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The nature of opal burial in the equatorial atlantic during the deglaciation

dc.contributor.authorGil, Isabelle M.
dc.contributor.authorMcManus, J. F.
dc.contributor.authorRebotim, Andreia
dc.contributor.authorNarciso, A.
dc.contributor.authorSalgueiro, Emilia
dc.contributor.authorAbrantes, Fatima
dc.date.accessioned2023-10-02T13:59:50Z
dc.date.available2023-10-02T13:59:50Z
dc.date.issued2023
dc.description.abstractRelatively high opal concentrations are measured in equatorial Atlantic sediments from the most recent deglaciation. To shed light on their causes, seven cores were analyzed for their content of siliceous (diatom, silicoflagellates, radiolarians, phytoliths, and sponge spicules) and calcareous (coccolithophores) microfossils. An early deglacial signal is detected at the time of rising boreal summer insolation ca. 18 ka by the coccolithophores. The surface freshening is likely due to the rain belt associated with the intertropical convergence zone (ITCZ), implying its southward shift relatively to its present-day average positioning. The diatom assemblages corresponding to the following increase in diatom abundances ca. 15.5 ka suggest the formation of a cold tongue of upwelled water associated with tropical instability waves propagating westward. Such conditions occur at present during boreal summer, when southerly trade winds are intensified, and the ITCZ shifts northward. The presence of the diatom Ethmodiscus rex (Wallich) Hendey and the coccolithophore Florisphera profunda indicates a deep thermocline and nutrient enrichment of the lower photic zone, revealing that Si-rich southern sourced water (SSW) likely contributed to enhanced primary productivity during this time interval. The discrepancies between the maximum opal concentrations and siliceous marine microfossils records evidence the contribution of freshwater diatoms and phytoliths, indicative of other processes. The definition of the nature of the opal record suggests successive productivity conditions associated with specific atmospheric settings determining the latitudinal ITCZ positioning and the development of oceanic processes; and major oceanic circulation changes permitting the contribution of SSW to marine productivity at this latitude.pt_PT
dc.description.sponsorshipLA/P/0101/2020pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.doi10.1029/2022PA004582pt_PT
dc.identifier.eissn2572-4517
dc.identifier.urihttp://hdl.handle.net/10400.1/20027
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherAmerican Geophysical Unionpt_PT
dc.relationStrategic Project - LA 15 - 2011-2012
dc.relationAlgarve Centre for Marine Sciences
dc.relationAlgarve Centre for Marine Sciences
dc.relationCOMBINING PALEO-DATA AND CLIMATE MODELLING TO UNDERSTAND A SHIFT TO A WARMER CLIMATE: A CASE STUDY FROM THE LAST DEGLACIATION IN THE NORTH ATLANTIC
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/pt_PT
dc.subjectSilica leakage hypothesispt_PT
dc.subjectDiatompt_PT
dc.subjectDeglaciationpt_PT
dc.subjectAtlantic Oceanpt_PT
dc.titleThe nature of opal burial in the equatorial atlantic during the deglaciationpt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.awardTitleStrategic Project - LA 15 - 2011-2012
oaire.awardTitleAlgarve Centre for Marine Sciences
oaire.awardTitleAlgarve Centre for Marine Sciences
oaire.awardTitleCOMBINING PALEO-DATA AND CLIMATE MODELLING TO UNDERSTAND A SHIFT TO A WARMER CLIMATE: A CASE STUDY FROM THE LAST DEGLACIATION IN THE NORTH ATLANTIC
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/5876-PPCDTI/PTDC%2FAAC-AMB%2F108449%2F2008/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/6820 - DCRRNI ID/PEst-C%2FMAR%2FLA0015%2F2011/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB%2F04326%2F2020/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDP%2F04326%2F2020/PT
oaire.awardURIinfo:eu-repo/grantAgreement/FCT//SFRH%2FBPD%2F87718%2F2012/PT
oaire.citation.issue8pt_PT
oaire.citation.titlePaleoceanography and Paleoclimatologypt_PT
oaire.citation.volume38pt_PT
oaire.fundingStream5876-PPCDTI
oaire.fundingStream6820 - DCRRNI ID
oaire.fundingStream6817 - DCRRNI ID
oaire.fundingStream6817 - DCRRNI ID
person.familyNameGil
person.familyNameRebotim
person.familyNameSalgueiro
person.familyNameAbrantes
person.givenNameIsabelle
person.givenNameAndreia
person.givenNameEmilia
person.givenNameFatima
person.identifier.ciencia-idD815-9890-8017
person.identifier.ciencia-id7511-A470-FA40
person.identifier.ciencia-id3B10-07FD-161C
person.identifier.ciencia-id021D-CA76-20D2
person.identifier.orcid0000-0001-5151-2258
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person.identifier.orcid0000-0003-1000-2977
person.identifier.orcid0000-0002-9110-0212
person.identifier.ridG-1019-2013
person.identifier.ridB-5985-2013
person.identifier.scopus-author-id15727594300
person.identifier.scopus-author-id56829454800
person.identifier.scopus-author-id23486371200
person.identifier.scopus-author-id16030759200
project.funder.identifierhttp://doi.org/10.13039/501100001871
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project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT
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