Climatic variability during MIS 7 in the Norwegian Sea; based on benthic and planktonic foraminiferal fauna and stable oxygen isotopes
Abstract
A new record (MD99-2288) from the Vøring Plateau in the Norwegian Sea has been investigated with emphasis on surface and intermediate water masses during stage MIS 7. The core was raised from a water depth of 1262 m situated under the influence of the Norwegian Sea Arctic Intermediate Water (NSAIW) (and the Norwegian Sea Deep Water (NSDW). A total of ca. 140 samples are analysed with regard to foraminiferal assemblages (benthic and planktonic), stable oxygen/carbon isotopes (Neoglobigerina pachyderme s., Cassidulina neoteretis), grain size distribution and MSCL-analyses. The age model of MIS 7 is based on the stable oxygen isotopes of benthic and planktonic foraminifera and the oxygen isotope curves are compared with recent records from the North Atlantic The MIS 7 record in the Norwegian Sea is found to be in general accordance with other records further south. The stage is however characterised by one very cold stadial, MIS 7.4, with high d18O values. Towards the end of the stadial the oxygen isotopes are characterised by some very low d18O values, which imply sever conditions during that event. This event falls together with faintly laminated sediments deposited at a sedimentation rate of approximately 11 cm per ka. Further, MIS 7.3 is found to be warmer than MIS 7.5. Both interstadials show low d18O values and a high percentage of Bulimina and Cibicides species. This suggests a stronger influence of warm water masses. Compared to records further south MIS 7.2 and 7.1 show higher d18O values earlier in time and the d18O values are nearly comparable to the values during MIS 6. The sedimentation rate (terrigenous input) is also increasing during this time period (ca. 7.5 cm per ka) compared to MIS 7.3 (2.2 cm per ka). The significant increase in the percentage of Cassidulina neoteretis (ca. 80 percent) suggests that shift to cooler climate.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFMPP41C0687G
- Keywords:
-
- 1521 Paleointensity;
- 1635 Oceans (1616;
- 3305;
- 4215;
- 4513);
- 3305 Climate change and variability (1616;
- 1635;
- 3309;
- 4215;
- 4513);
- 3309 Climatology (1616;
- 1620;
- 3305;
- 4215;
- 8408);
- 4215 Climate and interannual variability (1616;
- 1635;
- 3305;
- 3309;
- 4513)