A possible glacially-forced tectonic mechanisms for late Neogene surface uplift and subsidence around the North Atlantic

Analysis of old erosion surfaces and estimates of exhumation from apatite fission track data can be used
to infer late Neogene surface uplift of Britain, Greenland, Norway and Svalbard of 1–2 km. Subsidence
and sedimentation in adjacent offshore basins can be found from interpretation of seismic and well log
data. Various mechanisms for surface uplift have been proposed but the underlying cause remains
unexplained. Since the multiple glaciations that took place during the late Neogene were a common
factor, a possible glacially-forced tectonic mechanism to thicken the crust and produce surface uplift has
been investigated. This could result from the relatively slow accumulation of ice that loads the crust as an
ice sheet grows during a glacial period, followed by relatively rapid retreat and unloading around its
periphery at the end. Unloading could create transient stresses that induce lateral flow in a ductile lower
crust to thicken it onshore and produce surface uplift, with associated thinning beneath adjacent
offshore basins, producing subsidence. Simple calculations show that the proposed mechanism is
feasible and indicate that crustal thickening and surface uplift accumulated from a number of glacial
cycles can account for the observed surface uplift, with an acceptable flow rate in the lower crust at the
end of each cycle if the viscosity of ductile flow is sufficiently low.