Download presentation
1 -

Downloaded From httpsbiooneorgjournalsActaPalaeontologicaPolonic


KENICHIKURIHARASEIICHITOSHIMITSUandHIROMICHIHIRANOKuriharaKToshimitsuSandHiranoH2012AmmonoidbiodiversitychangesacrosstheCenomanianTuronianAmmonoidbiodiversitychangesfromshallowtooffshoreenvironmentsac

luna's Recent Documents

Tackling the Epidemic of
Tackling the Epidemic of

Low-Value Spendingand Medical OveruseOpportunities for Purchasersand CarriersDraftDocumentContents1 INTRODUCTION21-A TYPES OF WASTE3CLINICAL WASTE LOW-VALUE CARE/OVERUSE3CLINICAL WASTE OPERATIONAL WAS

published 0K
1960 Nature Publishing Group
1960 Nature Publishing Group

Nco 4731 July 2 1960 NATURE 7 Freshwater Biological Associations key 121 in Ward and Whipples and 60 are common but this is a group well known for its cosmopolitan distribution and in many others the

published 0K
Cite this article
Cite this article

ISSN 2471-6839Whitney Martinko review of Building the British Atlantic World Spaces Places and Material Culture 16001850 edited by Daniel Maudlin and Bernard L Herman Panorama Journal of the Associati

published 0K
UNOFFICIAL VERSION PENDING SUPREME COURT APPROVALGPCSF 18    11 Eff Ja
UNOFFICIAL VERSION PENDING SUPREME COURT APPROVALGPCSF 18 11 Eff Ja

ORDER DENYING PETITIONThe etition of for declarationof death of the abovenamed missing individual believed to be dead having come before the Court for hearing on and it appearing that notice of such h

published 0K
Frequently Asked Question
Frequently Asked Question

1P-EBTsQ What is P-EBTAPandemic Electronic Benefits Transfer P-EBT is asupplemental benefit for households with children who have temporarily lost access to free orreduced-price school meals due to pa

published 0K
Price Pump Co
Price Pump Co

INSTALLATION OPERATING AIR OPERATED ALL ELASTOMERS Price Pump Company POBox Q Sonoma CA 95476 Tel 707-938-8441 Fax 707-938-0764 Email salespricepumpcom PLEASE FILL IN DATA FROM YOUR PUMP NAMEPLATE Pum

published 0K
and areas Gramcalorie8 per horizontal surface
and areas Gramcalorie8 per horizontal surface

8QDXWKHQWLFDWHGRZQORDGHG3087WEATHER REVIEW 12 12 12 45 daily area - - -145 31 were decidedly most levels and southern from Table unusually large Royal Center Notwithstanding the subnorma1 free-air ave

published 0K
This PDFhas been retired Please visit
This PDFhas been retired Please visit

https//wwwcdcgov/antibioticuse/coreelements/pdfs/FactsheetCoreElementsCreatingCultureImproveUse508pdffor updated information

published 0K
Download Section

Download - The PPT/PDF document "" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.






Document on Subject : "Downloaded From httpsbiooneorgjournalsActaPalaeontologicaPolonic"— Transcript:

1 Downloaded From: https://bioone.org/jour
Downloaded From: https://bioone.org/journals/Acta-Palaeontologica-Polonica on 24 Aug 2021Terms of Use: https://bioone.org/terms-of-use KENICHIKURIHARA,SEIICHITOSHIMITSU,andHIROMICHIHIRANOKurihara,K.,Toshimitsu,S.,andHirano,H.2012.AmmonoidbiodiversitychangesacrosstheCenomanian…TuronianAmmonoidbiodiversitychangesfromshallowtooffshoreenvironmentsacrosstheCenomanian…Turonian(C…T)bound 57 (4): 749…757, 2012 C…TboundarybetweentheHakkinŠzawaRiversectioninHokkaido,Japan,andthePueblosectionintheWesternInteŠrior,USA.TheysuggestedthatthetimingoftheextinctionandrecoveryphasesformolluscanfaunaswasapproxiŠmatelysynchronousinbothsections.ThesescholarsconŠcludedthatthemolluscanfaunasinJapanwerestronglyinŠfluencedbytheOAE2.Theirapproaches,however,werereŠstrictedtoeventsinoffshorefaciesand/ordidnotexamineotherfactorsinsufficientdetail.Hence,itisnecessarytocomparefaunalchangesindifferentdepositionalenvironŠmentswithintheYezobasintounderstandtrulytheC…TmassextinctioneventinthenorthwesternPacificregion.Inthepresentpaper,ammonoidbiodiversitychangesfromshalŠlowtooffshoreenvironmentsacrosstheC…Tboundaryin.„CIU,carbonisotopicunit;CTBE,Cenomanian…Turonianboundaryevent;FAD,firstappearancedata;TheCretaceousYezoGroup,interpretedasforearcbasinsediments(Okada1983),iswidelydistributedincentralHokkaido,northernJapanandSakhalinIslandinFarEastRussia(e.g.,Takashimaetal.2004;Yazykova2004).Thisgroupwasprobablydepositedatapproximately35…45alongawestwardsubductionmargininthenortheasternAsiancontinent(Kodamaetal.2002).Thestratayieldabundant,wellŠpreservedmacroŠandmicrofossilsandtheyshowconspicuouswestŠtoŠeastfacieschanges(e.g.,Takashimaetal.2004).Forthepresentpaper,thefollowingthreeareaswereinvestigated(Fig.1):theMikasaarea(shelf…coastalplainsetting),theObiraarea(incisedvalley…outershelfsetMikasaarea.„ThesuccessionacrosstheCenomanian…Turonian(C…T)boundaryiscomposedmainlyofshallowmarinesandyfacies(MikasaFormation),ofwhichthedepositionalenvironmentsareinferredtohaverangedfromshorefacetooutershelf(Fig.2).TheCenomanian…Turonianboundaryevent(CTBE)isinthemiddleportionoftheMikasaFormation(Kurihara2006).WeaklylaminatedmudstoneisonlyobservedjustbelowtheC…Tboundary.Obiraarea.„ThesuccessionacrosstheC…Tboundaryiscomposedofsandymudstone,mudstone,andalternatingbedsofsandstoneandmudstone(Fig.2).TheCTBEisinthelowerportionoftheSakuFormation(HasegawaandSaito1993;Uramotoetal.2007,2009).LaminatedmudstoneisdominantwithintheCTBE.GreenishbioturbatedmudstoneŠlikeburrowsisdominantabovetheCTBE.ThedepositionalenvironmentisinferredtohavebeenoutershelfbecauseofthepredominanceofoffshoremudstoneOyubariarea.„ThesuccessionthroughtheCenomanian…Turonianiscontinuouslyexposed.Thus,manypalaeontoŠlogicalstudiesconcerningfaunalturnoverinvarioustaxahavebeenproposed(KaihoandHasegawa1994;Hirano1995;Hasegawa1999;KuriharaandKawabe2003;TakaŠhashi2005).ThelithofaciesacrosstheC…Tboundaryiscomposedmainlyofalternatingbedsofturbiditicsandstoneandmu

