Early and Middle Jurassic climate changes

GeophysicalResearchAbstracts

Vol.16,EGU2014-15944-1,2014

EGUGeneralAssembly2014

©Author(s)Attribution3.0License.

EarlyandMiddleJurassicclimatechanges:implicationsfor

palaeoceanographyandtectonics

ChristophKorte(1),StephenP.Hesselbo(2),ClemensV.Ullmann(1),MichaRuhl(3),andNicolasR.Thibault

(1)

(1)UniversityofCopenhagen,Denmark(korte@ign.ku.dk),(2)CamborneSchoolofMines,UniversityofExeter,UK,(3)UniversityofOxford,UK

Theoccurrenceof‘iceages’withintheoverallwarmJurassicPeriodhasbeenthesubjectofmuchcontroversy.Ithasbeensuggestedonthebasisofoccurrenceofglendonitesincircum-ArcticbasinsthatcoldepisodestookplaceintheJurassic(Price,1999;RogovandZakharov,2010).Herewepresentnewhigh-resolutionoxygenisotopedatasetsfrommarinecalciticfossilsofdifferentEuropeanbasinsthatindicatestrongtemperature uctuationsduringthePliensbachian-Bajociantimespan.ThealreadyreportedcoldLatePliensbachianepisodecomprisesatleastthreepronouncedoxygenisotope‘IceAge’cycles.ThesubsequentwellknownToarcianOceanicAnoxic‘supergreenhouse’EventisfollowedbyverywarmseawatertemperaturesinthelateToarcian.AverypronouncedcoolingoccurredduringthelatestToarciantoearlyAalenian(Early-MiddleJurassicBoundaryEvent).ThisepisoderesultedinsubstantialexpansionofArcticclimatestopalaeolatitudesaslowas45 andindistinctlycoolerseawatertemperaturesinlowerlatitudeEuropeanseas.WeproposethattheextensivecoolingattheEarly-MiddleJurassicBoundaryEventwasdrivenbysubstantialchangesinoceaniccurrentpatternsinitiatedbyupliftoftheNorthSeaDomepreventingthetransportofheattoPolarRegionsviatheVikingCorridor.

Literature

Price,G.D.(1999).TheevidenceandimplicationsofpolariceduringtheMesozoic,Earth-Sci.Rev.,48,183-210.

Rogov,M.A.,Zakharov,V.A.(2010).JurassicandLowerCretaceousglendoniteoccurrencesandtheirimplicationforArcticpaleoclimatereconstructionsandstratigraphy.EarthScienceFrontiers17,345-347.