Sökning: "Radiocarbon dating"

Visar resultat 26 - 30 av 46 avhandlingar innehållade orden Radiocarbon dating.

1. 26. Diatom and Sedimentological Investigations on West Antarctic Shelf Sediment

   Författare :Charlotte Sjunneskog; Bjorg Stabell; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Antarctica; climate change; diatom abundance; geochemistry; Geovetenskap; Earth sciences; Geovetenskap; Quarternary Geology; kvartärgeologi;

   Sammanfattning : Climate and environmental change following the retreat of the last glacial ice sheet in the Antarctic Peninsula has been interpreted, employing diatom abundance, relative abundance of Chaetoceros resting spores and diatom assemblages as proxies. These together with sedimentological data and radiocarbon dating, suggest four major events that can be further subdivided. LÄS MER

3. 27. Environmental and climatic aspects of the early to mid Holocene calcareous tufa and land mollusc fauna in southern Sweden

   Författare :Björn Gedda; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; southern Sweden; environment; climate; Early Holocene; Calcareous tufa; mollusc; Skåne.; Geology; physical geography; Geologi; fysisk geografi;

   Sammanfattning : Although deposition of freshwater calcium carbonates, tufa, has occurred in large areas with carbonate soil or bedrock in Sweden, no tufa formation has been observed in Sweden. To better understand the factors controlling tufa formation in southern Sweden, bio- and lithostratigraphical studies were carried out on (paludal) calcareous tufa deposits in the province of Skåne. LÄS MER

4. 28. Tree-limit ecotonal response to Holocene climate change in the Scandes Mountains of west-central Sweden

   Författare :Jonas Bergman; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tree-limit ecotone; alpine vegetation; tephrochronology; peat humification; plant macrofossils; Palaeobotany; fylogeni; Paleobotanik; palynology; phylogeny; palynologi; Geologi; Geology; pedology; geomorphology; Physical geography; klimatologi; geomorfologi; climatology; Fysisk geografi; cartography; Holocene climate; palaeoecology; marklära; kartografi; pollen influx;

   Sammanfattning : The aim of this thesis was to reconstruct the Holocene vegetational and climatic development in the Sylarna-Storulvån area, western Jämtland, in the central Scandes Mountains. Temporal trends and fluctuations in the elevation and vegetational character of the tree-limit ecotone were studied mainly by means of pollen and plant macrofossil analysis of two lake sediment sequences (Lakes Stentjärn and Spåime), located above the present-day tree-limit. LÄS MER

5. 29. Late Quaternary Biostratigraphy of Sediments of the Southeastern Baltic Sea

   Författare :Daiva Üsaityté; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; SE Baltic Sea; pollen analysis; Late Quaternary; numerical zonation; principal components analysis; Geovetenskap; Earth sciences; Geovetenskap; Quarternary Geology; kvartärgeologi;

   Sammanfattning : This thesis presents Late Quaternary biostratigraphy in the SE Baltic Sea, based on palynological data from fifteen sediment cores. An objective subdivision of the cores has been achieved by numerical zonation. Ordination has revealed a succession of pollen spectra that can be used for biostratigraphic correlation across the region. LÄS MER

7. 30. Late Holocene humidity variability in central Sweden

   Författare :Sofia Andersson; Stefan Wastegård; Gunhild Rosqvist; Kristian Schoning; Frank Chambers; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; humidity change; stable isotopes; Chara spp; Pisidium spp; testate amoebae assemblages; humification; C N ratio; late Holocene; central Sweden; Quaternary geology; Kvartärgeologi; kvartärgeologi; Quarternary Geology;

   Sammanfattning : The aim of this thesis was to reconstruct humidity variability in central Sweden during the late Holocene. A multi-proxy approach was used to infer humidity changes as recorded in a lake and a mire. Age-models were constructed based on radiocarbon dating and the Askja-1875 tephra. LÄS MER