Palynology and micropalaeontology of the Pliocene - Pleistocene transition in outcrop from the western Caspian Sea, Azerbaijan: Potential links with the Mediterranean, Black Sea and the Arctic Ocean?

TLDR: In this article, a long outcrop section in the Jeirankechmez river valley, Azerbaijan, near the western coast of the Caspian Sea has been studied, including the upper part of the Pliocene Productive Series and overlying Plio-Pleistocene Akchagylian and Apsheronian regional stages.

About: This article is published in Palaeogeography, Palaeoclimatology, Palaeoecology.The article was published on 2018-12-15 and is currently open access. It has received 33 citations till now. The article focuses on the topics: Dinocyst & Foraminifera.

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PalynologyandmicropalaeontologyofthePliocene‐Pleistocenetransitioninoutcropfromthe
westernCaspianSea,Azerbaijan:potentiallinkswiththeMediterranean,BlackSeaandtheArctic
Ocean?

By:KeithRichards
a,b,*
,ChristiaanG.C.vanBaak
c,d
,JohnAthersuch
e
,ThomasM.Hoyle
c,f
,Marius
Stoica
g,c
,WilliamE.N.Austin
h
,AlixG.Cage
i
,AntoineA.H.Wonders
e
,FabienneMarret
j
,CarmelA.
Pinnington
j



a
KrAStratigraphicLtd.,UnitedKingdom;
b
InstituteforBiodiversityandEcosystemDynamics(IBED),
UniversityofAmsterdam,TheNetherlands;
c
PaleomagneticLaboratory‘FortHoofddijk’,Utrecht
University,TheNetherlands;
d
nowat:CASP,Cambridge,UnitedKingdom;
e
StrataDataLtd.,United
Kingdom;
f
MarinePalynologyandPaleoceanography,UtrechtUniversity,TheNetherlands;
g
DepartmentofGeology,UniversityofBucharest;
h
SchoolofGeographyandGeosciences,University
ofStAndrews,UnitedKingdom;
i
SchoolofGeography,GeologyandtheEnvironment,Keele
University,UnitedKingdom;
j
SchoolofEnvironmentalSciences,UniversityofLiverpool,United
Kingdom.

*Correspondingauthorat:KrAStratigraphicLtd.,116AlbertDrive,Deganwy,Conwy,LL319YY,
UnitedKingdom.
Emailaddress:kr@paly.co.uk(K.Richards)

Abstract
Newpalynological,ostracodandforaminiferaldataarepresentedfromalongoutcropsectioninthe
Jeirankechmezrivervalley,Azerbaijan,nearthewesterncoastoftheCaspianSea.Theinterval
studiedincludestheupperpartofthePlioceneProductiveSeriesandoverlyingPlio‐Pleistocene
Akchagylian(Akchagyl)andApsheronian(Apsheron)regionalstages.ProductiveSeriessediments
weredepositedinaclosedfluvio‐lacustrinebasin,isolatedfromanymarineinfluence.Theonsetof
Akchagyldepositionismarkedbyalithologicalchangeassociatedwithasignificantfloodingevent
that,atitsmaximumextent,reachedtheSeaofAzovandintopresent‐dayIran,Kazakhstan,
TurkmenistanandRussia.AttheJeirankechmezlocality,thelowermostbedsoftheAkchagylcontain
predominantlyfreshwaterassemblageswithveryminimalmarineorbrackishcontentshowingthat
theonsetofAkchagyldepositionwasnotamarineinducedevent.ReworkedMesozoic
palynomorphsoccurfrequentlyinthislowermostinterval,includingthereworkedpollentaxa
Aquilapollenites‐Triprojectusthatwereerodedfromthenorthornorth‐east.
 Significantmarineinfluenceisevidentca.30mabovethebaseoftheAkchagylinthestudied
outcrop,markedbythe‘CassidulinaBeds’whichcontainadistinctbutlowdiversityassemblageof
foraminiferathatoccurswidelyandcanbecorrelatedinmanypartsofthegreaterCaspianregion.
Dinoflagellatecysts(dinocysts)inthemarineintervalincludefrequentspecimensverysimilarto
Algidasphaeridiumcapillatum(MatsuokaandBujak),aspeciesonlypreviouslyrecordedfromthe
northernBeringSea.Thecombinedevidencefromthesedinocystsandforaminiferasuggeststhata
marine(i.e.seaway)connectionexistedbrieflybetweentheArcticOceanandtheCaspianSeaatthe
veryendofthePliocene.
Re‐examinationofcorematerialfromtheAdriaticSeashowsthatCassidulinareniforme
(Nørvang)waspresentintheMediterraneanduringandshortlyaftertheLastGlacialMaximum.The
possibilitythattheendPliocenemarineincursioncamefromtheMediterraneanviatheBlackSea
regiontotheCaspianSeacannotbeentirelyruledoutbutisconsideredunlikely.Biometricanalyses
areappliedtoobtainabetterunderstandingofthepalaeoenvironmentalsignificanceofthe
assemblagesdominatedbycassidulinids.
 Anintervalmorethan300mthickisassignedtotheApsheronregionalstageonthebasisof
predominantlybrackishostracodanddinocystassociations.Thedinocystsareof‘Peri‐Paratethyan’
affinityandcloselyresemblespeciesfirstdescribedfromMioceneandPliocenesedimentsinthe