2 dstone(SakuFormation).TheCTBEisinthelowe
dstone(SakuFormation).TheCTBEisinthelowerportionoftheSakuFormation(HasegawaandSaito1993;Hasegawa1997).WeaklylaminatedmudstoneandgreenishbioturbatedmudstonewithŠlikeburrowsaredomŠinantwithinandjustabovetheCTBE,respectively.ThedepositionalenvironmentisinferredtohavebeencontinenŠtalslopebasedonfaciesanalysisandthemorphologyofcalŠcareousbenthicforaminifera(Kaihoetal.1993;TakashimaAmmonoidfaunasacrosstheCenomanian…TuronianboundarywereexaminedintheMikasa,Obira,andOyubariareas.ThereisanabundanceofmegafossildataintheCenomanian…Turoniantransitionofallareas(e.g.,Hiranoetal.1977;Tanabeetal.1977;Futakami1986;KuriharaandKawabe2003;FunakiandHirano2004;Takahashi2005;Kuriharaetal.2007).Inthepresentstudy,thestratigraphicalrangesfromthesepublishedandoriginaldataareusedfortheexaminationofammonoidbiodiversitychangesineacharea.TocomparetheammonoidbiodiversitychangesamongintraŠandinterregionalbasins(e.g.,Europe,theWesternInterior,andTunisia),weusecarbonisotope(C)stratigraphy(Fig.2)becausetheavailableintraŠandinterregionalACTAPALAEONTOLOGICAPOLONICA57(4),2012 Fig.1.Mapofthestudyareas(Mikasa,Obira,andOyubariareasinHok correlationofCretaceousCstratigraphybetweenterrestrialorganicmaterialsandmarinecarbonatesiswidelyaccepted(e.g.,HasegawaandSaito1993;Hasegawa1997;Uramotoetal.2007,2009;Takashimaetal.2010).Thestratigraphyhasalreadybeendocumentedinthesuccessionsstudied.Theammonoidbiodiversity,then,iscountedasthenumberofspecies(speciesrichness)occurringwithinacarbonisotopicunit(CIU)basedoncorrelationsfrompreviousstudies(Fig.2).Theextinction(E)andorigination(O)ratesKURIHARAETAL.„AMMONOIDSANDCENOMANIAN…TURONIANBOUNDARYINHOKKAIDO751 Fig.2.CompositecolumnarsectionsintheMikasa(),Obira(),andOyubari()areasandthestratigraphicallevelsofmacrofossildatumplanesusedinthepresentstudy.TheshadedportionshowstheCenomanian…Turonianboundaryevent(CTBE).ThemolluscanfossildataarefromTanabeetal.(1977),Futakami(1986),KuriharaandKawabe(2003),FunakiandHirano(2004),Kuriharaetal.(2007)andunpublishedoriginaldata.TheplanktonicforaminzonationandtheCTBEarefromHasegawa(1997,1999),Nishietal.(2003),Kurihara(2006),andUramotoetal.(2007,2009).Abbreviations:Ka,KatsurzawaFormation;Hk,HikagenosawaFormation;mdst,mudstone;sdst,sandstone;A.nipponicusActinoceramusnipponicusHel.helveticaglobotruncanahelveticaI.hobetsensisInoceramushobetsensisnonsulcatusI.kamuyInoceramuskamuyW.arc.Whiteinellaarchaeocretacea Erate=(numberofpreexistingspeciesabsentaboveeachCIU)/(totalnumberofspeciesbeloweachCIU)×100(%)Orate=(numberofsuccessorspeciesnotpresentbeloweachCIU)/(totalnumberofspeciesaboveeachCIU)×100(%)Inthepresentstudy,sixcarbonisotopicunits(CIUs)acrosstheCenomanian…Turonian(C…T)boundarywereused(Fig.3):(i)CIU1,correlatedtotheCunningtonicerasinermelowerpartoftheAcanthocerasrhotomagensezonesinEurope(earlymiddleCenomanian);(ii)CIU2,correlatedtotheupperpartoftheA.rhotomagense…lowerpartofthezones(latemiddleCenomanian);(iii)CIU3,correlatedtotheupperp

