Sökning: "late Holocene"

Visar resultat 1 - 5 av 58 avhandlingar innehållade orden late Holocene.

1. 1. 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

3. 2. Paleoclimate and seasonality on Sumatra during the Late Glacial and Holocene : Insights from biomarkers and climate model simulations

   Författare :Lars Petter Hällberg; Malin Kylander; Frederik Schenk; Rienk Smittenberg; David Naafs; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Holocene; Late Glacial; biomarkers; organic geochemistry; climate model; hydrogen isotopes; stable isotopes; paleoclimate; alkanes; GDGT; brGDGT; H-GDGT; bacterial community shifts; paleothermometry; precipitation reconstruction; peat; geokemi; Geochemistry;

   Sammanfattning : Deep atmospheric convection in the Indo-Pacific Warm Pool (IPWP) is a key driver of the Hadley and Walker Circulations that modulate the Asian-Australian monsoons and the El Niño Southern Oscillation (ENSO). Temperature and rainfall seasonality, i.e. LÄS MER

4. 3. Assessing Holocene and late Pleistocene geomagnetic dipole field variability

   Författare :Andreas Nilsson; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geomagnetic field; palaeomagnetism; the Holocene; dipole tilt; dipole moment; cosmogenic radionuclides;

   Sammanfattning : Palaeomagnetic studies of continuous geological archives and archaeological artefacts are required to reconstruct geomagnetic field changes beyond the range of historical observations. In this thesis I assess the reliability of sedimentary palaeomagnetic data and Holocene dipole field reconstructions. LÄS MER

5. 4. Late Weichselian and early Holocene changes of vegetation, climate and sea level on the Skagi peninsula, northern Iceland

   Författare :Mats Rundgren; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; asthenosphere viscosity; glacial loading unloading; marine polar front migrations; sea-level change; climate change; vegetation change; Early Holocene; Late Weichselian; Iceland; Lake sediments; Skagi peninsula; Geology; physical geography; Geologi; fysisk geografi;

   Sammanfattning : Sediment sequences from five lakes on the Skagi peninsula, northern Iceland, were subjected to mineral magnetic analysis, carbon analysis, pollen analysis, plant macrofossil analysis, diatom analysis, radiocarbon dating and tephra analysis in order to make detailed reconstructions of vegetation, climate and sea level during the Late Weichselian and Early Holocene. The main purpose was to investigate if the dramatic deglacial climatic shifts recorded in proxy records from the North Atlantic region, such as ice cores, marine sediments and lake sediments, also are registered in Skagi lake sediments, which would be expected considering Iceland´s position in the middle of the North Atlantic Ocean, within the range of the Late Weichselian–Early Holocene migrations of the marine polar front. LÄS MER

7. 5. The Late Holocene history of beech Fagus sylvatica and Norway spruce Picea abies at stand-scale in southern Sweden

   Författare :Leif Björkman; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; physical geography; Geology; south Sweden; Late Holocene; succession; disturbance; forest history; forest continuity; population dynamics; immigration; palaeoecology; pollen analysis; Fagus sylvatica; Picea abies; Geologi; fysisk geografi; Palaeobotany; phylogeny; palynology; Paleobotanik; fylogeni; palynologi;

   Sammanfattning : High resolution pollen analysis was carried out on five peat profiles from small forest hollows at four sites in southern Sweden. The general aim was to investigate the establishment of Fagus sylvatica and Picea abies at stand-scale. LÄS MER