Search for dissertations about: "geochronology"

Showing result 6 - 10 of 53 swedish dissertations containing the word geochronology.

2. 6. The tectonic evolution of the western part of the Svecofennian orogen, central Sweden : Insight from U/Pb and 40Ar/39Ar geochronology at Forsmark

   Author : Tobias Hermansson; Berggrundsgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; physical geography; Geology; Svecofennian orogen; Tectonic models; Tectonic cycles; Uplift; Cooling; Ductile deformation; Geochronology; U Pb; 40Ar 39Ar; Geologi; fysisk geografi; Petrology; mineralogy; geochemistry; Petrologi; mineralogi; geokemi;

   Abstract : The Forsmark area, in the western part of the Svecofennian orogen, central Sweden, is situated between two major Palaeoproterozoic tectonic domains that show contrasting histories with respect to timing of igneous activity, ductile deformation and metamorphism. At Forsmark, WNW to NW trending, ductile deformation belts anastomose around tectonic lenses with an inferred lower degree of ductile strain. READ MORE

4. 7. Mesoproterozoic crustal evolution in Southern Africa

   Author : Åsa Pettersson; Göteborgs universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Namaqua-Natal province; Mezoproterozoic; geochronology; U-Pb zirkon dating; Sm-Nd model ages; Ar-Ar dating; Southern Africa;

   Abstract : The objects of this thesis were to use geochronology to investigate crustal evolution of part of Southern Africa that formed during a global event, resulting in the ~1 Ga supercontinent Rodinia. The timing of assembly by continent-continent collisions and the position of the individual continental blocks of this ancient landmass is still largely unknown. READ MORE

5. 8. Utilizing a tectonic framework to constrain the mineral system and remobilization in the Kiruna mining district, Sweden

   Author : Leslie Logan; Tobias E. Bauer; Fernando Tornos; Olof Martinsson; Paul Evins; Luleå tekniska universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Kiruna; tectonic framework; mineral system; IOCG; IOA; remobilization; sulfur isotopes; trace elements; geochronology; Pahtohavare; Viscaria; Rakkurijärvi; Malmgeologi; Ore Geology;

   Abstract : The Kiruna mining district, located in the northern Norrbotten ore province, Sweden, is a geologically and economically important area, being the type-locality for Kiruna iron oxide-apatite (IOA) deposits and also host to a variety of other deposits including syngenetic stratiform exhalative Cu-(Fe-Zn) (Viscaria, Eastern Pahtohavare), epigenetic stratabound Cu ± Au (Pahtohavare), and iron oxide-copper-gold (IOCG, Rakkurijärvi) deposits. However, the timing of IOA versus IOCG within the tectonic evolution is in question based on structural investigations showing Cu- and Fe-sulfides occur in late-orogenic structures. READ MORE

6. 9. Geological Evolution of the Supracrustal Palaeoproterozoic Hamrånge Group: A Svecofennian Case Study

   Author : Erik Ogenhall; Håkan Sjöström; Hans Annersten; Markku Väisänen; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Hamrånge; Ljusdal; Hagsta Gneiss Zone; geochemistry; geochronology; thermobarometry; metamorphism; fold-thrust belt.; Earth sciences; Geovetenskap; Geovetenskap med inriktning mot mineralogi; petrologi och tektonik; Earth Science with specialization in Mineral Chemistry; Petrology and Tectonics;

   Abstract : The work presented in this thesis utilizes several geological methods to investigate the origin and evolution of the supracrustal rocks in the Palaeoproterozoic Hamrånge Group (HG) in the south-central Swedish Svecofennian. The first paper is based on whole-rock geochemistry to show the plate tectonic setting of volcanic rocks within the HG. READ MORE

7. 10. Testing palaeomagnetic and 14C based geochronological methods in the Baltic Sea

   Author : Bryan Lougheed; Kvartärgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Baltic Sea; coastal; geochronology; palaeomagnetic secular variation; PSV; radiocarbon; 14C; reservoir age; R t ; ΔR; salinity; δ18O; geomagnetic field; Holocene; deglacial; Fennoscandia.;

   Abstract : The Baltic Sea is a continental shelf sea that is influenced by both river runoff and marine water. The two water masses are vertically stratified in the Baltic Sea, resulting in a positive, estuarine circulation system, which has undergone changes in the past due to isostatic uplift of the Baltic basin. READ MORE