Bo3pacT中opMHpoBaHHH3axopoHeHHoroJIecaMo》KeT6bITbJIH60caMblMMo3皿HH

HoiicKHM,JIII60caMuMpaHHHMnepHo皿MⅡpeBHHxIpo6HHU,T、e、1600-1500JIeTToMy

Ha3aⅡ.

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(3)npHHHHad)opMHpoBaHHH3axopoHeHHoroJIeca6blJIa,no-B皿HMoMy,no皿HTHeypoBHH

MopH,IITo60JIeeBepoHTHo,ueMnorpy)KeHHe6eperoBoiiJIHHHHmoJIb6yxTuToiiHMa、STC

、皿HHTHeypoBHHMoPHH3BecTHoKaKHoiicKaJITPaHcrPeccHH.

(4)naJIeoKJIHMaT,BKoTopoMnpoH3pacTaJIHⅡepeBbHⅡoo6pa30BaHHHnorpy》KeHHoro (3axopoHeHHoro)JIeca6blJIxoJIo皿ee,uIeMBHacTomeeBpeMH・TeMneppaTypa6LIJIa

npH6JIII3HTeJIbHoHal-2・HmKecpe皿eiiTeMnepaTypaBcoBpeMeHHoeBpeMH、BpeMH

nOXOJIO瓜aHHHMO)KHOCPaBHHTbCoBPeMeHeMHe3HaTHTeJIbHorOOnyCKaHHHyPOBHHMOPH,HTO

cooTBeTcTByeTcepeⅡHHeTpeTEeroEMoHcKoroneplloⅡa-caMoMyno3ⅡHeMyHoiicKoMyBpe-

MeHH,JIH60caMoMypaHHeMynepHoJIy叩eBHHxrpo6HHu.

*:ReceivedSeptember7,’73;theContributionfromthelnstituteofEarthScience,Facultyof Education,KanazawaUniversity,NewSeriesNo、36;readJune25,,65,atthe90thMeeting ofthePalaeontologicalSocietyofJapanheldatKanazawaUniversity.

**:InstituteofEarthScience,FacultyofEducation,KanazawaUniversity.

(3)

第22号昭和48年 122金沢大学教育学部紀要

Introduction

TheHOjozudistrictissituatedintheinnermostpartofToyamaBay,beingchara- cterizedbythedeltaicdeposits,typicalfans,LagoonHojozu,somesubmergedforests

andsomedrownedvalleys・

TheHOjozuforestwasreportedfirstbythelateLIsHIエ(1936).Hestatedasagood

evidenceshowingthesubsidenceofground(IsHII,1.1938,1940-1941).Hereferredto WAKェMIzu'sopinionthatthesubmergedforest,whichwassubjectedtosuddensinking,

wasrepresentedonlybyimmersedtrunks・IsHIIconcludedthatthecoastofToyama

Bayhadbeensubmergedattherateofonly2・l6metersinl,OOOyearsandtheage

offormationoftheforestsaroundToyamaBaymightbeabout50,O00yearsago、

ThepresentwriterwasstudyingonthecoastalsanddunesandHDlocenealluvial depositswithpeatlayersandancientforestsoftheHokurikuregion、Thescopeof

thisarticleisthedeterminationoftheageofthisforest,palaeoclimate,geographical environmentsandoriginofthesubmergedforests・Thepresentreportisthethird

paperoftheseries,“PalynologicallnvestigationsontheQuaternarySysteminJapan,,.

GeologicalDegcrMnon

TheHojozudistrictisgeologicallycharacterizedbythedeltaicarea,typicalfans

andsomesubmergedforestsastheYokataforest・

Thedeltaicareanamedasthelmizuplainisawideplainandmighthavebeen

formedbysuchriversasShoRiver,JinzuRiverandJoganjiRiver・Thefanis

dividedintotwoareasastheJoganjiareaandShogawa‐OyabeareaThePleistocene terracesaredevelopedbetweenthesefans,jutingoutintothedeltaicarea・