3 artoftheA.jukesbrownei…lowerpartoftheMet
artoftheA.jukesbrownei…lowerpartoftheMetoicocerasgeslinianumzones(latestmiddleCenomanian…earlylateCenomanian);(iv)CIU4,correlatedtotheupperpartoftheM.geslinianum…upperpartofthecerasdevonensezones(neartheC…Tboundary);(v)CIU5,correlatedtotheupperpartoftheW.devonense…lowerpartoftheMammitesnodosoideszones(middleearlyTuronian);and(vi)CIU6,correlatedtotheupperpartoftheM.nodosoŠNoneoftheCIUsintheMikasaareawererecognisedexceptCIU4.However,asthetimingofthefirstappearancedata(FADs)ofCunningtonicerasspp.(ammoActinoceramusnipponicusInoceramuskamuy,andhobetsensisnonsulcatus(inoceramids)wasrecognisedwithinCIUs1,2,3,5,and6intheObiraandOyubariareas,respectively(Fig.3),theFADsofthesespecieswereusedasproxydatumplanesinthisstudy,andtheboundariesofeachCIUweredefinedasthemiddleportionofeachspeciesintheMikasaarea.TheammonoidbiodiversitypatternswithineachCIUintheMikasa,Obira,andOyubariareasareshowninFig.4.Mikasaarea.„Theammonoidspeciesrichnessshowedpersistenthighvalues(12…13species)inCIU1andCIU2,thengraduallydecreased(6…7species),finallyreachingaminimum(4species)atCIU5.InCIU6,thespeciesrichnessincreasedagain(9species).Theextinction(Erate)andorigination(Orate)ratesrecordedhighvaluesbetweentheCIU1andCIU2intervals(Erate,67%;Orate,69%)andtheCIU2andCIU3intervals(EACTAPALAEONTOLOGICAPOLONICA57(4),2012 Fig.3.CorrelationofUpperCretaceousCstratigraphyofterrestrialorganicmaterialsintheMikasa,Obira,andOyubariareas,JapanandreferencestratigraphyofcarbonatesinEurope(afterJarvisetal.2006).Sixcarbonisotopicunits(CIUs)wereidentifiedinthepresentstudy.Abbreviations:e.,early;m.,middle;PDB,PeeDeeBelemniteStandard;AcanthocerasjukesbrowneiActinoceramusnipponicusAcanthocerasrhotomagenseCalycocerasguerangeriCunningtonicerasinertmeCollignoniceraswoollgariInoceramushobetsensisInoceramuskamuyMantellicerasdixoniMetoicocerasgeslinianumMammitesnodosoides rate,85%;Orate,71%),respectively.AlthoughthehighestvaluesofEandOrateswererecordedbetweentheCIU4andCIU5intervals,thecauseofthehighvaluesisinterpretedtoObiraarea.„Thespeciesrichnessshowedmoderatevalues(7…9species)inCIU1andCIU2;itthenabruptlydecreased(2species),reachingaminimum(1species)atCIU4.Subsequently,thespeciesrichnessincreasedagainatCIU5(8species)andpersistedwithamoderatevalue(9species)inTheErateshowedahighvaluebetweentheCIU2andCIU3intervals(77%)andtheCIU3andCIU4intervals(50%),respectively.ThehighestvalueofEandOratesduringtheCIU4andCIU5intervalsisinterpretedtobeduetothelowspeciesrichness.ComparativelyhighvaluesofEandOrateswererecordedbetweentheCIU5andCIU6intervalsOyubariarea.„Speciesrichnessshowedpersistentmoderatevalues(6…7species)duringtheintervalofCIU1toCIU3andthendecreasedatCIU4(4species).Subsequently,speciesrichnessincreasedabruptlyatCIU5(13species)andTheEandOrateswererelativelylowcomparedtothoseintheMikasaandOyubariareas.AhighOrate(85%)was.„BeforecomparingtheammonoidfaunasamongtheMikasa,Obira,andOyubariareas,weshouldnotethetaphonomicattributesoftheammo

