Sökning: "Kjell Billström"

Hittade 3 avhandlingar innehållade orden Kjell Billström.

1. 1. Isotopic studies of two early Proterozoic sulphide ores in the Bergslagen district, south-central Sweden

   Författare :Kjell Billström; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Two sulphide ores in Beraslaqen (Svärdsio and Ammeberq), south-central Sweden, have been examined for their isotope characteristics in order to elucidate their qenetic oriqin. The obtained isotopic data point to a common volcanic-exhalative mode of formation in aqreement with recent qeochemical data. LÄS MER

3. 2. Abundance and fractionation of rare earth elements in calcite and other secondary minerals in fractures in the upper kilometre of crystalline bedrock, SE Sweden

   Författare :Olga M. Maskenskaya; Mats Åström; Kjell Billström; Linnéuniversitetet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; secondary minerals; rare earth elements; isotopes; crystalline bedrock;

   Sammanfattning : This thesis focuses on the geochemistry of secondary minerals, mainly calcite but also others such as fluorite and Ca/Al silicates, precipitated throughout the last 1.5 billion years in fractures of crystalline rock, SE Sweden. LÄS MER

4. 3. New Zircon geochronological and Nd isotopic evidence for Neoproterozoic crust reworking events in the Abas terrane, Yemen

   Författare :Fitsum Girum Yeshanew; Victoria Pease; Martin Whitehouse; Hugh Rollinson; Kjell Billström; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Precambrian; Arabian Shield; magmatism; U-Pb; zircon; post-collisional magmatism; Nd isotopes; Geology; geologi;

   Sammanfattning : The Arabian-Nubian Shield is an excellent natural laboratory to study crust formation processes during the Neoproterozoic. It is one of the largest juvenile tracts of continental crust formed during this time. It diachronously evolved between the breakup of Rodinia (c.780 Ma) and amalgamation of Gondwana (c. LÄS MER