A review of the NE Atlantic conjugate margins based on seismic refraction data

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 21 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.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

Lithospheric Structure of Greenland From Ambient Noise and Earthquake Surface Wave Tomography

“…Compatibility between our model and more localized thickness estimates is variable along the continental margins. Crustal thickness variations along the SW and SE margins are in relatively good agreement with seismic refraction and reflection profiles that estimate thickness ranging from~30 km in the southwest (Chian & Louden, 1992) to 30-35 km in the southeast (Funck et al, 2017;Hopper et al, 2003;Korenaga et al, 2000). Our model is also in relatively good agreement with the receiver function estimates of Schiffer et al (2015) in the Central Fjord Region of East Greenland (73°N) where crustal thickness is thought to increase from~25 km (22°W) to~40 km (29°W) toward the center of the Caledonian high topography.…”

“…A likely tectonic and structural boundary has been previously identified in western (van Gool, Connelly, et al, 2002;Wardle et al, 2000) and eastern Greenland (Brooks, 2011;Escher & Pulvertaft, 1995;Hamann et al, 2005;Henriksen et al, 2008Henriksen et al, , 2009Koch & Haller, 1971;Larsen, 1990) where the crystalline crust is composed primarily of Archean and reworked Archean rocks to the south of this boundary and Paleoproterozoic rocks to the north. The importance of this boundary on the eastern margin is also suggested by persistent differences in geological evolution, including in late Paleozoic and Mesozoic rift basin formation and sediment deposition (Henriksen et al, 2008;Stemmerik et al, 2013;Surlyk, 1990;Tsikalas et al, 2005) and in styles of magmatic emplacement (Funck et al, 2017;Schlindwein & Jokat, 1999;Schmidt-Aursch & Jokat, 2005). A similar SW-NE boundary separating regions of different crustal thickness has also been inferred from receiver function and gravity studies (Dahl-Jensen, Petrov et al, 2016;Steffen et al, 2017).…”

“…Active and passive geophysical experiments have been conducted both offshore and onshore Greenland to better constrain the tectonic framework of its interior. A synthesis of geological (Brooks, 2011;Dawes, 2009;Escher & Pulvertaft, 1995;Hamann et al, 2005;Henriksen et al, 2008Henriksen et al, , 2009Koch & Haller, 1971;Larsen et al, 2014;Roberts & Bally, 2012) and geophysical (Funck et al, 2017;Hermann & Jokat, 2016;Schiffer et al, 2015;Schlindwein & Jokat, 1999;Schmirdt-Aursch & Jokat, 2005;Tsikalas et al, 2005;Voss & Jokat, 2007;Voss et al, 2009) studies of the east Greenland margin and shelf identifies pronounced differences in the crustal structure and tectonic evolution north and south of the Kong Oscar Fjord (~73°N, Figure 1), including the presence of magmatic underplating and limited extrusion in the north versus large flood basalt provinces and no underplating in the south. Onshore and offshore active seismic profiles in south Greenland (Alsulami et al, 2015;Chian & Louden, 1992Dahl-Jensen et al, 1998;Holbrook et al, 2001;Hopper et al, 2003;Keen et al, 2012;Larsen, 1990;Nielsen et al, 2002) also show contrasting styles of rifted margins from amagmatic to the southwest to volcanic to the southeast.…”

The NE Atlantic region: a reappraisal of crustal structure, tectonostratigraphy and magmatic evolution – an introduction to the NAG-TEC project

“…Based on this first-order compilation, and on additional information from the seismic refraction compilation (see Funck et al 2014), the model presented by Haase et al (2016) offers a 3D perspective of the basement and Moho geometries in the NE Atlantic that permits an improved resolution of some areas, such as basins along the NE Greenland margin, as well as the GIFRC. The maps generated are particularly useful in areas with poor seismic data coverage, in particular where the Moho and basement maps obtained from the seismic refraction database are very coarse and lack detailed structure (Funck et al 2016a).…”

Crustal Structure in Central‐Eastern Greenland From Receiver Functions

“…The geological and geophysical knowledge of interior Greenland is very limited, because more than 80% of the area is covered by the up to 3.4‐km‐thick ice sheet (Figure ). This leads to challenging conditions for geophysical fieldwork and previous studies were controlled‐source experiments conducted offshore on the continental margin and at the continent‐ocean transition (e.g., Chian & Louden, ; Dahl‐Jensen et al, ; Døssing et al, ; Funck et al, ; Holbrook et al, ; Hopper et al, ; Kvarven et al, ; Schlindwein & Jokat, ; Voss et al, ; Voss & Jokat, ) and on the ice‐free onshore parts (Voss et al, ; Hermann & Jokat, ; for an overview, see Artemieva & Thybo, ). The GLATIS project (Dahl‐Jensen et al, ) was the first seismological study to include the ice‐covered interior of continental Greenland.…”