NE Atlantic Breakup and Evolution of the Norwegian-Greenland Conjugate Volcanic Margins

J.I. Faleide¹, F. Tsikalas¹, A.J. Breivik¹, R. Mjelde², J. Wilson¹, and O. Eldholm^2
1Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, N-0316 Oslo, Norway
²Department of Earth Science, University of Bergen, Allegt 41, N-5007 Bergen, Norway

A set of regional transects across the conjugate Norwegian-Greenland margins in NE Atlantic integrated with potential field data and modelling reveal important vertical and lateral variations in crustal configuration and composition associated with continental breakup near the Paleocene-Eocene transition and its preceding phase of extension in Late Cretaceous-Early Tertiary times. The extension culminated with regional uplift and subsequent erosion towards the end of Paleocene, and lithospheric breakup was accompanied by a massive, regional magmatic event, resulting in thick seaward dipping reflector sequences that manifest massive eruptions of lavas covering large areas along the continent-ocean transition. Refinement of the continent-ocean boundary and seafloor spreading anomalies along the conjugate margins provide improved geometrical and azimuthal constraints on early opening plate reconstructions that, in turn, confirm high early opening spreading rates and contribute to a better understanding of the coupling between volcanism and early sea floor spreading. Furthermore, a denser OBS data coverage contributes to a more detailed (3D) mapping of the 7+ km/s lower crustal body volume and distribution in both oceanic and continental crustal domains. Potential field modelling and Vp/Vs ratios from high-quality OBS data provide further constraints on the physical properties and composition of the high-velocity lower crustal body. Therefore, improved constraints can be reached through modelling of various breakup-related processes, such as: regional extension and magmatism (including estimates of volumes and rates); extent and timing of the subsequent continental heating; and the interplay of sedimentation, magmatism and vertical motion. Seismic mapping shows a distinct lateral distribution of breakup-related rocks revealing the influence of the along-strike segmentation and its role in the tectono-magmatic margin evolution. In particular, the Norwegian margin is divided into a series of rifted, sheared, and oblique-segments that appear to have experienced different structural, magmatic and temperature histories. Details on margin physiography during early opening are crucial for understanding the driving force for vertical movements at a local and regional scale.

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands