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The role of climate, marine influence and sedimentation rates in late-Holocene estuarine evolution (SW Portugal)

2019-04Journal article Open access
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dc.contributor.authorCosta, Ana Maria
dc.contributor.authorFreitas, Maria da Conceicao
dc.contributor.authorLeira, Manel
dc.contributor.authorCostas, S.
dc.contributor.authorCosta, Pedro J. M.
dc.contributor.authorAndrade, Cesar
dc.contributor.authorBao, Roberto
dc.contributor.authorDuarte, Joao
dc.contributor.authorRodrigues, Aurora
dc.contributor.authorCachao, Mario
dc.contributor.authorAraujo, Ana Cristina
dc.contributor.authorDiniz, Mariana
dc.contributor.authorArias, Pablo
dc.date.accessioned2020-07-24T10:52:33Z
dc.date.available2020-07-24T10:52:33Z
dc.date.issued2019-04
dc.description.abstractEstuaries are sensitive to changes in global to regional sea level, to climate-driven variation in rainfall and to fluvial discharge. In this study, we use source and environmentally sensitive proxies together with radiocarbon dating to examine a 7-m-thick sedimentary record from the Sado estuary accumulated throughout the last 3.6 kyr. The lithofacies, geochemistry and diatom assemblages in the sediments accumulated between 3570 and 3240 cal. BP indicate a mixture between terrestrial and marine sources. The relative contribution of each source varied through time as sedimentation progressed in a low intertidal to high subtidal and low-energy accreting tidal flat. The sedimentation proceeded under a general pattern of drier and higher aridity conditions, punctuated by century-long changes of the rainfall regime that mirror an increase in storminess that affected SW Portugal and Europe. The sediment sequence contains evidence of two periods characterized by downstream displacement of the estuarine/freshwater transitional boundary, dated to 3570-3400 cal. BP and 3300-3240 cal. BP. These are intercalated by one episode where marine influence shifted upstream. All sedimentation episodes developed under high terrestrial sediment delivery to this transitional region, leading to exceptionally high sedimentation rates, independently of the relative expression of terrestrial/marine influences in sediment facies. Our data show that these disturbances are mainly climate-driven and related to variations in rainfall and only secondarily with regional sea-level oscillations. From 3240 cal. BP onwards, an abrupt change in sediment facies is noted, in which the silting estuarine bottom reaches mean sea level and continued accreting until present under prevailing freshwater conditions, the tidal flat changing to an alluvial plain. The environmental modification is accompanied by a pronounced change in sedimentation rate that decreased by two orders of magnitude, reflecting the loss of accommodation space rather than the influence of climate or regional sea-level drivers.
dc.description.sponsorshipFCT by Spanish Ministry of Science and Innovation [SFRH/BD/110270/2015, HAR2014-51830-P, HAR2011-29907-C03-00]
dc.description.sponsorshipFCTPortuguese Foundation for Science and Technology [PTDC/HISARQ/121592/2010]
dc.description.sponsorshipInstituto Dom Luiz-IDL [UID/GEO/50019/2013]
dc.description.versioninfo:eu-repo/semantics/publishedVersion
dc.identifier.doi10.1177/0959683618824768
dc.identifier.issn0959-6836
dc.identifier.issn1477-0911
dc.identifier.urihttp://hdl.handle.net/10400.1/14375
dc.language.isoeng
dc.peerreviewedyes
dc.publisherSage Publications Ltd
dc.subjectRelative sea-level
dc.subjectRiver discharge
dc.subjectAtlantic coast
dc.subjectPaleoclimate
dc.subjectDrought
dc.subjectRegion
dc.subjectValley
dc.subjectField
dc.subjectFlow
dc.titleThe role of climate, marine influence and sedimentation rates in late-Holocene estuarine evolution (SW Portugal)
dc.typejournal article
dspace.entity.typePublication
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/5876/UID%2FGEO%2F50019%2F2013/PT
oaire.citation.endPage632
oaire.citation.issue4
oaire.citation.startPage622
oaire.citation.titleHolocene
oaire.citation.volume29
oaire.fundingStream5876
person.familyNameCostas
person.givenNameSusana
person.identifier1448818
person.identifier.ciencia-idAF19-9EEE-7550
person.identifier.orcid0000-0002-4005-077X
person.identifier.scopus-author-id9043656500
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsrestrictedAccess
rcaap.typearticle
relation.isAuthorOfPublication62d73183-10ba-42ca-80a7-458c42d1375b
relation.isAuthorOfPublication.latestForDiscovery62d73183-10ba-42ca-80a7-458c42d1375b
relation.isProjectOfPublication89f544c0-4cfb-44ea-8535-fa0719f73c4a
relation.isProjectOfPublication.latestForDiscovery89f544c0-4cfb-44ea-8535-fa0719f73c4a

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