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| Titel |
Deglacial-Holocene variability of sea ice and surface water temperature in the Bering Sea: Reconstruction based on "IP25" and alkenone data |
| VerfasserIn |
M. Meheust, R. Stein, K. Fahl |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061297
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| Zusammenfassung |
| Overall goal of our study of sediment material collected during RV Sonne Cruise 202 (INOPEX) in 2009 (Gersonde et al., Curise Report 2009), is the reconstruction of the short-term variability of sea-ice, sea-surface temperature (SST), primary productivity and terrigenous input in the subpolar North Pacific/Bering Sea and their relationship to global climate change, using organic-geochemical proxies (i.e. organic-geochemical bulk parameters and biomarkers such as: TOC, hydrogen indices; long-chain n-alkanes, sterols, alkenones; Uk37 and TEX86-Index; BIT-Index; HBIs, IP25, PIP25). In a first phase, these organic-geochemical proxies have been determined in surface sediments. The results show that the biomarker proxies reflect modern sea-ice and SST distributions as well as areas of increased primary productivity and increased input of terrigenous (organic) matter quite well. In a second phase of the project, the biomarkers have been determined in three selected sediment cores:
Core SO 202-18-6 (Umnak Plateau/Bering Sea; 60.127°N, 179.444°W; water depth 1105 m; core length 7.21 m; age interval 0 to 14 kyr.BP).
Core SO 202-07-6 (Detroit Seamount/western subpolar North Pacific; 51.272°N, 167.700°W; water depth 2340 m WD; core length 4.69 m; age interval MIS 1 to 3).
Core SO 202-27-6 (Patton Seamount/eastern subpolar North Pacific; 54.296°N, 149.600°W; water depth 2919 m; core length 2.91 m: age interval MIS 1 to 3).
Here, we concentrate especially on the variability of sea-ice cover and SST, using the newly developed sea-ice proxy "IP25" (Belt et al., 2007) and alkenone data, respectively, determined in the AMS14C-dated Core SO 202-18-6. Based on these biomarker records, sea-ice cover and SST changed significantly in the northern Bering Sea during Deglacial-Holocene times. The Younger Dryas interval is characterized by extended sea-ice cover, coinciding with a drop in SST to 2-4°C. With the end of the Younger Dryas, between 460 and 420 cmbsf, sea-ice cover decreased with increasing SST. Between 420 and 120 cmbsf representing the early Holocene (Thermal Maximum), IP25 is absent and maximum SST of about 6°C was reached. During the upper 120 cmbsf representing the late Holocene, IP25 occurred again and increased towards the top, paralleled by a decrease in SST of about 3°C. A very similar contemporaneous trend of increasing sea-ice cover during the late Holocene was recorded in the northernmost North Atlantic (Fram Strait), paralleled by an advance of glaciers in Norway, a colder climate over Greenland, a colder and dryer climate in Siberia, and a decrease in Siberian river discharge (Stein et al., 2004; Müller et al., 2009; 2012).
References
Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Org. Geochem. 38, 16-27.
Müller, J., Massé, G., Stein, R., and Belt, S., 2009. Extreme variations in sea ice cover for Fram Strait during the past 30 ka. Nature Geoscience, DOI: 10.1038/NGEO665.
Müller, J., Werner, K., Stein, R., Fahl, K., Moros, M., and Jansen, E., 2012. Holocene cooling culminates in sea ice oscillations in Fram Strait. Quat. Sci. Rev., under revision.
Stein, R., Dittmers, K. , Fahl, K. , Kraus, M. , Matthiessen, J. , Niessen, F. , Pirrung, M., Polyakova, Ye., Schoster, F. , Steinke, T. , and Fütterer, D.K., 2004. Arctic (Palaeo) River Discharge and Environmental Change: Evidence from Holocene Kara Sea Sedimentary Records. Quaternary Science Reviews 23: 1485-1511. |
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