K. Lambeck, GLACIAL REBOUND OF THE BRITISH-ISLES .2. A HIGH-RESOLUTION, HIGH-PRECISION MODEL, Geophysical journal international, 115(3), 1993, pp. 960-990
Observations of ice movements across the British Isles and of sea-leve
l changes around the shorelines during Late Devensian time (after abou
t 25 000 yr BP) have been used to establish a high spatial and tempora
l resolution model for the rebound of Great Britain and associated sea
-level change. The sea-level observations include sites within the mar
gins of the former ice sheet as well as observations outside the glaci
ated regions such that it has been possible to separate unknown earth
model parameters from some ice-sheet model parameters in the inversion
of the glacio-hydro-isostatic equations. The mantle viscosity profile
is approximated by a number of radially symmetric layers representing
the lithosphere, the upper mantle as two layers from the base of the
lithosphere to the phase transition boundary at 400 km, the transition
zone down to 670 km depth, and the lower mantle. No evidence is found
to support a strong layering in viscosity above 670 km other than the
high-viscosity lithospheric layer. Models with a low-viscosity zone i
n the upper mantle or models with a marked higher viscosity in the tra
nsition zone are less satisfactory than models in which the viscosity
is constant from the base of the lithosphere to the 670 km boundary. I
n contrast, a marked increase in viscosity is required across this lat
ter boundary. The optimum effective parameters for the mantle beneath
Great Britain are: a lithospheric thickness of about 65 km, a mantle v
iscosity above 670 km of about (4-5) 10(20) Pa s, and a viscosity belo
w 670 km greater than 4 x 10(21) Pa s.