Miocene uplift of the NE Greenland margin linked to plate tectonics: Seismic evidence from the Greenland Fracture Zone, NE Atlantic

Abstract

Tectonic models predict that following breakup, rift margins undergo only decaying thermal subsidence during their postrift evolution. However, postbreakup stratigraphy beneath the NE Atlantic shelves shows evidence of regional-scale unconformities, commonly cited as outer margin responses to inner margin episodic uplift, including the formation of coastal mountains. The origin of these events remains enigmatic. We present a seismic reflection study from the Greenland Fracture Zone-East Greenland Ridge (GFZ-EGR) and the NE Greenland shelf. We document a regional intra-Miocene seismic unconformity (IMU), which marks the termination of synrift deposition in the deep-sea basins and onset of (i) thermomechanical coupling across the GFZ, (ii) basin compression, and (iii) contourite deposition, north of the EGR. The onset of coupling across the GFZ is constrained by results of 2-D flexural backstripping. We explain the thermomechanical coupling and the deposition of contourites by the formation of a continuous plate boundary along the Mohns and Knipovich ridges, leading to an accelerated widening of the Fram Strait. We demonstrate that the IMU event is linked to onset of uplift and massive shelf progradation on the NE Greenland margin. Given an estimated middle to late Miocene (~15-10 Ma) age of the IMU, we speculate that the event is synchronous with uplift of the east and west Greenland margins. The correlation between margin uplift and plate motion changes further indicates that the uplift was triggered by plate tectonic forces, induced perhaps by a change in the Iceland plume (a hot pulse) and/or by changes in intraplate stresses related to global tectonics.

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

“…The low‐velocity anomalies from CE Greenland are consistent with previous P and S waves tomography (Jakovlev et al, ; Lebedev et al, ; Mordret, ; Rickers et al, ; Schaeffer & Lebedev, , ) and with indications of lithospheric thinning in this region (Kumar et al, ; Schiffer et al, ). The presence of this mantle low‐velocity anomaly in a region of documented postrift uplift (Anell et al, ; Døssing et al, ; Japsen & Chalmers, ) and unusually high GIA uplift rates (e.g., +10 mm/year; Khan et al, ) could also be an evidence of low upper mantle viscosity and explain the mechanism for isostatic compensation in a region with no deep crustal roots. The lack of a similar velocity low beneath the western Tertiary Basalt Province in this depth range could indicate limited lithospheric modifications from the failed rifting of the Labrador Sea.…”

Frenulate siboglinids at high Arctic methane seeps and insight into high latitude frenulate distribution

“…Furthermore, siboglinids, even if not frenulates themselves, are included in this calculation. The divergence date range we suggest corresponds with the late Neogene, a period which was characterized by both uplift and accelerated subsidence in the Nordic seas and Fram Strait (e.g., Døssing et al, ; Japsen & Chalmers, ; Knies & Gaina, ). The resulting changes in the seafloor topography could have limited exchanges between populations or even isolation of some, which could have led to species being defined by bathymetry, in correspondence with present‐day distributions which appear to be constrained by water depth.…”

“…Exchange with Atlantic water started well before, with the opening of the Fram Strait around 17.5 Ma (Jakobsson et al, ) and variable overflows over the Greenland–Scotland Ridge beginning around 12 Ma (Poore, Samworth, White, Jones, & McCave, ). However, events that occurred later, such as deepening and stabilization of the Greenland–Scotland Ridge 6–2 Ma (Poore et al, ) and widening of the Fram Strait at 10 Ma, led to more steady and escalated water exchange as well as bottom current activity (Døssing et al, ; Kristoffersen, ). A later further deepening and widening of the Fram Strait occurred at 6–5 Ma, which caused additional intensification of the North Atlantic thermohaline circulation (Knies et al, ) and resulted in a highly stratified water column in the Nordic seas, as is seen today.…”

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.…”