A reconstruction of the depositional history and palaeoenvironment of the Plio-Pleistocene of northeast Iceland: a combined terrestrial and marine palynological approach
Our dissertation focusses on the coastal area of Tjörnes in northern Iceland, as this location harbours a key section for the understanding of the climate shifts of our hemisphere. However up to now, little was known about the concentrations, preservation and possible disturbances by reworking of pa...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Ghent University. Faculty of Sciences
2012
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| Online Access: | https://biblio.ugent.be/publication/3137680 http://hdl.handle.net/1854/LU-3137680 https://biblio.ugent.be/publication/3137680/file/4336330 |
| Summary: | Our dissertation focusses on the coastal area of Tjörnes in northern Iceland, as this location harbours a key section for the understanding of the climate shifts of our hemisphere. However up to now, little was known about the concentrations, preservation and possible disturbances by reworking of palynomorphs in the deposits. Also, a solid age model for the Tjörnes section was not available, as the dominantly marine sediments yielded only weak palaeomagnetic signals and no absolute dating could be applied to them (Eiríksson et al., 1990; Kristjánsson, 2004). The magnetic polarities and K/Ar ages of the lava layers (Aronson and Sæmundson, 1975; Albertsson, 1976, 1978) in sequence formed the fragile framework of the age model, and the low potassium content of the radiometric sample also introduced much uncertainty. Moreover the sedimentary rocks could only be positioned indirectly in the timeframe and hiatuses between lava and sediment layers could not be demonstrated. In our study, we analyzed the terrestrial and marine palynomorphs of the Tjörnes beds, of four interglacials of the Breidavík Group and of two levels of the Flatey succession on the homonymous island near the Tjörnes coastal area. Lignites as well as marine sediments were included in the analysis. The preparation and study of the palynomorphs did not present particular problems. However, in the Tjörnes section, the concentrations of the dinoflagellate cysts is rather low, but the preservation is good and only a limited influx of reworked palynomorphs is observed (chapter 2). Although the concentrations were low, the number of species was quite large. Because of the coastal position of the sedimentation basin, a diverse heterotrophic flora could develop, yielding much ecological data (chapter 3). A new dinoflagellate cyst named Selenopemphix islandensis was found and appears to be useful as a biostratigraphical marker (chapter 4). A large variety of pollen from plants, today generally extinct in Iceland, occurs in the Tjörnes section (chapter 1). A ... |
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