Sökning: "palaeomagnetism"

Visar resultat 1 - 5 av 10 avhandlingar innehållade ordet palaeomagnetism.

1. 1. Geography and geometry of pre-Caledonian western Baltica: U-Pb geochronology and Palaeomagnetism

   Författare :Emma Rehnström; Berggrundsgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical geography; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi; Fennoscandia; correlations; Baltica; Early Palaeozoikum; palaeogeography; orthogneisses; nappes; palaeomagnetism; U-Pb geochronology; Caledonian orogen; Scandinavia;

   Sammanfattning : In an attempt to reconstruct the pre-Caledonian cratonic margin of Fennoscandia, U-Pb geochronological and geochemical investigations have been performed on allochthonous orthogneisses in the northern Swedish Caledonides. The crystalline basement of the nappes have also been examined to further constrain the continuation of various chronologically defined orogenic belts. LÄS MER

3. 2. Improving archaeomagnetic dating through new data acquisition and method development

   Författare :Megan Allington; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Archaeomagnetism; Palaeomagnetism; Geomagnetic field; Archaeomagnetic dating;

   Sammanfattning : The Earth’s magnetic field (or geomagnetic field) has been measured for hundreds of years, starting with maritime observations from logbooks for navigation purposes to present day real-time recording by satellites. From these records, the geomagnetic field variation throughout recent time is well-understood. LÄS MER

4. 3. Crystal chemistry of Fe-Ti oxides in mafic rocks and metabasites: A study aimed at refinement of geological tools and interpretations

   Författare :Benyam Estifanos; Berggrundsgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fe-Ti oxide; hercynite; siderite; stilpnomelane; olivine corona; Swedish Caledonides; hysteresis; PIXE; synchrotron XRD; Rietveld; microprobe; red corundum; palaeomagnetism; eclogite; plagioclase clouding; dolerite; pyroxene gneiss; Geology; physical geography; Geologi; fysisk geografi;

   Sammanfattning : This thesis consists of four subprojects: (A) ‘Clouding of plagioclase by Fe-Ti oxides’, (B) ‘Fe-Ti oxides during high-pressure metamorphism of mafic rocks’, (C) ‘Magnetic study of Fe-Ti oxides in mafic rocks and metabasites’, and (D) ‘Topotactic phase transitions in oxide minerals’. A) In southern Sweden dolerite dikes and gabbros with clouded plagioclase are common. LÄS MER

5. 4. Investigations of temporal changes in climate and the geomagnetic field via high-resolution radiocarbon dating

   Författare :Anette Mellström; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; wiggle-matching; Radiocarbon dating; 14C; 2800 cal BP; climate change; solar activity; palaeomagnetism; lake sediments; varves; post-depositional remanent magnetisation; PDRM; lock-in; peat deposits; Sweden;

   Sammanfattning : Geological archives have shown periods of abrupt climate change in the relatively stable Holocene epoch (last ca. 11 700 years). One of these periods was around 2800 cal BP. Several records, mainly from Europe, reveal a shift towards wetter, cooler and windier conditions. LÄS MER

7. 5. 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