4 noidfossils.Ammonoidshellsmayhavebeenpro
noidfossils.AmmonoidshellsmayhavebeenpronetopostŠmortemdrift,justasmodernshellssometimesappearinareasoutsideoftheiroriginalhabitatareabecauseofoceancurrents(e.g.,Stenzel1964).Forinstance,Maedaetal.(2003)demonstratedthatLatePalaeozoicammonoidsweretransportedfromoneormoredistantoffshorebiotopesinTexas,USA.Kawabe(2003)examinedthetaphonomicattributesofammonoidsinlateAlbian…CenomanianstrataintheMikasaandOyubariareasandpointedoutthefollowing:(i)encrustationbyorganismsandcorrodedoutersurfaces,whichareindicativeofshellsthathavefloated,areabsentfromsmalltomoderateŠsized(1…30cmindiameter)ammonoids;and(ii)theattributesofshellbreakageindicatethattheshellsdidnotendurelongŠdistancetransportoutoftheiroriginalhabitat.ThepreservationalfeaturesoftheammonoidshellscollectedinthepresentstudywerealmostcoincidentwiththoseillustratedbyKawabe(2003).Consequently,weassumethatthemolluscanfossilsinthepresentstudydidnotundergolongŠdistancetransportexceptforbriefpostŠmortemmovement.KURIHARAETAL.„AMMONOIDSANDCENOMANIAN…TURONIANBOUNDARYINHOKKAIDO753 Fig.4.Temporalchangesinammonoidspeciesrichness,extinction,andoriginationratesintheMikasa,Obira,andOyubariareas.Abbreviations:CI AmmonoidbiodiversitychangesintheYezoGroupThetemporalchangesofammonoidspeciesrichnessacrosstheCenomanian…Turonian(C…T)boundaryindicatethefollowing(Fig.4):(i)persistentlyhighvaluesduringthemiddleCenomanian(thecarbonisotopicunit1(CIU1)andCIU2intervals);(ii)agradualdeclinefromnearthemiddle…lateCenomanianboundary(theCIU3andCIU4intervals),especiallyininshoreareas(MikasaandObiraareas);and(iii)abruptrecoveryjustabovetheCenomanian…Turonianboundaryevent(CTBE)(theCIU5interval),especiallyinoffMonnet(2009)demonstratedthetemporalchangesofammonoidspeciesrichnessduringthelateAlbiantoearlyTuronianinEurope,Tunisia,andtheWesternInterior,wherearealltyperegions(oldstratotypesandrecentboundarystratotypes)fortheCenomanianandTuronianstages.Althoughhisdataareofamuchhigherresolutionthantheonesinthepresentstudy,thusmakingitdifficulttocomparedirectlythebiodiversitychanges,thereseemtobesomesimilaritiesandcontrastsbetweentheYezoGroupandotherreŠgions.ThetemporalchangesinspeciesrichnessintheYezoGroup,whichshowpersistentlyhighvaluesduringthemidŠdleCenomanianandasubsequentdeclinestepwisefromnearthemiddle…lateCenomanianboundary,resemblethoseinEurope(Monnetetal.2003;MonnetandBucher2007;Monnet2009)(Fig.4).ThisresemblanceindicatesthattheammonoidfaunasinJapanarecharacterisedbyasustaineddiversitydropdownsimilartothoseinEurope,showingthatthemassextinctionattheC…Tboundary,therefore,didtakeplace.Incontrast,speciesrichnessinTunisiaandtheWestŠernInteriorincreasesorremainsrelativelyhighacrosstheC…TboundarydespitethesynchronousdepositionoforŠganicŠrichsedimentscorrelatedtotheOAE2;therefore,noammonoidcrisisoccurred(Monnet2009).Hence,thesedifŠferencessuggestthattheCenomanian…TuronianmassexŠtinctionŽisnotaglobaleventforammonoidsasMonnet(2009)pointedout,andmoreover,the

5 massextinctionŽwasrestrictedtomidŠpalaeo
massextinctionŽwasrestrictedtomidŠpalaeolatitudinalregions(EuropeandJaPossiblecauseofammonoidmassextinctionintheYezo.„IntheMikasaarea,highvaluesofextinction(Erate)andorigination(Orate)rateswerenotedforthemiddleCenomanian(CIU1…CIU2boundary),eventhoughhighvaluesofspeciesrichnesspersisted(Fig.4).ThisobservationimpliesthatamajorfaunalturnovertookplacewithinashorttimespanininshoreareasoftheYezoGroup.Atthattime,ammonoidfaunaswerereplacedatthegenuslevel;forinstance,theacanthoceratidsinCIU1werereplacedbyinCIU2,andthekossmaticeratidinCIU1byinCIU2(Kuriharaetal.2007).Subsequently,acanthoceratidsandkossmaticeratids,whichsofarcomprisedthemaincomponentsofammonoidspeciesrichness,disappearedwithintheCIU2interval(Fig.5).Asaresult,desmoceratidspeciesdominatedduringtheCIU3toCIU4interval.ThelithofaciesintheMikasaarearepresentsinterŠbeddedfineŠgrainedsandstonewithhummockycrossŠstratiŠficationinCIU1andbioturbatedmuddysandstoneinCIU2(Fig.2).Moreover,offshoremudstonesaredominantinCIU3toCIU4.Thedisappearanceofacanthoceratidandkossmaticeratidammonoids,therefore,mayhavebeenafŠfectedbyshallowtooffshorefacieschangeswithtransgresŠsion.IntheWesternInterior,Batt(1989)inferredammonoidhabitatsintheCenomanianandTuronianstagesbasedontherelationshipbetweenmorphotypesanddistributionpatterns.Withinhisinterpretation,CunningtoniŠ(Group1inBattsstudy)weredominantanddiverseinshallowerareas,(Group2)inhabitedshorefacetodistaloffshoreareas,anddesmoceratids(Group7)weremostabundantinproximaltomedialoffshoremudfacies.Ourdata,therefore,conformtohishypothesis.However,inHokkaido,thefrequencyofacanthoceratidammonoidsismuchlowerthanthatoflessornateammonoids(i.e.,desmoceratids,gaudryceratids)invariousdepositionalenvironmentsduringthelateAlbiantoCenomanian(Kawabe2003).ItisthereforenecessarytoinvestigatetherelationshipbetweenspeciesdiversityandfrequencyoftheammonoidspeSpeciesrichnessstilldecreasedneartheC…Tboundary(CIU4)inallareas.LaminatedorweaklylaminatedfaciesweredominantintheYezoGroup.InanopenoceansuchasthePacificregion,highsurfaceproductivity,whichispromotedbycoastalupwellingandaninflowofnutrients,developsthemidŠwateroxygenŠminimumzone(OMZ)(Arthuretal.1987;Erbacheretal.1996).InacontinentalmarginsuchastheYezobasin,therewerehighcoastalupwellingsandaninflowofnutrientsbyamajorwidespreadtransgressionneartheC…Tboundary(Arthuretal.1987;KruijsandBarron1990).TheconspicuousabundanceofdinoflagellatecystssupportsACTAPALAEONTOLOGICAPOLONICA57(4),2012 Fig.5.TemporalchangesinfaunalcomponentsofammonoidspeciesrichnessintheMikasaarea.Abbreviations:CIUs,carbonisotopicunits;e., highproductivityneartheC…TboundaryintheYezobasin(KanekoandHirano2005),andthepredominanceofoffshoremudstonetowardstheC…TboundaryintheMikasaareareflectssealevelrise(Fig.2).Thesephenomena,therefore,suggestthatthemidŠwaterOMZwasexpandedandintensifiedupanddownthewatercolumnneartheC…TboundaryintheYezobasin.CalcareousbenthicforaminiferalmorphologyintheOyubariarea

