Search for dissertations about: "Archean"

Showing result 1 - 5 of 11 swedish dissertations containing the word Archean.

2. 1. U-Pb dating of detrital zircon from the Mt. Alfred area, Yilgarn Craton, Western Australia

   Author : Ross Kielman; Martin Whitehouse; Alexander Nemchin; Victoria Pease; Åke Johansson; Jenny Andersson; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Detrital zircon; Geochronology; Archean; Hadean; Western Australia; Geology; geologi;

   Abstract : Hadean and Paleo-Eoarchean aged detrital zircon provide a rare glimpse into the nature of the early Earth. Thus, the characterisation of new localities with rocks that host Hadean and Paleo-Eoarchean zircon provide invaluable insight into the Earth’s early crust. READ MORE

4. 2. U-Pb baddeleyite geochronology of Precambrian mafic dyke swarms and complexes in southern Africa - regional scale extensional events and the origin of the Bushveld Complex

   Author : Johan Olsson; Berggrundsgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; U-Pb TIMS geochronology; geochemistry; baddeleyite; mafic dyke swarms; mantle plume; Bushveld Complex; Kaapvaal Craton; Zimbabwe Craton; Archean; Proterozoic;

   Abstract : Dolerite dykes are formed when iron- and magnesium-rich (mafic) mantle-derived magmas ascend through the lithosphere (upper part of the mantle) and crystallize as ‘hydro-fractures’ within the crust. Dykes may exist in great numbers to form dyke swarms (linear or radiating), which can be linked to time periods of continental break-up, or attempted break-up events, associated with voluminous volcanism. READ MORE

5. 3. Timing and Origin of Igneous Rocks in the Gällivare area, Northern Sweden

   Author : Zimer Sarlus; Christina Wanhainen; Sabina Strmic Palinkas; Luleå tekniska universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ore Geology; Malmgeologi;

   Abstract : The Gällivare area is one of Europe’s top mining regions. The area is located in the northern Norrbotten ore district which hosts ore deposits such as the Malmberget underground iron ore mine, the Aitik open pit Cu-Au mine and the currently explored Nautanen Cu-Au deposit. In addition, several small, mineralized bodies are found. READ MORE

6. 4. Cambro-Ordovician microorganisms: acritarchs and endoliths

   Author : Martin Stockfors; Malgorzata Vidal-Moczydlowska; John S. Peel; Kenneth John Dorning; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Cambrian; Ordovician; acritarch; endolith; Kolguev Island; North Greenland; Stratigraphy; Geovetenskap; Earth sciences; Geovetenskap;

   Abstract : Organic-walled microfossils are abundant and taxonomically diverse in Cambrian-Ordovician strata; some are important for biostratigraphy and for the correlation of geological successions. New assemblages of Cambrian-Ordovician acritarchs from Kolguev Island, Arctic Russia and Middle Cambrian ichnofossils of endoliths from Peary Land, North Greenland are studied. READ MORE

7. 5. Isotropic and Anisotropic P and S Velocities of the Baltic Shield Mantle : Results from Analyses of Teleseismic Body Waves

   Author : Tuna Eken; Roland Roberts; Uli Achauer; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; teleseismic tomography; mantle lithosphere; seismic anisotropy; teleseismic earthquakes; shear wave splitting; Earth sciences; Geovetenskap; Geophysics Specialized In Seismology; geofysik; med inriktning mot seismologi;

   Abstract : The upper mantle structure of Swedish part of Baltic Shield with its isotropic and anisotropic seismic velocity characteristics is investigated using telesesismic body waves (i.e. P waves and shear waves) recorded by the Swedish National Seismological Network (SNSN). READ MORE