The NE-Atlantic challenge: where should we core and where should we conduct a wide-angle seismic survey?

The Northeast Atlantic area presents new fundamental challenges in geodynamics, making it a superb international laboratory to develop new models and concepts that can be tested elsewhere. Among the most exciting challenges in this area is characterization of the different types of crust that may be encountered in oceanic realms. Viewing this area objectively, it appears that the classical distinction between oceanic and continental lithosphere is no longer adequate to interpret contemporary observations. This is a direct consequence of the huge input of magma into the lithosphere that has occurred at different stages of its evolution. Notably, we do not fully understand the true nature of the crust beneath Iceland and along the nearby continental margins and aseismic ridges (e.g., the GIFR). In particular, the classical distinctions made from linear magnetic anomalies (LMA) to distinguish oceanic and continental lithosphere is proven to not work. Massive magmatic-type accretion may occur together with continental thinning and stretching to generate symmetrical LMA over wide continental domains and give rise to erroneous interpretations as oceanic-type lithosphere. If part of the crust is inherited from former, albeit transformed, continental crust, this must also apply to the underlying mantle lithosphere. For example, old slabs may be trapped and reworked in the lithosphere and play major roles in its evolution. These new considerations have fundamental economic, political and scientific implications. It is now urgent to target and investigate the true nature of the crust in the NE-Atlantic, in particular seeking clues to the existence of continental material in specific areas. In my presentation I will make specific proposals.