6 supportstheappearanceofalowoxygenenviron
supportstheappearanceofalowoxygenenvironmentneartheC…Tboundary(KaihoandHasegawa1994).However,asmentionedabove,ammonoidspeciesrichnesshadalreadydecreasedfromnearthemiddle…lateCenomanianboundary,priortotheexpansionoftheOMZ.ThisfactdoesnotdenytheinfluenceoftheOAE2ontheammonoidspeciesdiversity,ratheritmeansthatthedecreaseofdiversityofammonoidsintheYezoGroupwasnotsolelycausedbytheOAE2.Thereisaquestion,then,astoprimarycauseofthereductionofdiversityinammonoidsintheYezoGroup.GiventhevariousabioticchangesduringtheCenomanian…Turoniantransition(e.g.,Haqetal.1987;Jenkynsetal.1994;Erbacheretal.1996;Braloweretal.1997;ClarkandJenkyns1999),itisunlikelythatasingle,simplecauseledtotheC…TboundarymassextinctionŽ(Monnet2009).However,amajortransŠgressionmaybeakeyfactorinammonoiddiversityreductionintheYezoGroupbecausespeciesrichnessdeclinedstepwisefromnearthemiddle…lateCenomanianboundarywithchangesoffaunalcomponents,especiallyininshoreareas,andthetimingofthediversitydropiscoincidentwiththeonsetofthetransgressionintheYezoGroup.TheAlbiantoTuronianintervalischaracterisedbyaglobal2ndordertransgressivetrend,andtheunusualtransŠgressionpeakedintheearliestTuronian,whichrecordsthemostmarkedhighstandoftheMesozoic(HancockandKauffman1979;Haqetal.1987).SealevelchangecanseŠverelyalterthesurfaceareaofecologicallycriticalzonesoverthecontinentalshelvesandoceanographiccirculationpatterns(Smithetal.2001).TheunusualhighstandinducedashifttowarddeeperŠwaterenvironmentsduringthelateCenomanian,causingareducedpartitioningofepicontinentalseas(Monnet2009).Moreover,longŠtermOdatashowhighseasurfacetemperaturesduringtheCenomanianandTuronian(e.g.,Jenkynsetal.1994;ClarkandJenkyns1999;Wilsonetal.2002;Bornemannetal.2008).ThisglobalwarmingisalsocharacterisedbyareductionoftheequatorŠtoŠpoleseasurfacetemperaturegradient(BiceandNorris2002).ThereducedpartitioningofepicontinentalseasandthemoreequableclimatecontributedtothehomogenisationofmarinehabitatsduringthelateCenomanian,whichinturncausedadecreasingendemismanddecreasingspeciesrichness(Monnet2009).IntheYezoGroup,thereisadiscrepancyinlongŠtermCstratigraphybetweenterrestrialorganicmaterialsandmarinecarbonatesduringtheCenomaniantomiddleTuronian(Hasegawa2003;Takashimaetal.2010).Thecauseofthediscrepancyisunderstoodasadrivingforceforaclimaticoptimum.Hence,sealevelandclimatechangesprobablyinfluencedtheammonoidfaunasinJapanaswellasthoseinEurope.ThisconclusionispresumablysupportedbythefactthatthemassextinctionŽwasrestrictedtomidŠpalaeolatitudinalregionsbecausemarinefaunasatmidŠpalaeolatitudinalregionsmustbemoresensitivetoclimatechanges(i.e.,transitionalrealm).SeveralphasesoflargeŠscalevolcanicactivityareknowninthelateCenomanianorTuronian,includingtheCaribbean…Colombianoceanicplateau,theKerguelen(BrokenRidge)plateau,andtheOntongŠJavaplateau(e.g.,Kerr1998).TheeruptionoftheselargeigneousprovinceswasresponsibleforthedisruptionofthebiosphereattheC…Tboundarybothdirectly(duetovolat

