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Absence of a strong, deep-reaching Antarctic Circumpolar Current zonal flow across the Tasmanian gateway during the Oligocene to early Miocene

dc.rights.licenseopenen_US
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorEVANGELINOS, Dimitris
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorESCUTIA, Carlota
dc.contributor.authorVAN DE FLIERDT, Tina
dc.contributor.authorVALERO, Luis
dc.contributor.authorFLORES, Jose-Abel
dc.contributor.authorHARWOOD, David M.
dc.contributor.authorHOEM, Frida S.
dc.contributor.authorBIJL, Peter
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorETOURNEAU, Johan
dc.contributor.authorKREISSIG, Katharina
dc.contributor.authorNILSSON-KERR, Katrina
dc.contributor.authorHOLDER, Liam
dc.contributor.authorLOPEZ-QUIROS, Adrian
dc.contributor.authorSALABARNADA, Ariadna
dc.date.accessioned2023-11-06T11:14:05Z
dc.date.available2023-11-06T11:14:05Z
dc.date.issued2022-01-01
dc.identifier.issn0921-8181en_US
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/184611
dc.description.abstractEnThe vigorous eastward flow of the Antarctic Circumpolar Current (ACC) connects all major ocean basins and plays a prominent role in the transport of heat, carbon and nutrients around the globe. However, the establishment of a deep circumpolar flow, similar to the present-day ACC, remains controversial thereby obscuring our understanding of its climatic impact. Deciphering the chemical composition of Circumpolar Deep Water (CDW) within the ACC can provide critical insights about its development and evolution. Here we present new fossil fish teeth/bone debris neodymium isotope (εNd) records from Deep Sea Drilling Project (DSDP) Sites 278 and 274 in the southwest Pacific Ocean, with the aim to trace changes in deep water masses across the Tasmanian Gateway between the early Oligocene and early Miocene (~ 33–22 Ma). Site 274 provides the first Nd isotope record proximal to the Ross Sea during the Oligocene (33.5–23.4 Ma). Its Nd isotope composition shows excursions to very radiogenic values, εNd(t) = −3.1 and εNd(t)= − 3.7, at 33.5 Ma and 23.8 Ma, respectively, in response to major steps in Antarctic ice sheet expansion. A shift to lower, more unradiogenic εNd(t) values between 29.7 and 29.1 Ma is linked to an increased influence of proto-CDW upwelling at the site. In contrast, the Nd isotope record from Site 278 in the southern Emerald Basin shows little variability (εNd(t) = −6.0 to −6.7) throughout the Oligocene and early Miocene (30.9–21.8 Ma). Comparison with published data north of the ACC path, demonstrates the presence of two deep water masses in the South Pacific prior to the inferred onset of the ACC (33–30 Ma), one occupying depths between ~2500 and 3000 m (εNd(t)= ~ −3 to −5) and a deep/bottom water mass (> 3000 m) with a more unradiogenic Nd isotope composition (εNd(t)= ~ −6). Site 278 located close to the proto-polar front (proto-PF) indicates that following the inferred onset of the ACC, deep waters bathing the southern Emerald Basin remained more radiogenic in the Southwest Pacific compared to sites along the proto-PF in the South Atlantic and Indian Ocean (εNd(t)= ~ −8.1). This indicates a provinciality in Nd isotope compositions of deep waters along the proto-PF across the Tasmanian Gateway. Our data are incompatible with the existence of a modern-like homogenous (lateral and vertical) Nd isotope composition of CDW along the main flow path of the ACC in all oceanic basins in the Oligocene to early Miocene. We attribute distinct Nd isotope compositions of deep waters across the Tasmanian Gateway to reflect a less deep reaching and weaker ACC (proto-ACC) than today. Our findings suggest that the modern strong and deep-reaching ACC flow must have been developed at a later point in the Neogene.
dc.language.isoENen_US
dc.title.enAbsence of a strong, deep-reaching Antarctic Circumpolar Current zonal flow across the Tasmanian gateway during the Oligocene to early Miocene
dc.title.alternativeGlobal and Planetary Changeen_US
dc.typeArticle de revueen_US
dc.identifier.doi10.1016/j.gloplacha.2021.103718en_US
dc.subject.halSciences de l'environnementen_US
bordeaux.journalGlobal and Planetary Changeen_US
bordeaux.volume208en_US
bordeaux.hal.laboratoriesEPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805en_US
bordeaux.institutionUniversité de Bordeauxen_US
bordeaux.institutionCNRSen_US
bordeaux.teamPALEOen_US
bordeaux.peerReviewedouien_US
bordeaux.inpressnonen_US
hal.popularnonen_US
hal.audienceInternationaleen_US
hal.exportfalse
dc.rights.ccPas de Licence CCen_US
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Global%20and%20Planetary%20Change&rft.date=2022-01-01&rft.volume=208&rft.eissn=0921-8181&rft.issn=0921-8181&rft.au=EVANGELINOS,%20Dimitris&ESCUTIA,%20Carlota&VAN%20DE%20FLIERDT,%20Tina&VALERO,%20Luis&FLORES,%20Jose-Abel&rft.genre=article


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