Search for dissertations about: "Proterozoic"
Showing result 1 - 5 of 36 swedish dissertations containing the word Proterozoic.
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1. Geochemistry of tin, tungsten and molybdenum in Swedish Proterozoic granitoids : its potential use in regional mineral exploration
Abstract : The primary aim of this broad regional study is to statistically determine the Li-Sn-W-Mo-bearing potential of various granitoids using geochemical criteria.Computer-based, univariate and multivariate statistical methods are applied to major and trace element data from ca 660 granitic rock samples and over 800 major element analyses, selected from the Swedish geological literature. READ MORE
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2. Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems
Abstract : To understand the growth of continental crust, the balance between juvenile mantle derived extraction, infracrustal reworking and crustal recycling, needs to be estimated. Since the beginning of the century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address these questions have increased exponentially. READ MORE
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3. Phosphate and Arsenic Cycling under Experimental Early Proterozoic Marine Conditions
Abstract : Nutrient dynamics in the Archean-Paleoproterozoic oceans strongly influenced primary productivity and the rise of atmospheric O2. Reconstructing the cycling of key nutrients such as dissolved inorganic phosphate (DIP) at this time is important for our understanding of the timing, rate and extent of atmospheric oxygenation at this time. READ MORE
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4. Microfossils of eukaryotic cysts through time : A study of Precambrian-Ordovician organic-walled microbiota
Abstract : .... READ MORE
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5. 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
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