7 ileandtracemetalŠenrichedhydrothermalflu
ileandtracemetalŠenrichedhydrothermalfluidrelease,sealeveltransgressionanddisruptedcirculationpatterns)andindirectly(duetoelevatedtemperaturesfromincreasedCO)(Kerr1998).IntheYezoGroup,frequentfelsictuffbeds,whichweregenerallyalteredtobentonites,areindeedobservableneartheC…Tboundary(especiallyintheearlyTuronian;Takashimaetal.2004),presumablyimplyingflourishingvolcanicactivity.However,nodetailedanalysisofvolcanicactivityhasbeendemonstratedintheYezoGroup,andthus,theinfluenceofvolcanicactivityonthechangesofammonoidbiodiversityisstillunknown.However,oneofthemostobviousphysicaleffectsofmantleplumeŠrelatedvolcanismintheoceanswillbetheriseinsealevel(Larson1991),andthesealevelriseprobablypredatestheonsetofsignificantvolcanism(Kerr1998).ThepossibilitythatlargeŠscalevolcanicactivityindiŠrectlyaffectedammonoidbiodiversityintheYezoGroup,AmmonoidbiodiversitychangesfromshallowtooffshoreenvironmentsacrosstheC…TboundaryarereconstructedintheYezoGroup,Hokkaido,Japan,whichwasprobablydepositedatapproximately35…45NalongawestwardsubductionmargininthenortheasternAsiancontinent.Thefol(i)TemporalchangesinspeciesrichnessintheYezoGroup,whichshowpersistentlyhighvaluesduringthemiddleCenomanian,thendeclinestepwisefromnearthemiddle…lateCenomanianboundary,resemblethoseinEurope,butnotthoseinTunisiaandtheWesternInterior.Hence,thesedifferencessuggestthattheCenomanian…TuronianmassextinctionŽisnotaglobaleventforammonoidsandthatthemassextinctionŽwasrestrictedtomidŠpalaeolatitudinalregions(EuropeandJapan).(ii)SpeciesrichnessstilldecreasedneartheC…TboundaryintheYezoGroup.Laminatedorweaklylaminatedfaciesweredominant,andoxygenŠdepletedconditionswidespread.However,ammonoidspeciesrichnesshadalreadydecreasedfromnearthemiddle…lateCenomanianboundary,priortotheexpansionoftheoxygenminimumzone.ThisfactdoesnotdenytheinfluenceoftheOAE2,butratherindiKURIHARAETAL.„AMMONOIDSANDCENOMANIAN…TURONIANBOUNDARYINHOKKAIDO755 catesthatthedecreaseinammonoiddiversityintheYezo(iii)IntheYezoGroup,sealevelandclimatechangesprobablyinfluencedammonoidfaunasaswellasthoseinEurope.However,itisunlikelythatasingle,simplecauseledtotheC…TboundarymassextinctionŽbecausevariousabioticchangesintheCenomanian…Turoniantransitionhavebeendetected,andthereareinterrelationsbetweenbioticandWeareverygratefultoClaudeMonnet(UniversityofZurich,Switzerland)andPaulWignall(UniversityofLeeds,UK)forhelpfulreviewsthatledtoimprovementofthemanuscript,toFumihisaKawabeandAkinoriTakahashi(bothfromWasedaUniversity,Tokyo,Japan),andRyojiWani(NationalScienceMuseum,Tokyo,Japan)forcriticalreadingofthemanuscriptandpertinentsuggestions,toHiroshiNishi,ReishiTakashima,andKazuyoshiMoriya((allfromKyushuUniver,Fukuoka,Japan)forconstructivepointersanddiscussionsandtoManabuKano(KochiUniversity,Japan)forassistanceduringourfieldArthur,M.A.,Schlanger,S.O.,andJenkyns,H.C.1987.TheCenomaŠnian…TuronianOceanicAnoxicEvent,II.PaleoceanographiccontrolsonorganicŠmatterproductionandpreser