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PannonianandDacicbasinsofEasternEurope.Manysimilaritiesexistinthemicroplanktonrecords
(dinocystsandacritarchs)betweentheCaspianSea,theBlackSeaandCentralParatethys.

Keywords
Akchagyl;Apsheron;Dinoflagellatecysts;Pollen;Ostracods;Foraminifera

1. Introduction
TheCaspianSeaisthelargestlakeintheworldbyvolumeandsurfacearea(Dumont,1998).Itisina
constantstateofflux,withfluctuationsinwaterlevelintheorderof100sofmetersoccurring
throughoutthePleistocene(Svitoch,2014;Yanina,2013).Becauseoftherelativelyflattopographyin
thenorthernCaspianregion,waterlevelhighstandsareassociatedwithenormousexpansionsofthe
sea‐surfacearea.Thelargestsea‐surfaceareaoftheCaspianSeainthePlio‐Pleistocenewasachieved
duringtheAkchagylregionalstage(MolostovskyandGuzhikov,1999;Nevesskayaetal.,2003),
beginningaroundthreemillionyearsagointhelatestPlioceneandcontinuingintotheearly
Pleistocene.Thistransgressionwasparticularlysignificantinthatitoccurredfollowingaperiod,
lastingmorethantwomillionyears,whentheCaspianBasinwasisolatedfromtheworld’soceans
andnon‐marine,fluvio‐lacustrinedepositionoftheProductiveSeriesoccurred,predominantlyinthe
deeperSouthCaspianBasin(Reynoldsetal.,1998;Hindsetal.,2004;Forteetal.,2015).Later
expansionsduringtheApsheronandyoungerPleistoceneregionalstagesneverstretchedasfar
inlandasduringthemaximumAkchagyltransgression(Svitoch,2014).
Akchagylsedimentsaregenerallydescribedasmarineandinmostaccounts(e.g.Jonesand
Simmons,1996;Svitoch,2014)arepresumedtohaveoriginatedfollowingariseinglobalsealevels
duringthelatePliocenethatraisedtheleveloftheMediterraneanSea,thatsubsequentlyflooded
theBlackSeaandthenover‐spilledintotheCaspianSeatothenorthoftheCaucasus.Anopposite
viewisheldbyZubakov(e.g.1992)whoconsidersthatCaspiantransgressions,includingthe
Akchagylian,resultfromincreasedriverrunoff,particularlyfromtheVolga,withsubsequentover‐
spillfromtheCaspianSeatoadjacentbasins,includingtheBlackSea.Irrespectiveoftheoriginofthe
initialriseinCaspianwaters,thereisundoubtedlysomedirectmarineinfluenceintheLowerto
MiddleAkchagyl,andthisismostevidentintheso‐called‘CassidulinaBeds’thathavebeen
documentedinpreviousbiostratigraphicstudiesfromAzerbaijanandelsewhere.Thesebedsare
described(e.g.Agalarovaetal.,1940;Mandelstametal.,1962;Yassini,1986;JonesandSimmons,
1996)ascontaininganinfluxofcalcareousbenthonicforaminifera,mostoftenincludingspeciesof
CassidulinaandCibicides,includingC.lobatulus(WalkerandJacob).Previouspalynologicalstudiesof
thelatePliocenetoearly/middlePleistoceneoftheCaspianSearegion(e.g.Filippova,1997;
Naidina,1999;Yakhimovichetal.,2000;NaidinaandRichards,
2016)areessentiallypollenandspore
based.These,therefore,givelimitedinterpretationsinthatinferredenvironmentalorclimatic
changesarebasedonlyonterrestrialvegetation.
ThesedimentsoverlyingtheAkchagylaremostoftenreferredtoastheApsheronregional
stageandthesearewidelydepositedacrossAzerbaijan(AliyevaandKengerli,2014)andthewider
Caspianregion(Abdullayevetal.,2012).DepositionoftheApsheronoccurredduringtheearly
PleistoceneinaclosedbrackishwaterbasinresemblingthemodernCaspianSeaaccordingtoSvitoch
(2014).HerewestudytheAkchagylandApsheronfossilfaunas(ostracodsandforaminifera)and
floras(dinoflagellatecysts,pollenandotherpalynomorphs)inalongandcontinuouslyexposed
outcroprecordintheJeirankechmezRiverValley,GobustanregionofAzerbaijan(Fig.1).Theaimof
thestudyistodocumentthefaunalandfloralchangesthatoccurredinresponsetovariationsin
palaeoenvironmentalconditionsassociatedwiththeAkchagyltransgressionoftheCaspianSeaand
subsequentApsherondeposition.TheseeventsoccurredduringthelatestPliocenetoearly
Pleistocene,atthetimeoftheonsetofnorthernhemisphereglaciations.Biostratigraphicmethods
areusedtodifferentiatetheAkchagylandApsheronintervalsduetothelackofmolluscfaunaand
absenceofaclearlydefinedlithologicalboundary.Comparisonsofmicrofaunaldataaremadewith

