Lateral asthenospheric viscosity variations and postglacial rebound: A case study for the Barents Sea

Abstract

Abstract.The effect of lateral asthenospheric viscosity variations on observable signatures related to postglacial rebound in the Barents Sea is studied. Using a finite-element approach to discretize the problem, a comparison between a laterally homogeneous reference earth model and a laterally heterogeneous earth model is performed.The results indicate that a change in asthenospheric viscosity of about three orders of magnitude influences predictions of land uplift up to 10-20 m, present-day velocities up to 0.5-1.5 mm/a, and present-day gravity anomalies up to 0.4 -0.8 mGal in the northwestern part of the Barents Sea region.

The effect of sediment loading in Fennoscandia and the Barents Sea during the last glacial cycle on glacial isostatic adjustment observations

“…The eastern part of Scandinavia is part of a craton, which manifests itself in large crustal thickness and higher seismic velocities, which extend to the Barents Sea as seen in seismic measurements (see, e.g., Schaeffer and Lebedev, 2013). The large seismic velocities likely result from high viscosity underneath eastern Scandinavia and the Barents Sea (e.g., van der Wal et al, 2013), which could reduce the present-day uplift rate in east Scandinavia and the Barents Sea (Kaufmann and Wu, 1998) but could increase the uplift rate west of Norway.…”

Constraints on Glacial Isostatic Adjustment from GOCE and Sea Level Data

“…He found an average viscosity of 4 9 10 19 PaÁs and a thickness of 75 km, but with large regional variations (CATHLES, 1975, p. 270). Regionally, a study of KAUFMANN and WU (1998) for the Barents Sea assumes a 110-km thick lithosphere and a lateral variation in asthenospheric viscosity from 10 18 to 10 21 PaÁs. A study for northern Europe by KAUFMANN and WU (2002) assumes, based on seismological evidence and estimates from seismic tomography, variations in lithospheric thickness (from 90 km in oceanic areas to 170 km under cratons) and asthenospheric viscosity (10 18 PaÁs in the oceanic areas).…”

Modelling the influence of glacial isostasy on Late Weichselian ice-sheet growth in the Barents Sea

“…In practice this assumption is unlikely to hold near the edge of the continental shelf, where the transition between continental and oceanic plates occurs. However, Kaufmann and Wu (1998) suggest that this transition zone lies within 200 km of the continental margin. Therefore, our assumption of a constant asthenospheric viscosity (and hence a single characteristic time constant) is reasonable for the central and eastern parts of the Barents Sea.…”

“…Therefore, our assumption of a constant asthenospheric viscosity (and hence a single characteristic time constant) is reasonable for the central and eastern parts of the Barents Sea. We note, however, that caution must be taken in interpreting model results near the continental margin because our isostatic model does not consider the dynamic effects on the lithosphere of the change from continental to oceanic plates and asthenosphere (Kaufmann and Wu, 1998). …”