Influence of 3D Earth Structure on Glacial Isostatic Adjustment in the Russian Arctic. Issue 3 (18th March 2022)

• Record Type: Journal Article
• Authors: Li, Tanghua; Khan, Nicole S.; Baranskaya, Alisa V.; Shaw, Timothy A.; Peltier, W. Richard; Stuhne, Gordan R.; Wu, Patrick; Horton, Benjamin P.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-18
• Subjects: glacial isostatic adjustment -- lateral heterogeneity -- mantle rheology -- sea‐level change -- Russian Arctic -- deglaciation history; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2021JB023631
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Analyses of glacial isostatic adjustment (GIA) and deglacial relative sea‐level (RSL) change in the Russian Arctic deliver important insights into the Earth's viscosity structure and the deglaciation history of the Eurasian ice sheet complex. Here, we validate the 1D GIA models ICE‐6G_C (VM5a) and ICE‐7G_NA (VM7) and select new 3D GIA models in the Russian Arctic against a quality‐controlled deglacial RSL database of >500 sea‐level data points from 24 regions. Both 1D models correspond to the RSL data along the southern coast of the Barents Sea and Franz Josef Land from ∼11 ka BP to present but show notable misfits (>50 m at 10 ka BP) with the White Sea data. We find 3D model predictions of deglacial RSL resolve most of the misfits with the observed data for the White Sea while retaining comparable fits in other regions of the Russian Arctic. Our results further reveal: (a) RSL in the western Russian Arctic is sensitive to elastic lithosphere with lateral thickness variation and 3D viscosity structure in the upper mantle; and (b) RSL in the whole Russian Arctic is less sensitive to 3D viscosity structure in the lower mantle compared to the upper mantle. The 3D models reveal a compromise in the upper mantle between the background viscosity and scaling factor to best fit the RSL data, which needs to be considered in future 3D GIA studies. Plain Language Summary: 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. Key Points: We validate 1D GIA models ICE‐6G_C (VM5a) and ICE‐7G_NA (VM7) and test new 3D GIA models with a deglacial RSL database in the Russian Arctic The optimal 3D model retains the good fits achieved by 1D models and considerably improves the fits where 1D models show notable misfits The 3D models reveal a moderate compromise in the upper mantle between the background viscosity and scaling factor to best fit the RSL data