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publishedrecordsfromtheArcticOceanandwithnewlyobtainedforaminiferaldatafromacoreof
latePleistoceneagefromtheAdriaticSea.

2. Regionalstagenomenclatureandpreviousmicropalaeontologicalstudies
AlongresearchhistoryofmicropalaeontologicalandstratigraphicstudiesoftheAkchagyland
Apsheronstagesexists,datingbacktothe19
th
century.Thename‘Akchagyl’isderivedfromthe
nameofalocalityinthecoastalregionofTurkmenistan(JonesandSimmons,1996).Sediments
attributedtotheAkchagylregionalstageinAzerbaijanwerefirstdescribedbyAndrusov(1902)and
sincethenhavebeenthesubjectofmuchstudyanddebate(seeJonesandSimmons,1996;Alizadeh
etal.,2016forfurtherdetails).AkchagylsedimentsarewidespreadthroughoutmostoftheCaspian
regionandextendbeyondthepresent‐dayCaspianSeaareaeastwardsintoKazakhstanand
Turkmenistan(Alizadeh,1961;Danukalova,1996;Trubikhin,1977),westwardsintoAzerbaijanand
Georgia(Agalarovaetal.,1961;Shatilovaetal.,2009),tothenorthintoRussia(Yakhimovichetal.,
2000;Svitoch,2014)andtothesouthintoIran(Yassini,1986).Notsurprisingly,thefaunalcontent
variessignificantlyacrosstheregion,leadingtoproblemsincorrelationofmicrofaunalassemblages
andchronostratigraphiccalibrations.Additionalcomplicationshavearisenbyusingtheoriginal
biostratigraphicallydefinedAkchagylstageasalithostratigraphicunit.Assuch,alargenumberof
differentdefinitionsofboundariesandsub‐divisionshavebeenproposedovertime.Itisclearfrom
theoverlappingandvariablenatureoftheseassemblagesthatthetruerelationshiprelativeto
lithostratigraphicunits,andalsotime,remainsopentoquestion.AccordingtotheRussian
chronostratigraphicschemes,Akchagylsedimentsarenotolderthanca.3.60Maandnotyounger
thanca.1.80Ma(Trubikhin,1977)andthereforefallwithinthelatePliocene(Piacenzian)toearly
Pleistocene(Gelasian)andtheGaussandMatuyamamagneticchrons(seeAlizadehetal.,2016;Van
Baaketal.,2013forfurtherdetails).
 Akchagylsedimentstypicallycomprisegrey,dark‐greyandgrey‐bluesandyclays,andfineto
medium‐grainedsands,sandstonesandshellbeds(Alizadehetal.,2016).Interbedsofvolcanicash
andbrecciaalsooccur.AccordingtoAliyevaandKengerli(2014),themud‐proneLowerAkchagyl
typicallycontainsfreshwaterostracods,withCyprideistorosa(Jones),abrackishform,predominant
inthemore‐sandyMiddleAkchagyl.TheUpperAkchagylcharacteristicallycomprisesalternatinggrey
andbrownsandyshaleswithinterbedsofsandstoneandvolcanicash,andcontainsmainlybrackish
waterostracods.ThelowerboundaryoftheAkchagylisdefinedbytheappearanceof‘poormarine
fauna’(Danukalova,1996;Molostovsky,1997;Alizadehetal.,2016)whichincludestheforaminifera
CibicidesandCassidulina,andmolluscsAvimactrasubcaspia(Andrussov),Cardium(Cerastoderma)
dombra(Andrussov),Cerastodermaglaucum(Bruguière)andPotamides(Pirenella).Detailed
descriptionsofthemolluscfaunasarepresentedbyNevesskayaetal.(1987,2001)amongothers.
 Athree‐foldsub‐divisionfortheAkchagylinthenorthernCaspianregionisoftenused(e.g.
NaidinaandRichards,2016)butisnotaccuratelytime‐constrained.Typicalmicrofaunalassociations
aredescribedbySvitoch(2014),referringtoearlierworkbyKarmishina(1964)andothers.Following
theschemeofSvitoch(2014),thelowermostAkchagyl(Ak
1
)containsforaminiferasuchasBolivina,
CassidulinaandElphidiumaswellastheostracodgeneraLeptocythere,Loxoconcha,Limnocythere
andCandona.TheMiddleAkchagyl(Ak
2
)containstherichestmicrofaunalassemblageswith
increasednumbersofforaminiferaandostracodsobserved.Marinefaunabecomediminishedonce
againintheUpperAkchagyl(Ak
3
)whereostracodspredominate,includingCyprideislittoralis(Brady)
(=C.torosaaccordingtoKempf,2017),Limnocytherepliocenica(Suzin),L.tenuireticulata(Suzin)and
Eucytherenaphtatscholana(Livental),interpretedasaresponsetoreducedsalinity.Svitoch(2014)
assignsthePlio‐Pleistocene(2.58MaGauss‐Matuyama)boundarywithintheMiddleAkchagyl(Ak
2
).
InthecentralandsouthernregionsoftheCaspianregion,Rozyeva(1966),referringto
Alizadeh(1961),alsoindicatedthatathree‐foldsub‐divisionoftheAkchagylFormationwaspossible
onthebasisofostracodsinTurkmenistan.NumerousspeciesofCandonaandLimnocytherewere
recordedfromthelowersub‐division.Inaddition,theforaminiferaCassidulinaandCibicides
lobatuluswererecorded.TheseforaminiferawerefirstrecordedintheLowerAkchagylbyAgalarova


