Abstract
Abstract The NE Atlantic region evolved through several rift episodes, leading to break-up in the Eocene that was associated with voluminous magmatism along the conjugate margins of East Greenland and NW Europe. Existing seismic refraction data provide good constraints on the overall tectonic development of the margins, despite data gaps at the NE Greenland shear margin and the southern Jan Mayen microcontinent. The maximum thickness of the initial oceanic crust is 40 km at the Greenland–Iceland–Faroe Ridge, but decreases with increasing distance to the Iceland plume. High-velocity lower crust interpreted as magmatic underplating or sill intrusions is observed along most margins but disappears north of the East Greenland Ridge and the Lofoten margin, with the exception of the Vestbakken Volcanic Province at the SW Barents Sea margin. South of the narrow Lofoten margin, the European side is characterized by wide margins. The opposite trend is seen in Greenland, with a wide margin in the NE and narrow margins elsewhere. The thin crust beneath the basins is generally underlain by rocks with velocities of >7 km s −1 interpreted as serpentinized mantle in the Porcupine and southern Rockall basins; while off Norway, alternative interpretations such as eclogite bodies and underplating are also discussed.
Highlights
The opening of the NE Atlantic Ocean between East Greenland and NW Europe created mainly magmarich margins, with exception of the northernmost area at the shear margin between Svalbard/SW Barents Sea and NE Greenland (Fig. 1)
The NE Atlantic region evolved through several rift episodes, leading to break-up in the Eocene that was associated with voluminous magmatism along the conjugate margins of East Greenland and NW Europe
Magmatism associated with the North Atlantic Igneous Province began at 61 Ma and continued throughout the break-up phase (Storey et al 2007), which resulted in magma-rich continental margins extending over a length of 2000 km on either side of the ocean (Fig. 1)
Summary
The NE Atlantic Ocean evolved from the Palaeogene break-up of an amalgamated landmass composed of Avalonia, Baltica and Laurentia that had formed the vast Caledonian mountain chain (Ziegler 1988). North of the Greenland and Senja fracture zones, little volcanism is observed and restricted to the southernmost part (a Horni et al 2014, this volume, in review) This includes the Vestbakken Volcanic Province on the Norwegian side of the margin, where sills intruded into Eocene sediments (Faleide et al 1988; Ryseth et al 2003). In the paper by White & Smith (2009), the COT was defined as the zone where a seaward increase in the average lower-crustal velocity is observed, indicating magmatic intrusions into older, seismically slower crust. North of the Jan Mayen Fracture Zone up to the Senja margin (Fig. 1), the conjugate COBs of Funck et al (2014) match within 20 km upon closure. The COBs of the northern JMMC and the Møre margin fit within 10 km, while the largest misfit of up to 70 km is observed south of Iceland
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