Arctic Ocean warmings from the last glaciation to the present : implementing and assessing the reliability of planktic foraminiferal paleoreconstructions

• Main Author: Zamelczyk, Katarzyna Agnieszka
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universitetet i Tromsø 2012
• Subjects: VDP::Mathematics and natural science: 400::Geosciences: 450::Marine geology: 466; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Marin geologi: 466; VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452; VDP::Mathematics and natural science: 400::Geosciences: 450::Stratigraphy and paleontology: 461; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Stratigrafi og paleontologi: 461; VDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456; DOKTOR-004; Arctic; Arctic Ocean; Rasmussen; Aagaard; Climate change; Foraminifera*; Fram Strait; Sea ice
• Online Access: https://hdl.handle.net/10037/4148

The papers of this thesis are not available in Munin: 1. Zamelczyk, K., Rasmussen, T.L, Husum, K., Haflidason, H., de Vernal, A., Ravna, E.K., Hald, M. and Hillaire-Marcel, C.: 'Between two oceanic fronts : Paleoceanographic changes and calcium carbonate dissolution in the central Fram Strait during the last 20,000 years' (manuscript in revision for Quaternary Research). 2. Zamelczyk, K., Rasmussen, T.L., Husum, K. and Hald, M.: 'Marine calcium carbonate preservation vs. climate change over the last two millennia in the Fram Strait : implications for planktic foraminiferal paleostudies' (manuscript submitted to Marine Micropaleontology). 3. Zamelczyk, K., Husum, K., Rasmussen, T.L., Godtliebsen, F. and Hald, H.: 'Surface water conditions and calcium carbonate preservation in the Fram Strait during the late Weichselian 29,000-16,000 years BP', (manuscript to be submitted to Paleooceangraphy). 4. Spielhagen, R. F.,Werner, K., Aagaard-Sørensen, S., Zamelczyk, K., Kandiano,E., Budeus, G., Husum, K., Marchitto, T., and Hald, M.: 'Enhanced modern heat transfer to the Arctic by warm Atlantic Water', Science (2011), vol. 331 no. 6016:450-453. Available at http://dx.doi.org/10.1126/science.1197397 5. Werner, K., Spielhagen, R.F., Bauch, D., Hass, H.Ch., Kandiano, E. and Zamelczyk, K.: 'Atlantic Water advection to the eastern Fram Strait- Multiproxy evidence for late Holocene variability', Palaeogeography, Palaeoclimatology, Palaeoecology (2011), vol. 308 no. 3-4:264-276. Available at http://dx.doi.org/10.1016/j.palaeo.2011.05.030 The aim of the PhD study was to use planktic foraminifera to elucidate paleoceanographic variability and the preservation state of calcium carbonate in the eastern Fram Strait throughout the last 30,000 years. Sediment cores were studied using a multiproxy approach which included analyzing planktic and benthic foraminiferal fauna distribution patterns, measurements of stable isotopes (δ18O, δ13C), grain size analysis, IRD counts, and chemical analysis of bulk sediment. In addition, mean shell weight records combined with fragmentation indices were applied. Three time periods representing important oceanographic changes in the Fram Strait were investigated with a high temporal resolution. The results show that the Atlantic water inflow governed the oceanographic development and had an important influence on the preservation state of calcium carbonate in the Fram Strait. The best preserved planktic foraminifera assemblages during the last 30,000 years were found during the Last Glaciation Maximum. Some minor dissolution events occurred during the Last Glacial Maximum as response to seasonally changing physical oceanographic parameters, sea ice formation, increased surface productivity, and melt water pulses. During the deglaciation and the Holocene, the preservation state of carbonates generally deteriorated. This trend was interrupted at 10,800-8000 BP, where the preservation of planktic foraminifera markedly improved. Changes in preservation are related to the extent and influence of the Arctic water and the marginal ice zone (MIZ) and its associated high organic productivity in the surface waters. During the last century, the preservation of small subpolar species improved. This coincided with distinctly increased sedimentation rates in the eastern and central Fram Strait. This study of planktic foraminifera preservation has shown that carbonate dissolution is a common phenomenon in the Fram Strait and should be considered in paleoreconstructions based on planktic foraminifera fauna.