Localization of the gravity field and the signature of glacial rebound
The negative free-air gravity anomaly centred on Hudson Bay, Canada, shows a remarkable correlation with the location of the Laurentide ice sheet, suggesting that this gravity anomaly is the result of incomplete post-glacial rebound. This region, however, is also underlain by higher-than-average man...
Published in: | Nature |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Nature Publishing Group
1997
|
Subjects: | |
Online Access: | https://authors.library.caltech.edu/38876/ https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743 |
id |
ftcaltechauth:oai:authors.library.caltech.edu:38876 |
---|---|
record_format |
openpolar |
spelling |
ftcaltechauth:oai:authors.library.caltech.edu:38876 2023-05-15T16:13:01+02:00 Localization of the gravity field and the signature of glacial rebound Simons, Mark Hager, Bradford H. 1997-12-04 https://authors.library.caltech.edu/38876/ https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743 unknown Nature Publishing Group Simons, Mark and Hager, Bradford H. (1997) Localization of the gravity field and the signature of glacial rebound. Nature, 390 (6659). pp. 500-504. ISSN 0028-0836. doi:10.1038/37339. https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743 <https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743> Article PeerReviewed 1997 ftcaltechauth https://doi.org/10.1038/37339 2021-11-11T18:54:01Z The negative free-air gravity anomaly centred on Hudson Bay, Canada, shows a remarkable correlation with the location of the Laurentide ice sheet, suggesting that this gravity anomaly is the result of incomplete post-glacial rebound. This region, however, is also underlain by higher-than-average mantle seismic velocities, suggesting that the gravity low might result instead from dynamic topography associated with convective downwellings. Here we analyse the global gravity field as a simultaneous function of geographic location and spectral content. We find that the Hudson Bay gravity low is unique, with anomalously high amplitude in the spectral band where the power from the Laurentide ice load is greatest and the relaxation times predicted for viable models of viscous relaxation are longest. We estimate that about half of the Hudson Bay gravity anomaly is the result of incomplete post-glacial rebound, and derive a mantle viscosity model that explains both this gravity signature and the characteristic uplift rates for the central Laurentide and Fennoscandian regions. This model has a jump in viscosity at 670 km depth, comparable to that in dynamic models of the geoid highs over subducted slabs, but lacks a low-viscosity asthenosphere, consistent with a higher viscosity in the upper mantle beneath shields than in oceanic regions. Article in Journal/Newspaper Fennoscandian Hudson Bay Ice Sheet Caltech Authors (California Institute of Technology) Canada Hudson Hudson Bay Nature 390 6659 500 504 |
institution |
Open Polar |
collection |
Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
unknown |
description |
The negative free-air gravity anomaly centred on Hudson Bay, Canada, shows a remarkable correlation with the location of the Laurentide ice sheet, suggesting that this gravity anomaly is the result of incomplete post-glacial rebound. This region, however, is also underlain by higher-than-average mantle seismic velocities, suggesting that the gravity low might result instead from dynamic topography associated with convective downwellings. Here we analyse the global gravity field as a simultaneous function of geographic location and spectral content. We find that the Hudson Bay gravity low is unique, with anomalously high amplitude in the spectral band where the power from the Laurentide ice load is greatest and the relaxation times predicted for viable models of viscous relaxation are longest. We estimate that about half of the Hudson Bay gravity anomaly is the result of incomplete post-glacial rebound, and derive a mantle viscosity model that explains both this gravity signature and the characteristic uplift rates for the central Laurentide and Fennoscandian regions. This model has a jump in viscosity at 670 km depth, comparable to that in dynamic models of the geoid highs over subducted slabs, but lacks a low-viscosity asthenosphere, consistent with a higher viscosity in the upper mantle beneath shields than in oceanic regions. |
format |
Article in Journal/Newspaper |
author |
Simons, Mark Hager, Bradford H. |
spellingShingle |
Simons, Mark Hager, Bradford H. Localization of the gravity field and the signature of glacial rebound |
author_facet |
Simons, Mark Hager, Bradford H. |
author_sort |
Simons, Mark |
title |
Localization of the gravity field and the signature of glacial rebound |
title_short |
Localization of the gravity field and the signature of glacial rebound |
title_full |
Localization of the gravity field and the signature of glacial rebound |
title_fullStr |
Localization of the gravity field and the signature of glacial rebound |
title_full_unstemmed |
Localization of the gravity field and the signature of glacial rebound |
title_sort |
localization of the gravity field and the signature of glacial rebound |
publisher |
Nature Publishing Group |
publishDate |
1997 |
url |
https://authors.library.caltech.edu/38876/ https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743 |
geographic |
Canada Hudson Hudson Bay |
geographic_facet |
Canada Hudson Hudson Bay |
genre |
Fennoscandian Hudson Bay Ice Sheet |
genre_facet |
Fennoscandian Hudson Bay Ice Sheet |
op_relation |
Simons, Mark and Hager, Bradford H. (1997) Localization of the gravity field and the signature of glacial rebound. Nature, 390 (6659). pp. 500-504. ISSN 0028-0836. doi:10.1038/37339. https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743 <https://resolver.caltech.edu/CaltechAUTHORS:20130610-102157743> |
op_doi |
https://doi.org/10.1038/37339 |
container_title |
Nature |
container_volume |
390 |
container_issue |
6659 |
container_start_page |
500 |
op_container_end_page |
504 |
_version_ |
1765998627161899008 |