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| Titel |
An annually-resolved palaeoenvironmental archive for the Eastern Boundary North Atlantic upwelling system: Sclerochronology of Glycymeris glycymeris (Bivalvia) shells from the Iberian shelf |
| VerfasserIn |
Pedro Freitas, Carlos Monteiro, Paul Butler, David Reynolds, Christopher Richardson, Miguel Gaspar, James Scourse |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110238
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| Publikation (Nr.) |
 EGU/EGU2015-10215.pdf |
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| Zusammenfassung |
| The seasonally variable western Iberia upwelling system, albeit placed at a crucial
climatic boundary position to record high frequency climate events, lacks well-dated
high-resolution records of environmental variability. Bivalve shells provide robust
high-resolution archives of oceanographic and climatic variability on timescales of
decades to millennia. In particular, the North Atlantic Ocean region has recently seen
several noteworthy sclerochronological and geochemical reconstructions based
on bivalve shells (mainly Arctica islandica) of high frequency oceanographic and
climatic conditions during the last millennium. However, due to the absence of Arctica
islandica and similarly long-lived bivalves, sclerochronological palaeoenvironmental
studies of southern European coastal shelf seas are scarce. In particular, none of these
studies focus on reconstructing the variability of an eastern boundary upwelling
system.
The relatively long-lived bivalve (>100 years) Glycymeris glycymeris occurs in European
and North West African coastal shelf seas and provides a valid annually resolved archive of
environmental conditions during growth. Annual growth increment width series from living
G. glycymeris shells, collected in 2014 on the western Iberian continental shelf (ca. 35 m
water depth), were used to construct a statistically robust, ca. 70-year long absolutely-dated
chronology. Sub-annually resolved (11 to 22 samples per year) oxygen stable isotope
(δ18Oshell) data covering three years of shell growth, together with the direct evaluation
of the time of growth mark deposition in shells collected during the autumn and
winter months, were used to constrain the season of growth and to evaluate the
seasonal bias of the sea-surface temperature signal preserved in the δ18Oshelldata.
The growth increment width and δ18Oshell series, once robustly calibrated against
modelled and instrumental oceanographic and climatic series, potentially provide novel
insights into the variability of the western Iberia upwelling system and the associated
mechanisms.
This study was financed and conducted in the frame of the Portuguese Fundação para a
Ciência e Tecnologia (FCT) GLYCY Project (contract PTDC/AAC-CLI/118003/2010). |
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