A reconstruction of the depositional history and palaeoenvironment of the Plio-Pleistocene of northeast Iceland: A combined terrestrial and marine palynological approach
Verhoeven, K. (2012). A reconstruction of the depositional history and palaeoenvironment of the Plio-Pleistocene of northeast Iceland: A combined terrestrial and marine palynological approach. PhD Thesis. Ghent University, Department of Geology and Soil Science: Gent. 192 pp.
The research project of the dissertation was set up to investigate the combined response of terrestrial vegetation and marine algae to climate cooling effects. The geological period most suitable for the analysis of such a cooling is the transition from the Pliocene to the Quaternary, for it represents the greatest cooling event in recent history. Geologically speaking, the Pliocene epoch is not that far away in time, which as a result that most of the marine and terrestrial fauna and flora is near to the recent ones. Presentday ecological characteristics such as temperature sensitivity and nutrient dependency can therefore be used to reconstruct the Pliocene environment. In earlier geological epochs, the connection with recent fauna or flora decreases drastically and modern analogues are difficult to find. The Pliocene moreover knew much warmer environments than today and clear faunal and floral changes can be expected at the transition into the Quaternary. We selected the coastal geological outcrops of the Tjörnes Peninsula in northern Iceland for our study, as their northern location makes them very sensitive to the shifts of the climate zones. Also, their location central in the northern Atlantic should allow to detect possible changes in palaeoceanography. Therefore, the reconstruction of the sedimentary history of the Tjörnes sequence will help to decipher that of the global climate. The marine and terrestrial sediments of Tjörnes were studied for more than 200 years, but until now no coherent palynological study was made. Scientists knew the potential of the site, but the disadvantages of extreme low concentrations of palynomorphs and the difficulties to extract them from the sediments dissuaded intense research on the Tjörnes sequence. Thus, the study of the palynology was limited and mostly restricted to studies of the pollen and spores from the lignites, while a dinoflagellate study had not yet been carried out. The aim of our study was to combine both terrestrial and marine palynology of the marine sediments as well as the lignites. The extraction of the palynomorphs and the low concentrations of them hampered indeed the analysis, but in the end the analysis provided reasonable insight.All our research during the past six years focused on palynological studies with marine dinoflagellate cysts in combination with terrestrial pollen and spores from sediments deposited during the past five million years. Several studies of Pliocene and Pleistocene outcrops of the Tjörnes Peninsula, but also of the succession on Flatey Island, situated 2.5 km out of the coast in the same bay, were made, as they combine into a meaningful whole.
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