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| Titel |
Reconciling single-chamber Mg / Ca with whole-shell δ18O in surface to deep-dwelling planktonic foraminifera from the Mozambique Channel |
| VerfasserIn |
J. Steinhardt, C. Cleroux, L. J. de Nooijer, G.-J. Brummer, R. Zahn, G. Ganssen, G.-J. Reichart |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 8 ; Nr. 12, no. 8 (2015-04-24), S.2411-2429 |
| Datensatznummer |
250117910
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| Publikation (Nr.) |
 copernicus.org/bg-12-2411-2015.pdf |
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| Zusammenfassung |
| Most planktonic foraminifera migrate vertically through the water column
during life, meeting a range of depth-related conditions as they grow and
calcify. For reconstructing past ocean conditions from geochemical signals
recorded in their shells, it is therefore necessary to know vertical habitat
preferences. Species with a shallow habitat and limited vertical migration
will reflect conditions of the surface mixed layer and short-term and mesoscale
(i.e. seasonal) perturbations therein. Species spanning a wider range of
depth habitats, however, will contain a more heterogeneous, intra-specimen
variability (e.g. Mg / Ca and δ18O), which is less for species
calcifying below the thermocline. Obtained single-chamber Mg / Ca ratios are combined
with single-specimen δ18O and δ13C of the surface-water inhabitant Globigerinoides ruber, the thermocline-dwelling Neogloboquadrina dutertrei
and Pulleniatina obliquiloculata, and the deep dweller Globorotalia scitula from
the Mozambique Channel. Species-specific Mg / Ca, δ13C and
δ18O data combined with a depth-resolved mass balance model
confirm distinctive migration and calcification patterns for each species as
a function of hydrography. Whereas single-specimen δ18O rarely
reflects changes in depth habitat related to hydrography (e.g. temperature),
measured Mg / Ca of the last chambers can only be explained by active
migration in response to changes in temperature stratification.
Foraminiferal geochemistry and modelled depth habitats shows that the single-chamber Mg / Ca and single shell δ18O are in agreement with each
other and in line with the changes in hydrography induced by eddies. |
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