LagoonHojozu,inwhichtheNewToyamaHarbourwasconstructedaboutenyears ago,issituatedatthecoastbetweentheShoandJinzurivers、Inthisdistrictthe

coastalsandduneextendsonlytonearLagoonHDjozu、

TheHolocenedepositsaremosttypicalinthelmizudeltaicarea,wheretherela-

tionshipbetweentheP1eistoceneandHolocenedepositsisknownbetterthanthosein

theotherareasofHokurikuregion,TheboundarybetweenthePleistoceneandHolo-

cenedepositsisfoundatadepthof45to50metersbelowthepresentsealevelat

thepresentcoast・

ThesedimentsduringtheHOlocenemajortransgressionnamedastheFlandrian

transgressionaremainlycomposedofmud,muddysandandsand、Judgingfromthe

somewelldrilledintheareaofthelowerpartoftheJinzuRiver,thegravellayer whichoverliestheHOlocenetransgressionaldepositsarefoundbetweenabout20meters and5metersbelowthepresentsealevelinthecoastalareas・Thelayershowsa remarkabledistributionatanaltitudeofaboutlOmetersabovethepresentsealevel ofthenorthernslopeofMt・Kureha-yamanearToyamaCity,andextendscontinually

(4)

FUJI:PalynologyofHoloceneHojozuSubmergedForestinToyama,Japan l23

I:50.000町形囚NJ-53S‐06

とや3(宮山I6gI 富山

蕊熱

鍋急Ajiii鑿i鍵

HEZli

iiiiliiiiiiiil灘!悪軒.雛 !I

鶴!;蕊ii

霧i震蕊■■も

i41蕊

弓Vg2mWW鋤弱EjaLjqr..?鄭鯛

【I

Fig.11ndexmapshowingthelocalityofthesamplesandthetopographyaroundtheHojozu

district,ToyamaPrefecture.

X:samplinglocality

thegravellayerofthelowerJinzuRiverabove-Inentioned・Thegravellayermight havebeenafanduringtheFlandriantransgressionalandregressionalages・

Thisdistrictisfamousforthedrownedvalleysandsubmergedforests、Thereare

thedrownedvalleysbeneaththepresentalluvialfansformedbytheJinzuandSho

revers,beingtracedtothesubmarinecanyonoffingthemouthsofabove-mentioned rivers・Thesubmergedforestsarefoundatadepthof5meterstolOmetersbelow

thepresentsealevelandaboutl50metersoffshoreofUchi,idega-hamabeach,Toyama

and2metersbelowthepresentsealevelataboutlOOmetersoffshoreofShin-minato・

Thosegeologicalandtopographicalphenomenasuggestthatalandwasprobablysunk

inthegeologicallyrecentage,perhapsduringthelast3,000years・

Thesubmergedforestshavebeenfoundfromsomelocalitiesalongthecoastof

(5)

124金沢大学教育学部紀要 第22号昭和48年

ToyamaBaysinceadiscoveryoftheUozu submergedforest・TheHDjozusubmergedforest calledinthisarticleincludestheUchi,idega- hamaandYokataforests・Theidentifiederect

1`wAil…"dstumpsareRzgz`Scγ812czfaBLuME.,〃g此zlzs

ajJα"オノレ加"α,Q"eγC2`SOJ`ZZ`CZZTnuNB.,Q,

s8〃αjaTnuNB.,CeγcizZiP〃yJJ"”ノZZPo"畑"z SェEB・etZucc.,MUzひ】DiJ2JsTノカ""68γ9がSIEB・et

pPQI

mny Zucc.,H、ノ9"iacZ"J“sTnuNB・andCa”eZJia

grOL,C/ SP・

ThegeologicalsuccessionoftheHDjozu districtisclassifiedintosixlayers,thatis,

、■●■

C●■●●●●ぜ●

■●。●●●0

11

p7PRe'MsPa-/P【'Pノ

i1灘113

Fig.2ColumnarsectionattheLocality

No、143oftheHojozudistrict, gravel(1meterinthickness),clay(0.5m),sand ToyamaPrefecture. (0.5m),clay(0.5m),darkbrownpeat(1m)

andsand(3m)layersinascendingorder、The gravellayerisconsideredtobelongtothefandepositswhichweresedimentedduring theHOloceneregressionalage、Theerectstumpsmighthavegrownontheclayand sandlayers、Thepeatlayerisnotfoundinthelowlandarea,beingoverlainbythe Newsanddune.

Radiocarbon14CDatingofErectStumpg

SomesamplesfromtheerectstumpsandthepeatlayersfoundintheHojozu submergedforestweredatedbyDr.KⅡGosmoftheGakushuinUniversity,Tokyoand theresultof14Cdatingisasfollows:

(1)CodeNo.GaK-539;apeaceoftheerectstumpfoundfromtheseabottomatabout lOOmetersoffshoreofYokata,ToyamaCity;samplingbyTamotsuTAKAsE;2,730±

90yearsbeforeA.D、1950.

