Geological setting

• Main Author: Agnete Steenfelt
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland; East Greenland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.624.6482; http://www.minersoc.org/pages/Archive-MM/Volume_46/46-339-201.pdf

ABSTRACT. The Caledonian fold belt of East Greenland contains calc-alkaline granite (sensu lato) intrusions with ages ranging from c.2000 Ma to c.350 Ma. The Protero-zoic granites have low U contents and the pre-Devonian Caledonian granites contents of U corresponding to the clarke value for U in granites. Some aspects of the geochemistry of U are discussed using U-K/Rb, U-Sr, U-Zr, and U-Th diagrams. Secondary enrichment and mineralization ccurs in fractured and hydrothermally altered granites and rhyolites ituated in or near a major NNE fault zone. The U is associated with iron oxides or hydrocarbons. It is suggested that the source of the mineralization was Devonian acid magma, which also acted as a heat source for circulating hydrothermal fluids. T HE content and distribution ofU in granites from the Caledonides of Scotland, Ireland, and the eastern United States of America have recently been studied in relation to the geochemistry and tectonic setting of the granites, and to the occur-rence of U mineralization (e.g. Simpson et al., 1979; Rogers et al., 1978). This paper presents the results of preliminary studies of granites of the East Greenland Caledonian fold belt, which can be viewed as a northwards continuation f the British