High Resolution Record of the C27n-C26r Geomagnetic Transition in West Greenland Flood Basalts

In central West Greenland erosion has exposed large continuous geological sections through volcanic rocks erupted during the early phases of the evolution of the Tertiary North Atlantic Igneous Province. A major finding in a 1994 reconnaissance sampling was the 200 m thick sequence of lava flows recording the C27n-C26r polarity transition (Riisager & Abrahamsen 1999, 2000). We present here paleomagnetic data from a new detailed sampling of two separate profiles offering a uniquely detailed record of a Paleocene geomagnetic transition in lavas. Based on multi-model photogrammetry as well as chemical and lithological analysis of one of the profiles, the 59 lavaflows in the transitional zone can be grouped into 17 magmatic events (eruptions). In general there is a good agreement with magmatic events also showing grouping of the paleomagnetic directions. The C27n-C26r transitional paleomagnetic directions will be presented and the VGP path will be compared to VGP paths of more recent records. References: Riisager, P. & N. Abrahamsen, Geophys. J. Int. 137 (1999) 774-782. Riisager, P. & N. Abrahamsen, Phys. Earth Planet. Inter. 118 (2000) 53-64.