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
etal.(1940)andhavesubsequentlybeenfoundinmanylocalitiesinthegreaterCaspianregion(e.g.
Yassini,1986;Alizadehetal.,2016).Rozyeva(1966)describesthemiddlesub‐divisionoftheAkchagyl
inTurkmenistanasbeingthinandpoorlyfossiliferous,andtheuppersub‐divisionasbeing
characterisedbynumerousspeciesrecordedasLeptocythere(whichdonotoccurbelow)andby
Loxoconchaeichwaldii(Livental),Cytherissa(=Eucythere)naphtatscholanaaswellasundifferentiated
speciesofLimnocythereandCandona.ForAzerbaijan,Mandelstametal.(1962)presentedasimilar
sub‐divisionbasedonostracods.Theseauthorsformalisedthesub‐divisionsintoalowerEucypris
puriformiszone,amiddleunnamedintervalandanupperLeptocytherezone.Itisalsointerestingto
notethatacomparableLoxoconcha‐Leptocythere‐Cytherissa‐Limnocythereassemblageisdescribed
bySvitoch(2014)butattributedtotheApsheronratherthanAkchagyl.TheApsheronregionalstage
istypicallyrecognisedbiostratigraphicallybytheincomingofa‘Ponto‐Caspian’endemicmollusc
fauna,whichincludesthegeneraApsheronia,Dreissena,Hyrcania,Monodacna,Paraapsheroniaand
Pseudocatillus,amongothers(Molostovsky,2007;Svitoch,2014).

