Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland
Contemporary crustal uplift and relative sea level change in Greenland is caused by the response of the solid Earth to ongoing and historical ice mass change. Glacial isostatic adjustment (GIA) models, which seek to match patterns of land surface displacement and relative sea level change, typically...
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:37983 2023-05-15T16:26:28+02:00 Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland Paxman, G.J.G. Lau, H.C.P. Austermann, J. Holtzman, B.K. Havlin, C. 2023 application/pdf http://dro.dur.ac.uk/37983/ http://dro.dur.ac.uk/37983/1/37983.pdf https://agupubs.onlinelibrary.wiley.com/journal/2576604x unknown Wiley dro:37983 issn:2576-604X http://dro.dur.ac.uk/37983/ https://agupubs.onlinelibrary.wiley.com/journal/2576604x http://dro.dur.ac.uk/37983/1/37983.pdf AGU Advances, 2023 [Peer Reviewed Journal] Article PeerReviewed 2023 ftunivdurham 2023-02-16T23:26:13Z Contemporary crustal uplift and relative sea level change in Greenland is caused by the response of the solid Earth to ongoing and historical ice mass change. Glacial isostatic adjustment (GIA) models, which seek to match patterns of land surface displacement and relative sea level change, typically employ a linear Maxwell viscoelastic model for the Earth’s mantle. In Greenland, however, upper mantle viscosities inferred from ice load changes and other geophysical phenomena occurring over a range of timescales vary by up to two orders of magnitude. Here, we use full-spectrum rheological models to examine the influence of transient deformation within the Greenland upper mantle, which may account for these differing viscosity estimates. We use observations of shear wave velocity combined with constitutive rheological models to self-consistently calculate mechanical properties including the apparent upper mantle viscosity and lithosphere thickness across a broad spectrum of frequencies. We find that the contribution of transient behaviour is most significant over loading timescales of 102–103 years, which corresponds to the timeframe of ice mass loss over recent centuries. Predicted apparent lithosphere thicknesses are also in good agreement with inferences made across seismic, GIA, and flexural timescales. Our results indicate that full-spectrum constitutive models that more fully capture broadband mantle relaxation provide a means of reconciling seemingly contradictory estimates of Greenland’s upper mantle viscosity and lithosphere thickness made from observations spanning a range of timescales. Article in Journal/Newspaper Greenland Durham University: Durham Research Online Greenland |
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Durham University: Durham Research Online |
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Contemporary crustal uplift and relative sea level change in Greenland is caused by the response of the solid Earth to ongoing and historical ice mass change. Glacial isostatic adjustment (GIA) models, which seek to match patterns of land surface displacement and relative sea level change, typically employ a linear Maxwell viscoelastic model for the Earth’s mantle. In Greenland, however, upper mantle viscosities inferred from ice load changes and other geophysical phenomena occurring over a range of timescales vary by up to two orders of magnitude. Here, we use full-spectrum rheological models to examine the influence of transient deformation within the Greenland upper mantle, which may account for these differing viscosity estimates. We use observations of shear wave velocity combined with constitutive rheological models to self-consistently calculate mechanical properties including the apparent upper mantle viscosity and lithosphere thickness across a broad spectrum of frequencies. We find that the contribution of transient behaviour is most significant over loading timescales of 102–103 years, which corresponds to the timeframe of ice mass loss over recent centuries. Predicted apparent lithosphere thicknesses are also in good agreement with inferences made across seismic, GIA, and flexural timescales. Our results indicate that full-spectrum constitutive models that more fully capture broadband mantle relaxation provide a means of reconciling seemingly contradictory estimates of Greenland’s upper mantle viscosity and lithosphere thickness made from observations spanning a range of timescales. |
format |
Article in Journal/Newspaper |
author |
Paxman, G.J.G. Lau, H.C.P. Austermann, J. Holtzman, B.K. Havlin, C. |
spellingShingle |
Paxman, G.J.G. Lau, H.C.P. Austermann, J. Holtzman, B.K. Havlin, C. Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
author_facet |
Paxman, G.J.G. Lau, H.C.P. Austermann, J. Holtzman, B.K. Havlin, C. |
author_sort |
Paxman, G.J.G. |
title |
Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
title_short |
Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
title_full |
Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
title_fullStr |
Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
title_full_unstemmed |
Inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath Greenland |
title_sort |
inference of the timescale-dependent apparent viscosity structure in the upper mantle beneath greenland |
publisher |
Wiley |
publishDate |
2023 |
url |
http://dro.dur.ac.uk/37983/ http://dro.dur.ac.uk/37983/1/37983.pdf https://agupubs.onlinelibrary.wiley.com/journal/2576604x |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
AGU Advances, 2023 [Peer Reviewed Journal] |
op_relation |
dro:37983 issn:2576-604X http://dro.dur.ac.uk/37983/ https://agupubs.onlinelibrary.wiley.com/journal/2576604x http://dro.dur.ac.uk/37983/1/37983.pdf |
_version_ |
1766015381024014336 |