In search of an ice history that is consistent with composite rheology in Glacial Isostatic Adjustment modelling

Huang, Pingping; Wu, Patrick; Steffen, Holger

doi:10.1016/j.epsl.2019.04.011

Cited by 18 publications

(13 citation statements)

References 45 publications

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“…This is a significant improvement from the

2 °

2 °

of earlier implementations of the method of Wu (2004), including the

0.5 °

0.5 °

spatial resolution from the recent study of Huang et al. (2019). It must be noted that the resolution is lower when compared to the global finite volume models used in Powell et al.…”

Section: Methodsmentioning

confidence: 79%

“…It can be seen in figure 3 of the supplementary material that the deflection underneath and near ice masses differs between the FE model and the benchmark model by 1.3% for a resolution of ± 0.25 • x 0.25 • . This is a significant improvement from the 2 • x 2 • of earlier implementations of the method of (Wu, 2004), including the 0.5 • x 0.5 • spatial resolution from the recent study of Huang et al (2019). It must be noted that the resolution is lower when compared to the global finite volume models used in Powell et al (2020), or local normal mode model, such as Barletta et al (2018) whose grid points are approximately 5 km apart.…”

Section: D Finite Element Modelmentioning

confidence: 93%

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Effect of Lateral and Stress‐Dependent Viscosity Variations on GIA Induced Uplift Rates in the Amundsen Sea Embayment

Blank

Barletta²,

et al. 2021

Geochem Geophys Geosyst

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Accurate GIA models are required for correcting measurements of mass change in Antarctica and for improving knowledge of the sub-surface, especially in areas of large current ice loss such as the Amundsen Sea Embayment(ASE). Regionally, seismic and gravity data suggests lateral differences in viscosity (3D). Furthermore, mantle flow laws allow for a stress-dependent effective viscosity which changes over time (3D-s). In this study we investigate whether models with 3D/3D-s have significant effects on the uplift in the region. We use a finite element model with composite rheology consisting of diffusion and dislocation creep, forced by an ice deglaciation model starting in 1900. We use its uplift predictions as synthetic observations to test the performance of 1D model inversion in the presence of viscosity variations. Stress-dependent rheology results in lower viscosity beneath the load and a more localized uplift pattern. We demonstrate that the background stress from earlier ice load changes can both increase or decrease the influence of stress-induced effective viscosity changes. For the ASE, fitting 1D models to 3D model uplift results in a best fitting model with viscosity that represents the average of a large area, while for 3D-s rheology, local viscosity is more influential. 1D models are statistically indistinguishable from 3D/3D-s viscosity with current GPS stations. However, 3D and 3D-

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“…This is a significant improvement from the

2 °

2 °

of earlier implementations of the method of Wu (2004), including the

0.5 °

0.5 °

spatial resolution from the recent study of Huang et al. (2019). It must be noted that the resolution is lower when compared to the global finite volume models used in Powell et al.…”

Section: Methodsmentioning

confidence: 79%

Section: D Finite Element Modelmentioning

confidence: 93%

Effect of Lateral and Stress‐Dependent Viscosity Variations on GIA Induced Uplift Rates in the Amundsen Sea Embayment

Blank

Barletta²,

et al. 2021

Geochem Geophys Geosyst

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“…This deformation mechanism is consistent with our assumption in the GIA simulations that the mantle deforms like a Newtonian fluid. Nevertheless, it has also been suggested that deformation and flow during GIA may occur via dislocation creep, particularly in locations where strain rates are highest in the comparatively high-homologous-temperature asthenosphere (Huang et al, 2019;van der Wal et al, 2013). The dependence of dislocation creep viscosity on temperature (i.e.…”

Section: Standard Deviation In Viscosity Perturbationsmentioning

confidence: 99%

The effect of lateral variations in Earth structure on Last Interglacial sea level

Austermann

Hoggard

Latychev

et al. 2021

Geophysical Journal International

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Summary It is generally agreed that the Last Interglacial (LIG; ∼130 – 115 ka) was a time when global average temperatures and global mean sea level were higher than they are today. However, the exact timing, magnitude, and spatial pattern of ice melt is much debated. One difficulty in extracting past global mean sea level from local observations is that their elevations need to be corrected for glacial isostatic adjustment (GIA), which requires knowledge of Earth’s internal viscoelastic structure. While this structure is generally assumed to be radially symmetric, evidence from seismology, geodynamics, and mineral physics indicates that large lateral variations in viscosity exist within the mantle. In this study, we construct a new model of Earth’s internal structure by converting shear wave speed into viscosity using parameterisations from mineral physics experiments and geodynamical constraints on Earth’s thermal structure. We use this 3D Earth structure, which includes both variations in lithospheric thickness and lateral variations in viscosity, to calculate the first 3D GIA prediction for LIG sea level. We find that the difference between predictions with and without lateral Earth structure can be meters to 10s of meters in the near field of former ice sheets, and up to a few meters in their far field. We demonstrate how forebulge dynamics and continental levering are affected by laterally varying Earth structure, with a particular focus on those sites with prominent LIG sea level records. Results from four 3D GIA calculations show that accounting for lateral structure can act to increase local sea level by up to ∼1.5 m at the Seychelles and minimally decrease it in Western Australia. We acknowledge that this result is only based on a few simulations, but if robust, this shift brings estimates of global mean sea level from these two sites into closer agreement with each other. We further demonstrate that simulations with a suitable radial viscosity profile can be used to locally approximate the 3D GIA result, but that these radial profiles cannot be found by simply averaging viscosity below the sea level indicator site.

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“…In this paper mantle rheology is assumed to be linear, the effects of nonlinear or composite rheology are considered in Huang et al. (2019), but lie beyond the scope of this study. Here, the parameter

\beta \in [0,\,1]

, which represents the fractional contribution of the thermal effect on seismic anomalies and determines the amplitude of the lateral viscosity variations, and thus non‐thermal effects such as compositional and non‐isotropic pre‐stress effects will consequently have the fractional contribution 1‐ β .…”

Section: Gia Modelingmentioning

confidence: 99%

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

Khan

Baranskaya

et al. 2022

JGR Solid Earth

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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.

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In search of an ice history that is consistent with composite rheology in Glacial Isostatic Adjustment modelling

Cited by 18 publications

References 45 publications

Effect of Lateral and Stress‐Dependent Viscosity Variations on GIA Induced Uplift Rates in the Amundsen Sea Embayment

Effect of Lateral and Stress‐Dependent Viscosity Variations on GIA Induced Uplift Rates in the Amundsen Sea Embayment

The effect of lateral variations in Earth structure on Last Interglacial sea level

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

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