3.Sectiondescription
Thedatausedinthisstudyarederivedfromacontinuousoutcropofca.1600minthicknessexposed
alongtheJeirankechmezRiver,intheGobustanregionofAzerbaijan,around50kmtothesouth‐
westofBaku.Thebaseofthesectionislocatedatgridpoint40.237771°N,49.365299°E.The
lowermostpartofthestudiedsectionconsistsofmorethan750moffluvio‐deltaicsandstonesand
brown,siltyclaysofthePlioceneProductiveSeries.Thisisoverlainbyanintervalofmorethan800m
oflight‐greyandyellow‐brownmarlsthat,basedonfieldcharacteristics,areattributedtothe
AkchagylandApsheronregionalstages.Thereis,however,noobviousstratigraphicbreakvisible
withintheoutcropthatcanbeusedtoassigntheAkchagyl‐Apsheronboundary.Organic‐rich
(sapropel)layersofupto1mthickoccuratthreelevels;897m,940mand990m(Fig.2).Initialfield
observationsindicatedthatthestudyoutcropcontainedveryfewfossilmolluscs.Palynologyand
micropalaeontologywerethereforechosenasthepreferredmethodsofbiostratigraphicstudy.

4.Materialsandmethods
Sixtyfoursampleswereanalyzedformicrofossils(primarilyostracodsandforaminifera)and
palynologyfromtheAkchagyl(includingtheboundarywiththeunderlyingProductiveSeries)and
presumedApsheronintervalsoftheoutcropsectionatJeirankechmez.Samplesdescribedinthis
studyarefromanintervalaround375mthick.Averagespacingofsamplesovertheentireintervalis
approximatelyonesamplepersixmetres.Ingeneral,studiedsamplesaremorecloselyspacedinthe
lower(Akchagyl)intervalandmorewidelyspacedintheupper(Apsheron)interval.Afterinitial
resultswereobtained,additionalinfillsampleswereanalysedoverspecificintervalsofinterest.
Samplesreferredtointhetextareindicatedbytheirrelativestratigraphicposition(i.e.elevationin
metres)withintheoutcrop,followedbythesamplereference(e.g.1140.98m,JE146).Anadditional
sampleLOK2wasstudiedfromtheLokbatanlocality,situatedca.20kmtothenorth‐east,nearBaku,
ontheApsheronpeninsula.Foraminiferalresultsarecomparedwithpreviouslyunpublisheddata
fromgravitycoreJM10‐03‐GC,takenatWijdefjorden,northernSvalbardandfromcoreIN68‐21
collectedintheAdriaticSea.
Formicrofossils,eachsamplewaswashed througha125µmsieveandtheresiduedriedat
100°Cwithquantitativecountsthenmadeofeachspecies.Identificationsandenvironmental
interpretationsforostracodsarebasedonnumeroussourcesincludingAgalarovaetal.(1961),
Athersuchetal.(1989),Boomeretal.(2005,2010),Mandelstametal.(1962),Meisch(2000),Van
Baaketal.(2013),Stoicaetal.(2016)andDaniel(2013).
SamplesforpalynologywereprocessedwithoutoxidationusingcoldHCl(20%)andcoldHF
(40%)withresiduessievedusing10µmmeshsievecloth.Countsweremadeofallpalynomorphsi.e.
pollengrains,spores,algae,non‐pollenpalynomorphs(NPP)anddinocysts,includingreworkedtaxa.A
minimumsumof200palynomorphswasobtainedinmostcases,exceptwherepalynomorphrecovery
wasmuchreducedinsandyorotherwiseless‐fossiliferouslithologies.Pollenidentificationswere

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
madeprimarilywithreferencetonorth‐westEuropeanandRussianpollenfloras(e.g.Bobrovetal.,
1983;KuprianovaandAlyoshina,1972,1978).DinocystsandNPPwereidentifiedfromnumerous
sourcesincludingBakračetal.(2012),Baltes(1971),Evittetal.(1985),Marretetal.(2004),Mudieet
al.(2011),Mudieetal.(2017,2018),Richardsetal.(2014,2017),SolimanandRiding(2017),Sütő‐
Szentai(1982,2010,2011)andWalletal.(1973).
Biostratigraphiczonationsare,inmostinstances,supportedbyCONISSclusteranalysis
(Grimm,1987)usingStrataBugs®v.2.1.Duetoproblemsinherentfromsomesamplesbeingbarrenof
microfaunaorcontainingveryimpoverishedassemblages,zonesareassignedbyacombinationof
observeddistributionsandreferencetotheirassignedclusters.TheCONISSclusteranalyseswere
carriedoutontheentiremicropalaeontological(i.e.ostracodsandforaminiferacombined)and
palynologicaldatasets.Clusteringwasstratigraphicallyconstrainedinordertodetermine,asfaras
possible,eventsofbiostratigraphicvalue.Barrenorverypoorlyfossiliferoussamplesareexcluded
fromtheclusteranalysisofmicrofaunaldataandfromzoneassignments.
FortheSEMpalynologicalpreparations,approximately0.5mlofresiduewasmixedwith
distilledwaterinaplasticPetridish.Specimenswereisolatedwithaglassmicropipetteusingan
invertedmicroscopeandwashedindistilledwater.Cleanspecimenswerethenmountedona
Cambridgealuminiumstubandsputtercoatedwithgold/palladium(PolaronE5100).Specimensof
ostracodsandforaminiferaselectedforSEMpreparationswerehand‐pickedfromdriedprocessed
residues.

