Palaeodirectional and palaeointensity results of Paleocene and Eocene basalts from West Greenland

• Main Authors: Janna Riisager, Peter Riisager, Mireille Perrin, M. Palaeodirectional
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: tensity; Thellier method; Tertiary; Curie Point; Greenland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.575.7257; http://2dgf.dk/xpdf/bull46-1-69-78.pdf

aeointensity results of Paleocene and Eocene basalts from West Greenland. Bul-letin of the Geological Society of Denmark, Vol. 46, pp. 69–78. Copenhagen. Twelve sites (57 drill cores) from two lava series and one dike were sampled for a palaeomagnetic study of the late Paleocene and early Eocene West Greenland flood basalts. Most of the rocks exhibited well-defined one component remanent magnetization with high unblocking temperatures (mostly above 500°C) and high median destructive fields (30–40 mT). All the rocks are reversely magnetized and, when combined with 40Ar/39Ar ages (Storey et al. 1998), a direct correlation with the geomagnetic polarity time scale can be made. Rock magnetic experiments indicate varying degree of both high temperature (deuteric) and low temperature (hydrothermal) oxidation of primary titanomag-netite. Twenty-three samples with high Curie point (~570°C) were chosen for Thellier palaeointensity experiments. Eleven of them, coming from three differ-ent cooling units, yielded reliable palaeointensity estimates. The results are rea-sonably coherent within sites, and the site-mean virtual dipole moments (VDM) are 1.8, 9.0 and 15.4×1022 Am2. The lowest VDM most probably corresponds to the ~94 ka long C24n.1r subchron, while the two other VDM’s close to present-day and higher than present-day values correspond to chrons C26r and C24r respectively.