(2)CodeNo.GaK-541;apeaceoftheerectstumpfromthemouthoftheJinzuRiver,

ToyamaCity;samplingbyShojiFuJエエ;1,950±110yearsbeforeAD、1950.

(3)CodeNqGaK-560;apeaceofdarkbrownpeatbelowarice-fieldsoilofHakko,

Shimo-mura;samplingbythepresentauthor,NorioFuJIandTamotsuTAxAsE;

3,780±100yearsbeforeA.D、1950.

(4)CodeNo.Gak-562;apeaceofdarkbrownpeatfromthecoastofHama-biraki,

Shin-minato;samplingbythepresentauthor;1,400±90yearsbeforeA.D、1950.

Theresultof14Cdatingabove-mentionediscomparabletotheresultof14Cdating ofsomeerectstumpsfromsomesubmergedforestsasUozuandAsahiforestssituated

alongthecoastofToyamaBay.

(6)

FUJI8PalynologyofHoloceneHojozuSubmergedForestinToyama,Japan 125

PM(s Plcea AbjPs CγyPto7Jle7jq Taxodiaceae CfLnγに CycQs PSemdots14gu A/mJs Ericaceae Hwle〃op/tz/〃'4"l

HZ/menopノiリノルmaff.γPC,イrtノ""I H"me〃op/tZノノルmaffspjcatn ScAjmea

Lgcopodjumsp・mdet、

Lycopodju",affc/uUdlw"I Lycopodj江maff.。γw",",o,Idj/

Lycopodj1イmdie7ustL",

L"godjwl Adjq7,tu"1 A[{.Adj(mtopsjS

AdjQ7ltopSjsQ〃:c/lmroPノ'"〃l7 Bot7"CAjum

DjcAso7Lju Aff・SpAagmjm Egmsemm

Sporeincerlaesedis

20% 10

PollenDiagram(Hojozu,LocalityNo,139)

F19.3PollendiagramfromLocalityNo、135oftheHojozudistrict,ToyamaPrefecture.

PalynologicalDescription

Forthepresentstudyl4samplesfroml41ocalitiesoftheHojozudistrictwere treated・TheresultofpollenanalysisisshowninFi9.3.Therelationshipamong thepollengrainsandsporesisreadfromthepollendiagram.

Am〕ngtho3easseznblage,Lyo”ocZj"”andAcZfα"ねPS′so“"pies36percentand7 percentrespectively・PjMz,Taxodiaceae(perhapsCγ”jo”eγ'αノヒIPO"iczzD・DON.),

S℃ノbjzagaandBoノアycハ2弛れeachshow5percent、PteridophytaasshowninFig、3occupies about70percentinthetotalfrequency,treesasPj"z`s,PZ“α,A6jesandCγjlPノoweγza arerare・Therefore,thepalaeotopographicalconditionofthattimemighthavebeen similartothepresentcondition.

Conclugion

TheresultofthepalynologicalresearchontheHojozusubmergedforestissum-

marizedasfollows:

(1)TheageofformationofthesubmergedforestseemstobethelastestYayoianor earliestO1dtumbperiod,about1,600or1,500yearsbeforethepresent.

(2)TheageinwhenmanytreesformingtheHojozusubmergedforestweregrowing upinthisareaseemstobeabout4,OOOtoaboutl,500yearsagofromthepaly- nological,stratigraphicalandradiochronologicalinvestigations.

(7)

126金沢大学教育学部紀要 第22号昭和48年

(3)Thecauseofformationofthesubmergedforestisduetotherisingofsealevel ratherthanthesinkingofthecoastalongToyamaBay・Therisingofsealevelis namedasYayoiantransgression.

(4)Thepalaeoclimateunderwhichthetreesweregrowingupbeforetheformationof thesubmergedforestwascoolerthanthatofthepresenttime・Itisaboutlto 2.Clowerthanthatofthepresenttimeinaveragemeantemperature・The decreasingwarmagemaybecomparabletothetimeoftheminorfallingofsea level,middleageofthethirdJomonianperiodtothelatestageoftheYayoian ortheearliestageoftheOldtulnbperiod.

ReferenceBCited

FUJI,Norio(1965):PalynologicalStudyontheA11uvialPeatDepositsfromtheHokurikuRegion ofCentralJapan;B"ノノ.Fac・Edb8D.Kα"αzazuaU)zj"eγsibノ,Nos、13andl4,NaturalScience andFuJII,Shoji(1967):PostglacialSeaLevelintheJapaneselslands;ノo”、Geosci.