8 vation.:J.BrooksandA.J.Fleet(eds.),Marin
vation.:J.BrooksandA.J.Fleet(eds.),MarinePetroleumSourceRocks,GeologicalSocietySpeŠBatt,R.1989.AmmoniteshellmorphotypedistributionsintheWesternInŠteriorGreenhornSeaandsomepaleoecologicalimplications.Batt,R.1993.AmmonitemorphotypesasindicatorsofoxygenationinaBice,K.L.andNorris,R.D.2002.PossibleatmosphericCOextremesoftheMiddleCretaceous(lateAlbian…Turonian).17:1070.Bralower,T.J.,Fullagar,P.D.,Paull,C.K.,Dwyer,G.S.,andLeckie,R.M.1997.MidŠCretaceousstrontiumŠisotopestratigraphyofdeepŠseasecBornemann,A.,Norris,R.D.,Friedrich,O.,Beckmann,B.,Schouten,S.,SinningheŠDamste,J.S.,Vogel,J.,Hofmann,P.,andWagner,T.2008.IsotopicevidenceforglaciationduringtheCretaceoussupergreenhouse.319:189…192.Clark,L.J.andJenkyns,H.C.1999.NewoxygenisotopeevidenceforlongŠtermCretaceousclimaticchangeintheSouthernHemisphere.Elder,W.P.1989.MolluscanextinctionpatternsacrosstheCenomanian…TuronianstageboundaryinthewesterninterioroftheUnitedStates.Erbacher,J.,Thurow,J.,andLittke,R.1996.Evolutionpatternsofradiolariaandorganicmattervariations:AnewapproachtoidentifyseaŠlevelchangesinmidŠCretaceouspelagicenvironments.24:499…502.Funaki,H.andHirano,H.2004.CretaceousstratigraphyinthenortheasternpartoftheObiraarea,Hokkaido,Japan[inJapanese,withEnglishabFutakami,M.1986.StratigraphyandpaleontologyoftheCretaceousintheIshikariprovince,centralHokkaido.PartI.StratigraphyandtheCretaceousinthesouthernareas.BulletinoftheNationalScienceMuseum,Gale,A.S.,Smith,A.B.,Monks,N.E.A.,Young,J.A.,Howard,A.,Wray,D.S.,andHuggett,J.M.2000.MarinebiodiversitythroughtheLateCenomanian…EarlyTuronian:palaeoceanographiccontrolsandsequencestratigraphicbiases.JournaloftheGeologicalSociety,LondonHancock,J.M.andKauffman,E.G.1979.ThegreattransgressionsoftheLateCretaceous.JournaloftheGeologicalSociety,LondonHaq,B.U.,Hardenbol,J.,andVail,P.R.1987.ChronologyoffluctuatingHarries,P.J.andLittle,C.T.S.1999.TheearlyToarcian(EarlyJurassic)andtheCenomanian…Turonian(LateCretaceous)massextinctions:similaritiesandcontrasts.Palaeogeography,Palaeoclimatology,PalaeoecolHasegawa,T.1997.Cenomanian…TuroniancarbonisotopeeventsrecordedinterrestrialorganicmatterfromnorthernJapan.Hasegawa,T.1999.PlanktonicforaminiferaandbiochronologyoftheCenomanian…Turonian(Cretaceous)sequenceintheOyubariarea,Hasegawa,T.2003.CretaceousterrestrialpaleoenvironmentsofnortheasternAsiasuggestedfromcarbonisotopestratigraphy:IncreasedatmoŠinducedclimate.JournalofAsianEarthSciencesHasegawa,T.andSaito,T.1993.GlobalsynchroneityofapositivecarbonisotopeexcursionattheCenomanian/Turonianboundary:ValidationbycalcareousmicrofossilbiostratigraphyoftheYezoGroup,Hokkaido,Hirano,H.1995.CorrelationoftheCenomanian/TuronianboundarybeŠtweenJapanandWesternInterioroftheUnitedStates.Journalofthe101:13…18.Hirano,H.,Matsumoto,T.,andTanabe,K.1977.MidŠCretaceousstratigraŠphyoftheOyubariarea,centralHokkaido.PalaeontologicalSocietyofJarvis,I.,Carson,G.A.,Cooper,M.K.F.,Hart,M.B.,Leary,P.N.,Tocher,B.A.,Horne,D.,a

9 ndRosenfeld,A.1988.Microfossilassemblage
ndRosenfeld,A.1988.MicrofossilassemblagesandtheCenomanian…Turonian(lateCretaceous)OceanicAnoxicEvent.Jarvis,I.,Gale,A.,Jenkyns,H.,andPearce,M.2006.SecularvariationinLateCretaceouscarbonisotopes:anewCcarbonatereferencecurvefortheCenomanian…Campanian(99.6…70.6Ma).GeologicalMagaJenkyns,H.C.,Gale,A.S.,andCorfield,R.M.1994.CarbonŠandoxygenŠisotopestratigraphyoftheEnglishChalkandItalianScagliaanditsKaiho,K.,Fujiwara,O.,andMotoyama,I.1993.MidŠCretaceousfaunalturnoverofintermediateŠwaterbenthicforaminiferainthenorthwesternKaiho,K.andHasegawa,T.1994.EndŠCenomanianbenthicforaminiferalextinctionsandoceanicdysoxiceventsinthenorthwesternPacificOcean.Palaeogeography,Palaeoclimatology,Palaeoecology111:29…43.Kaneko,M.andHirano,H.2005.DinoflagellatecystassemblagesandreconstructionofprimaryproductivityacrosstheCenomanian/TuronianboundaryintheObiraarea,northwesternHokkaido,Japan[inJapanese,Kauffman,E.G.1995.GlobalchangeleadingtobiodiversitycrisisinaGreenhouseworld:theCenomanian…Turonian(Cretaceous)massexEffectofPastGlobalChangeonLife.StudiesinGeophysicsKauffman,E.G.andHart,M.B.1995.CretaceousbioŠevents.:O.H.Walliser(ed.),GlobalEventsandEventStratigraphyinPhanerozoic:ResultsoftheInternationalInterdisciplinaryCoŠoperationintheIGCPKawabe,F.2003.RelationshipbetweenmidŠCretaceous(upperAlbian…Cenomanian)ammonoidfaciesandlithofaciesintheYezoforearcbaKeller,G.,Han,Q.,Adatte,T.,andBurns,S.J.2001.PalaeoenvironmentofACTAPALAEONTOLOGICAPOLONICA57(4),2012 theCenomanian…TuroniantransitionatEastbourne,England.Kerr,A.C.1998.Oceanicplateauformation:acauseofmassextinctionandblackshaledepositionaroundtheCenomanian…Turonianboundary?Kodama,K.,Maeda,H.,Shigeta,Y.,Kase,T.,andTakeuchi,T.2002.IntegratedbiostratigraphyandmagnetostratigraphyoftheUpperCretaceousSystemalongtheRiverNaibainsouthernSakhalin,Russia[inJapanese,withEnglishabstract].JournaloftheGeologicalSocietyofKruijs,E.andBarron,E.1990.ClimatemodelpredictionofpaleoproductivityandpotentialsourceŠrockdistribution.:A.ŠY.Huc(ed.),DepositionofOrganicFacies.AmericanAssociationofPetroleumGeologistsStudiesin30:195…216.Kurihara,K.2006.Cenomanian/TuronianBoundaryEventintheNorthŠwestPacific:MarineBiodiversityandPalaeoceanographicBackground36pp.UnpublishedPh.D.thesis,WasedaUniversity,Tokyo.Kurihara,K.andKawabe,F.2003.MolluscanfaunalchangesacrosstheCenomanian/Turonianboundary:AcomparisonbetweentheOyubariarea,Hokkaido,JapanandtheWesternInterior,USA[inJapanese,withKurihara,K.,Kawabe,F.,andHirano,H.2007.AmmonoidfaunasandstratigraphyoftheCretaceousYezoforearcbasin,Hokkaido,Japan.Larson,R.L.1991.Geologicalconsequencesofsuperplumes.Maeda,H.,Mapes,R.H.,andMapes,G.2003.TaphonomicfeaturesofaLowerPermianbeachedcephalopodassemblagesfromCentralTexas.Monnet,C.2009.TheCenomanian…Turonianboundarymassextinction(LateCretaceous):NewinsightsfromammonoidbiodiversitypatternsofEurope,TunisiaandtheWesternInterior(NorthAmerica).Monnet,C.andBucher,H.2007.Europeanammonoiddiversityq