5.Micropalaeontologyresults
Sixdistinctintervalscanberecognisedinthestudiedsectionbasedonmicrofauna(ostracodsand
foraminifera)(Fig.3).TheseareassignedasZonesJM(JM=JeirankechmezMicrofauna)1to6,which
coincidewithCONISSclustersinalmostallcases.SamplesstudiedfromtheProductiveSeries
(assignedasZoneJM‐1)weremostlypoorlyfossiliferousandoflittleinterpretivevalue,exceptfor
thepresenceofasinglespecimenoftheostracodCyprideistorosaandasparse,reworked
foraminiferalassemblage.ZonesJM2to6occurwithintheAkchagyltoApsheronintervalsandare
describedbelow.Adistributionchartshowingallmicrofaunarecordedareprovidedas
supplementaryinformation.RepresentativeSEMphotomicrographsofmicrofaunaareshownin
Figure4(foraminifera)andFigures5,6,and7(ostracods).Theillustrationsofostracodsareof
specimensfromaduplicatesetofsamplesandthereforecontainsomespecieswhichwerenot
identifiedintheprincipalsectionanalysed.NannofossilanalysisofsampleJE039(797.88m)yielded
anentirelyreworkednannoplanktonassemblagelackinginaclearbiostratigraphicsignal(Table1).
5.1.ZoneJM‐2:770.58m(JE028)–789.83m(JE036)
OstracodassemblagesarecharacterisedbythepresenceofLimnocythere,includingL.alveolata
(Suzin)andL.luculenta(Livental).AfewjuvenilespecimensofEucytherenaphtatscholanawere
recoveredfromonesampleonly(774.48m,JE030).Otherwise,theassemblagescontain
undifferentiatedspeciesofLoxoconcha,candonidsandvarioussmoothostracods.Rarecalcareous
benthonicforaminiferawererecordedincludingAmmonia(774.48m,JE030;789.83m,JE036),
ElphidiumandSpirillina(bothat789.83m,JE036).Fiveofthestudiedsamplescontainedno
microfauna.

5.2.ZoneJM‐3
5.2.1.Sub‐zoneJM‐3A:797.88m(JE039)–813.18m(JE045)
Limnocythere,includingthesupposedlyAkchagylrestrictedL.tschaplyginae(Suzin)andLoxoconcha
(includingrareL.eichwaldii)arepresentatthebaseoftheinterval.Undifferentiatedsmooth
ostracodsandfragmentsofvalvesalsooccur.Themainfeatureofthisintervalisthesignificantly
increasedpresenceofbenthicforaminiferaparticularlyspeciesofCassidulinainassociationwith
Cibicides(includingseveralmorphotypes/sub‐species)andHanzawaia.Thisassemblageispresentin
mostsamplesstudiedbetween797.88m(JE039)and813.18m(JE045).Otherbenthicforaminifera

Frequently asked questions

Q1. What are the contributions in this paper?

The interval studied includes the upper part of the Pliocene Productive Series and overlying Plio‐Pleistocene Akchagylian ( Akchagyl ) and Apsheronian ( Apsheron ) regional stages. Reworked Mesozoic palynomorphs occur frequently in this lowermost interval, including the reworked pollen taxa Aquilapollenites‐Triprojectus that were eroded from the north or north‐east. Significant marine influence is evident ca. 30 m above the base of the Akchagyl in the studied outcrop, marked by the ‘ Cassidulina Beds ’ which contain a distinct but low diversity assemblage of foraminifera that occurs widely and can be correlated in many parts of the greater Caspian region. The combined evidence from these dinocysts and foraminifera suggests that a marine ( i. e. seaway ) connection existed briefly between the Arctic Ocean and the Caspian Sea at the very end of the Pliocene.