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| Titel |
Comparison of four independent paleotemperature records over the last 800 ka in the South-West Indian Ocean: similarities and differences |
| VerfasserIn |
Thibaut Caley, Jung-Hyun Kim, Bruno Malaizé, Jacques Giraudeau, Thomas Laepple, Nicolas Caillon, Karine Charlier, Hélène REBAUBIER, Linda Rossignol, Isla Castañeda |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045966
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| Zusammenfassung |
| Well-dated paleotemperature records are essential for detecting natural climate variations beyond the instrumental period and to validate climate models that provide past climate scenarios and climate forecasts. Paleoclimate records are often derived from proxies based on sedimentary inorganic and organic matter. Proxies based on inorganic remnants include those based on foraminiferal assemblages (Imbrie and Kipp, 1971), isotopic (Shackelton and Opdyke, 1973) and trace element composition (Anand et al., 2003) of carbonate shell. Organic proxies include the alkenone unsaturation index (e.g. Brassell et al., 1986) based on long-chain unsaturated alkenones synthesized by haptophyte algae and TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) based on glycerol dialkyl glycerol tetraethers (GDGTs) derived from the membrane lipids of Marine group I Crenarchaeota (Schouten et al., 2002). More recently, TEX86 has been modified with a logarithmic function, called TEX86H (Kim et al., 2010). The availability of multiple proxies allows the reconstruction of more than one temperature record from a single sediment core. We will present four independent temperature records (Mg/Ca on G. ruber planktonic foraminifera,TEX86H ,alkenone, and foraminifera transfer function using the Modern Analogue Technique) covering the last 800 ka from a sediment core located directly beneath the present corridor of the Agulhas Current (MD96-2048, 26°10’482S, 34°01’148E, 660 m). We observe both similarities and differences among four records in terms of changes in variation and amplitude. The possible biasing factors for each proxy such as seasonality, salinity effect, production depth, and lateral transport will be discussed in detail.
References:
Anand, P., Elderfield, H., and Conte, M.H., 2003. Calibration of Mg/Ca thermometry in planktonic foraminifera from a sediment trap time series. Paleoceanography 18, n°.2, 1050.
Brassell, S.C., Eglinton, G., Marlowe, I.T., Pflaumann, U., and Sarnthein, M., 1986. Molecular stratigraphy: a new tool for climatic assessment. Nature 320, 129-133.
Imbrie, J., Kipp, N., 1971. A new micropaleotological method for quantitative paleoclimatology: Apllication to a late Pleistocene Caribbean core. In: K. K. Turekian (Ed.), The late Cenozoic glacial ages (pp. 71-181). New Haven, Connecticut: Yale University Press.
Kim, J.-H. et al., 2010. New indices and calibrations derived from the distribution of crenarchaeal isoprenoid tetraether lipids: Implications for past sea surface temperature reconstructions. Geochim. Cosmochim. Acta, doi:10.1016/j.gca.2010.05.027.
Schouten, S., Hopmans, E.C., Schefuß, E., and Sinninghe Damsté, J.S., 2002. Distributional variations in marine crenarchaeotal membrane lipids: A new organic proxy for reconstructing ancient sea water temperatures? Earth and Planetary Science Letters 204, 265-274.
Shackleton, N.J., & Opdyke, N.D., 1973. Oxygen isotope and palaeomagnetic stratigraphy of equatorial Pacific core V28-238 : Oxygen isotope temperatures and ice volumes on a 100 kyrs and 1000 kyrs scale, J. Quaternary research, 3(1), 39-54. |
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