10 uestionsthespreadingofanoxiaasprimarycau
uestionsthespreadingofanoxiaasprimarycausefortheCenomanian/Turonian(LateCretaceous)massextinction.SwissJournalofGeosciencesMonnet,C.,Bucher,H.,Escarguel,G.,andGuex,J.2003.Cenomanian(earlyLateCretaceous)ammonoidfaunasofWesternEurope.PartII:diversitypatternsandtheendŠCenomaniananoxicevent.Nishi,H.,Takashima,R.,Hatsugai,T.,Saito,T.,Moriya,K.,Ennyu,A.,andSakai,T.2003.PlanktonicforaminiferalzonationintheCretaceousYezoGroup,CentralHokkaido,Japan.JournalofAsianEarthSciencesOkada,H.,1983.CollisionorogenesisandsedimentationinHokkaido,Ja:M.HashimotoandS.Uyeda(eds.),AccretionTectonicsintheCircumŠPacificRegions,91…105,TerraScientificPublishingComSchlanger,S.O.andJenkyns,H.C.,1976.CretaceousoceanicanoxiceventsSepkoski,J.J.,Jr.1989.Periodicityinextinctionandtheproblemofcatastrophisminthehistoryoflife.JournaloftheGeologicalSociety,Sepkoski,J.J.,Jr.1996.PatternsofPhanerozoicextinction:Aperspectivefromglobaldatabases.:O.H.Walliser(ed.),GlobalEventsandEventSmith,A.B.,Gale,A.S.,andMonks,N.E.A.2001.SeaŠlevelchangeandrockŠrecordbiasintheCretaceous:aproblemforextinctionandbioStenzel,H.B.1964.LivingNautilus.:R.C.Moore(ed.),TreatiseonInvertebratePaleontology,PartK,Mollusca3,K59…K93.TheGeologicalSocietyofAmericaandtheUniversityofKansasPress,Lawrence.Takahashi,A.2005.ResponsesofinoceramidsbivalvestoenvironmentaldisturbancesacrosstheCenomanian/TuronianboundaryintheYezoTakashima,R.,Kawabe,F.,Nishi,H.,Moriya,K.,Wani,R.,andAndo,H.2004.GeologyandstratigraphyofforearcbasinsedimentsinHokkaido,Japan:CretaceousenvironmentaleventsonthenorthŠwestPacificmarTakashima,R.,Nishi,H.,Yamanaka,T.,Hayashi,K.,Waseda,A.,Obuse,A.,Tomosugi,T.,Deguchi,N.,andMochizuki,S.2010.HighŠresolutionterrestrialcarbonisotopeandplankticforaminiferalrecordsoftheUpperCenomaniantotheLowerCampanianintheNorthwestPacific.Tanabe,K.,Hirano,H.,Matsumoto,T.,andMiyata,Y.1977.StratigraphyoftheUpperCretaceousdepositsintheObiraarea,northwesternHokkaido[inJapanese,withEnglishabstract].MemoirsoftheFacultyof Science,Kyushu University, Series D, GeologyToshimitsu,S.,Hirano,H.,Matsumoto,T.,andTakahashi,K.2003.DataŠbaseandspeciesdiversityofJapaneseCretaceousammonoids.Uramoto,G.,Abe,Y.,andHirano,H.2009.CarbonisotopefluctuationsofterrestrialorganicmatterfortheUpperCretaceous(Cenomanian…Santonian)intheObiraareaofHokkaido,Japan.GeologicalMagazineUramoto,G.,Fujita,T.,Takahashi,A.,andHirano,H.2007.Cenomanian(UpperCretaceous)carbonisotopestratigraphyofterrestrialorganicmatterfortheYezoGroup,Hokkaido,Japan.IslandArc16:465…478.Voigt,S.,Gale,A.S.,andFlögel,S.2004.MidlatitudeshelfseasintheCenomanian…Turoniangreenhouseworld:TemperatureevolutionandWilson,P.A.,Norris,R.D.,andCooper,M.J.2002.TestingtheCretaceousgreenhousehypothesisusingglassyforaminiferalcalcitefromthecoreYazykova,E.2004.AmmonitebiozonationandlithoŠ/chronostratigraphyoftheCretaceousinSakhalinandadjacentterritoriesofFarEastRussia.KURIHARAETAL.„AMMONOIDSANDCENOMANIAN…TURONIANBOUNDARYINHOKKAI