OsabaCjfyu"/".,10,1,6.

-(1971):PalynologicallnvestigationoftheUozuSubmergedForestinToyamaPrefecture;

B"〃・FUzc.E`”.Kα"αzα〃αUクzizノ.,20,NaturalScience.

-(1972):PalynologicallnvestigationoftheHoloceneAsahiSubmergedForestinToyama Prefecture;B"〃.F加.E`z`c、Kα"αzα〃αU)zjz).,21,NaturalScience.

-andHoRIE,Shoji(1972):PalynologicalStudyon200metersCoreSampleofLakeBiwa inJapan;Pγocea伽sJcZPα〃Acade川,48,7.

1sHIX,Ittaro(1940-41):OntheRecentMovementoftheStrandLineoftheHokurikuDistrict;

J幼沈cP幼J、COか”c”oγαがo〃〃q7.YABE,S伽jcノノクBiγ/〃〃,11.

ExplanationofP1ateI

Figs、1&2:LycqPo`/"郷aff.cノaDaf…,Figs・frontofgrain,LOC・No.146,EKZJcolLcat・

no、20448,20449.

Fig.3:L)ノcOPo〃…,LOC・No.139,EKZJ20450・

Fig.4:ZJノc”o〃…aff・伽勿"E"80"〃,LOC、No.146,EKZJ20451・

Figs、5&6:Azノノα戒"獺,Fig.5frontofgrain,LOC、No.144,EKZJ20452・

Fig.7:Hy”e"⑫ノby""",frontofgrain,LOC・No.146,EKZJ20453・

Fig.8:Hy”eね⑫』!y〃”aff.γcc”、…,LOC・No.138,EKZJ20454・

Fig.9:Lyc”o`〃”Cf.〔わ"s…,LOC・No.141,EKZJ20455・

Fig.10:Z。'cqPo`〃”Cf.[た"s"〃8,LOC,No.142,EKZJ20456・

Fig.11:LycOPodjz`"zaff.。c"s“,LOC・No.142,EKZJ20457、

Fig.12:Lyc⑰M畑”Cf.〔ね"s…,LOC・No.149,EKZJ20458・

Fig.138ZJ'c”o`〃”Cf・ぬ"s"”,LOC、No.138,EKZJ20459・

Fig.148LJノcOPo`j"”Cf、此"s"加,LCD・No.138,EKZJ20460、

Fig.15:LycOPo`畑加,LOC、No.144,EKZJ20461・

Fig.16:LycOPodi"擁,LOC、No.147,EKZJ20462・

Fig.17:LycOPodjzJ”,LOC、No.150,EKZJ20463・

Fig.18:LycOPo`j…,LOC、No.150,EKZJ20464.

(8)

FUJI:PalynologyofHoloceneHojozuSubmergedForestinToyamaJapanplateI127

lii

18

(9)

第22号昭和48年

金沢大学教育学部紀要 PlateII

128

鰯 鰯

L」

(10)

FUJI:PalynologyofHoloceneHojozuSubmergedForestinToyama,Japan l29

ExplanationofP1ateⅡ

Figs、1&5:Adiα””sjsaff.cノレル、PノMJa,Fig.1frontofgTain,LOC・No.147,EKZJcoll・

Cat・no、20465.

Fig.2:BofがcAj2"",LOC,No.139,EKZJ20466、

Fig.3:Cf・DiO〃so郷α,LOC・No.139,EKZJ20467・

Fig.4:Aff・Spha0"…,LOC・No.150,EKZJ20468・

Fig.6:Bof,qyc〃如加,LOC,No.143,EKZJ20469・

Figs、7&8:Polypodiaceaegen、indet.,Fig.8frontofgrain,LOC・No.146,EKZJ20470・

Fig.9:Ericaceae,LOC・No.138,EKZJ20471・

Fig.10:Cf,Ly9o`〃”,LOC、No.141,EKZJ20472、

Figs、lldel2:Zdノc⑫odi…aff.d)W"侭)"o耐i,LOC、No.143,EKZJ20473、

Figs、13&14:Acfjα"mPsjsaff.Cルノoγ⑫ノセyJJa,Fig.13frontofgrain,LOC・No.144,EKZJ20474,

Figs、15.216:Ly9o`“”LOC,No.143,EKZJ20475、

Fig.17:Lyc⑫O脚”aff.〃z"""zoMi,LOC・No.146,EKZJ20476・

Fig.18:Bofがchj"”,LOC・No.137,EKZJ20477・

Fig.19:Aff.Sカルα0,604"Z冗伽γja””(bryophyta),LOC・No.139,EKZJ20478、

Fig.208Aff.Aノブα"f⑰sjs,LOC、No.146,EKZJ20479.

