HR: 0830h
AN: T51F-0215    [PDF]
TI: Bivrost Transfer System: A Primary Cross-margin Tectono-magmatic Feature on the Norwegian-Greenland Margin
AU: * Eldholm, O
EM: olav.eldholm@geo.uib.no
AF: Department of Earth Science, University of Bergen, Allegt 41, Bergen, N-5007 Norway
AU: Tsikalas, F
EM: filippos.tsikalas@geo.uio.no
AF: Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, Oslo, N-0316 Norway
AU: Faleide, J I
EM: j.i.faleide@geo.uio.no
AF: Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, Oslo, N-0316 Norway
AB: The Norway-East Greenland conjugate margin exhibits distinct along-strike segmentation. The Jan Mayen and Senja fracture zones and their landward prolongations represent first-order features. In between, we identify several second- and third-order features. Of these, the Bivrost transfer system is the most prominent. Off Norway, it separates two different physiographic provinces, i.e. the V{\o}ring and Lofoten-Vester{\aa}len margins. Structural studies, analysis of potential field images on the conjugate margins, and plate reconstructions to early Tertiary opening suggest a landward prolongation of the Bivrost Fracture Zone on both margins. The prolongations appear as low-relief Late Jurassic-Early Cretaceous accommodation zones, reactivated during Late Cretaceous-Paleocene rifting. We recognize a difference in trend, and possibly in polarity, of the relative motion between the older transfer zone and the younger fracture zone. The more northerly sinistral relative motion along the fracture zone suggests two different stress regimes, however the older feature may have determined the initial location of the fracture zone. Pre-opening structural spatial relations may imply sinistral offsets also along the continental prolongations. Furthermore, we observe a northward decrease in thickness and volume of the high-velocity lower crust, interpreted as related to magmatic underplating, across the Bivrost Fracture Zone. Other changes north of the fracture zone include: breakup lavas over most of the continental slope, a reduction in the intensity of sill intrusions, and a change in style of the seaward dipping seismic reflector images to less prominent and shallower features without the typical, deep wedge-like pattern observed to the south. We interpret breakup occurring in different crustal configurations: in the south along the western flank of the deep Cretaceous V{\o}ring Basin, and in the north along a deep-rooted detachment fault in relatively thick crust on the eastern basin flank. These settings have governed the asymmetric distribution of breakup magmatism and the construction of marginal highs.
DE: 8105 Continental margins and sedimentary basins
DE: 9325 Atlantic Ocean
SC: Tectonophysics [T]
MN: 2003 Fall Meeting