Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling
Observations of glacial isostatic adjustment (GIA) offers a powerful window into the properties of the Earth's interior. Combined with dynamical modeling of the GIA process we can use the observations to infer properties such as the elastic structure of the lithosphere, the rheology of the mant...
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ftuppsalauniv:oai:DiVA.org:uu-169790 2023-05-15T16:12:15+02:00 Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling Schmidt, Peter 2012 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169790 eng eng Uppsala universitet, Geofysik Uppsala Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 906 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169790 urn:isbn:978-91-554-8294-7 info:eu-repo/semantics/openAccess Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2012 ftuppsalauniv 2023-02-23T21:42:54Z Observations of glacial isostatic adjustment (GIA) offers a powerful window into the properties of the Earth's interior. Combined with dynamical modeling of the GIA process we can use the observations to infer properties such as the elastic structure of the lithosphere, the rheology of the mantle and changes in the stress conditions in the Earth. This information aids our understanding of the long term evolution of the Earth, e.g. mantle convection, but also illuminates short term processes such as magma generation, earthquakes and shoreline migration. As present day warming trends causes glacier retreat world wide, GIA offers the opportunity to gain local insight into the Earth. In this thesis I develop an implementation of the pre-stress advection term in finite element modeling. I apply this to current GIA in Iceland, and conclude that local variations in the elastic thickness of the lithosphere can potentially be detected close to the largest ice cap. I study the magnitude of dehydration stiffening in the uppermost Icelandic mantle. The results indicate that the increase in viscosity over the dry solidus is of small magnitude, implying a non-linear rheology in the uppermost mantle beneath Iceland. The present deglaciation in Iceland causes additional melting of the mantle. I find an increased melt production rate of 100-140% at present, although the melt supply rate at the base of the lithosphere is found to be delayed, with estimated present day perturbations ranging from neglible up to 120%. In the last section of the thesis I focus on the role of ice sheet reconstructions in GIA modeling. I compare three reconstruction of the Weichselian ice sheet and discuss similarities and difference as well as the fit to present day uplift rates in Fennoscandia. The results provide input to improvements in the ice sheet models. Doctoral or Postdoctoral Thesis Fennoscandia glacier Ice cap Ice Sheet Iceland Uppsala University: Publications (DiVA) |
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Uppsala University: Publications (DiVA) |
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ftuppsalauniv |
language |
English |
description |
Observations of glacial isostatic adjustment (GIA) offers a powerful window into the properties of the Earth's interior. Combined with dynamical modeling of the GIA process we can use the observations to infer properties such as the elastic structure of the lithosphere, the rheology of the mantle and changes in the stress conditions in the Earth. This information aids our understanding of the long term evolution of the Earth, e.g. mantle convection, but also illuminates short term processes such as magma generation, earthquakes and shoreline migration. As present day warming trends causes glacier retreat world wide, GIA offers the opportunity to gain local insight into the Earth. In this thesis I develop an implementation of the pre-stress advection term in finite element modeling. I apply this to current GIA in Iceland, and conclude that local variations in the elastic thickness of the lithosphere can potentially be detected close to the largest ice cap. I study the magnitude of dehydration stiffening in the uppermost Icelandic mantle. The results indicate that the increase in viscosity over the dry solidus is of small magnitude, implying a non-linear rheology in the uppermost mantle beneath Iceland. The present deglaciation in Iceland causes additional melting of the mantle. I find an increased melt production rate of 100-140% at present, although the melt supply rate at the base of the lithosphere is found to be delayed, with estimated present day perturbations ranging from neglible up to 120%. In the last section of the thesis I focus on the role of ice sheet reconstructions in GIA modeling. I compare three reconstruction of the Weichselian ice sheet and discuss similarities and difference as well as the fit to present day uplift rates in Fennoscandia. The results provide input to improvements in the ice sheet models. |
format |
Doctoral or Postdoctoral Thesis |
author |
Schmidt, Peter |
spellingShingle |
Schmidt, Peter Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
author_facet |
Schmidt, Peter |
author_sort |
Schmidt, Peter |
title |
Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
title_short |
Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
title_full |
Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
title_fullStr |
Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
title_full_unstemmed |
Glacial Isostatic Adjustment : Inferences on properties and processes in the upper mantle from 3D dynamical modeling |
title_sort |
glacial isostatic adjustment : inferences on properties and processes in the upper mantle from 3d dynamical modeling |
publisher |
Uppsala universitet, Geofysik |
publishDate |
2012 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169790 |
genre |
Fennoscandia glacier Ice cap Ice Sheet Iceland |
genre_facet |
Fennoscandia glacier Ice cap Ice Sheet Iceland |
op_relation |
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 906 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-169790 urn:isbn:978-91-554-8294-7 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1765997519152611328 |