(11)

第22号昭和48年 130金沢大学教育学部紀要

ExplanationofP1ateⅢ

LOC・No.139,EKZJcolL Loc・No.143,EKZJ20482;

EKZJ20484;Fig.14:LOC・

LOC・No.141,EKZJ20487;

Figs、1,9,10,11,13,14,15,16andl7:incertaesedis;Fig.1:LOC・

Cat・no、20480;Fig.9:LOC・No.150,EKZJ20481;Fig.10:LOC・

Fig.11:LOC・No.143,EKZJ20483;Fig.138LOC・No.146,EK2 No、150,EKZJ20485;Fig.15:LOC、No.137,20486;Fig.16:LOC・

Fig.17:LOC・No.141,EKZJ20488・

Fig.2:Aff、Hy…“!”isSP伽fe;LOC、No.143,EKZJ20512・

Fig.3:Sporeincertaesedis;LOC・No.144,EKZJ20489、

Figs、4&5:Sb〃jzczeα;LOC・No.147,EKZJ20490,20491.

Fig.6:Spore(?)incertaesedis;LOC・No.146,EKZJ20492・

Figs、7&8:Sb〃jzaeczaff.。j,/〃α;LOC・No.147,EKZJ20493,20513.

Fig.12:Z〃cOPodj…;LOC・No.150,EKZJ20494.

(12)

FUJI:PalynologyofHoloceneHojozuSubmergedForestinToyama,Japan Platelll 131

於争。

lilllilll

|lIilI

OII

(13)

第22号昭和48年PlateIV 132金沢大学教育学部紀要

,,,''''''1iiliiillllilililiii

’①

(14)

FUJI8PalynologyofHoloceneHojozuSubmergedForestinToyama,Japan 133

ExplanationofP1ateⅣ

Figs、1&2:Spore(?)incertaesedis;LOC・No.143,EKZJcoll、Cat・No.20495,20511.

Figs、3&48Spore(?)incertaesedis;Fig.4:frontofgrain;LOC、No.150,EKZJ20496,

20497.

Fig.5:Eq郷sefz"";LOC・No.139,EKZJ20498・

Fig.6:LycOPo`j"”;LOC・No.140,EKZJ20499、

Figs、7de8:ZdPod吻加;LOC・No.149,EKZJ20500・

Figs、9&11:Cf、PSC"d、“α;Fig.9:LOC・No.142,EKZJ20501,Fig.118LOC・No.150,

EKZJ20502、

Fig.10:Cf.L”雌;LOC・No.150,EKZJ20503、

Fig.12:Aff.L)Uodi"”;LOC・No.148,EKZJ20504、

Fig.138QyCdzs;LOC・No.143,EKZJ20505・

Fig.14:Ly9o〃"郷;LOC・No.137,EKZJ20506・

Fig.15:LycOPodi…;LOC,No.139,EKZJ20507,

Fig.16:AJ“s;LOC、No.143,EKZJ20508・

Fig.17:Pollenincertaesedis;LOC、No.150,EKZJ20509・

Fig.18:Ericaceae;LOC・No.146,EKZJ20510.

(15)

第22号昭和48年 134金沢大学教育学部紀要

Exp1anationofP1ateV

Fig.1:PjMz,1ateralview,LOC・No.139,EKZJcoll・Cat・No.20436.

Fig.2:PjMz,1ateralview,LOC・No.138,EKZJ20437・

Fig.3:PjMz,1ateralview,LOC・No.150,EKZJ20438・

Fig.4:A6ics,1ateralview,LOC・No.150,EKZJ20439・

Fig.5:Pj""s'1ateralview,LOC・No.149,EKZJ20440 Fig、6:A伽s’1ateralview,LOC・No.137,EKZJ20441 Fig、7:Pj""8,obliquelateralview,LOC・No.139,EKZJ20442

Figs,8&9:Ci6yPfo沈螂αノ”o”cα’1ateralview,LOC・No.137,EKZJ20443,20444.

Figs,10,11del2:Taxodiaceae(Cf・G2yPfo籾刎α),1ateralview,LOC・Nos、146,150,139,

respectivelyEKZJ20445,20446,and20447.

(16)

FUJI:PalynologyofHoloceneHojozuSubmergedForestinToyamaJapanPlateV135

瀞iiIMlII

参照

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