Influence of 3D Earth Structure on Glacial Isostatic Adjustment in the Russian Arctic

What is it about?

The western Russian Arctic was partially covered by the Eurasian ice sheet complex during the Last Glacial Maximum (∼26 ka BP) and is a focus area for understanding the response of the solid Earth to ice loading and unloading events, known as glacial isostatic adjustment (GIA). We use a database containing standardized relative sea-level (RSL) data to validate one-dimensional (1D; laterally homogeneous) GIA models and test new three-dimensional (3D; laterally heterogeneous) GIA models. We find that 1D models fit the RSL data along the southern coast of Barents Sea and Franz-Josef-Land but show significant misfits with the RSL data in the White Sea region. We find the optimal 3D model improves the fit around the White Sea region while retaining good fits achieved by 1D models. Our results reveal deglacial RSL changes are (a) sensitive to laterally varying lithosphere and viscosity structure in the upper mantle in the western Russian Arctic; and (b) insensitive to viscosity structure in the lower mantle compared to the upper mantle in the Russian Artic. Furthermore, we notice that 3D GIA models with different background 1D viscosities and lateral viscosity variations can provide similar fit with the RSL data.

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