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