Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States
The deformation pattern of the paleoshorelines of extinct Lake Bonneville were among the first features to indicate that Earth's interior responds viscoelastically to changes in surface loads (Gilbert, 1885). Here we revisit and extend this classic study of isostatic rebound with updated lake c...
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ftcdlib:oai:escholarship.org/ark:/13030/qt5vn6d215 2023-05-15T16:39:53+02:00 Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States Austermann, J Chen, CY Lau, HCP Maloof, AC Latychev, K 2020-02-15 application/pdf https://escholarship.org/uc/item/5vn6d215 unknown eScholarship, University of California qt5vn6d215 https://escholarship.org/uc/item/5vn6d215 public Lake Bonneville Lake Lahontan paleoshorelines glacial isostatic adjustment mantle viscosity Laurentide ice sheet Geochemistry & Geophysics Physical Sciences Earth Sciences article 2020 ftcdlib 2021-06-28T17:07:31Z The deformation pattern of the paleoshorelines of extinct Lake Bonneville were among the first features to indicate that Earth's interior responds viscoelastically to changes in surface loads (Gilbert, 1885). Here we revisit and extend this classic study of isostatic rebound with updated lake chronologies for Lake Bonneville and Lake Lahontan as well as revised elevation datasets of shoreline features. The first order domal pattern in the shoreline elevations can be explained by rebound associated with the removal of the lake load. We employ an iterative scheme to calculate the viscoelastic lake rebound, which accounts for the deformation of the solid Earth and gravity field, to calculate a lake load that is consistent with the load-deformed paleotopography. We find that the domal deformation requires a regional Earth structure that exhibits a thin elastic thickness of the lithosphere (15–25 km) and low sublithospheric Maxwell viscosity (∼1019 Pa s). After correcting for rebound due to the lake load, shoreline feature elevations reveal a statistically significant northward dipping trend. We attribute this trend to continent-scale deformation caused by the ice peripheral bulge of the Laurentide ice sheet, and take advantage of the position of these lakes on the distal flank of the peripheral bulge to provide new insights on mantle viscosity and Laurentide ice sheet reconstructions. We perform ice loading calculations to quantify the deformation of the solid Earth, gravity field, and rotation axis that is caused by the growth and demise of the Laurentide ice sheet. We test three different ice reconstructions paired with a suite of viscosity profiles and confirm that the revealed trend can be explained by deformation associated with the Laurentide ice sheet when low viscosities below the asthenosphere are adopted. We obtain best fits to shoreline data using ice models that do not have the majority of ice in the eastern sectors of the Laurentide ice sheet, with the caveat that this result can be affected by lateral variations in viscosity. We show that pluvial lakes in the western United States can place valuable constraints on the Laurentide ice sheet, the shape of its peripheral bulge, and the underlying mantle viscosity. Article in Journal/Newspaper Ice Sheet University of California: eScholarship Bonneville Lake ENVELOPE(-102.017,-102.017,56.083,56.083) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Lake Bonneville Lake Lahontan paleoshorelines glacial isostatic adjustment mantle viscosity Laurentide ice sheet Geochemistry & Geophysics Physical Sciences Earth Sciences |
spellingShingle |
Lake Bonneville Lake Lahontan paleoshorelines glacial isostatic adjustment mantle viscosity Laurentide ice sheet Geochemistry & Geophysics Physical Sciences Earth Sciences Austermann, J Chen, CY Lau, HCP Maloof, AC Latychev, K Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
topic_facet |
Lake Bonneville Lake Lahontan paleoshorelines glacial isostatic adjustment mantle viscosity Laurentide ice sheet Geochemistry & Geophysics Physical Sciences Earth Sciences |
description |
The deformation pattern of the paleoshorelines of extinct Lake Bonneville were among the first features to indicate that Earth's interior responds viscoelastically to changes in surface loads (Gilbert, 1885). Here we revisit and extend this classic study of isostatic rebound with updated lake chronologies for Lake Bonneville and Lake Lahontan as well as revised elevation datasets of shoreline features. The first order domal pattern in the shoreline elevations can be explained by rebound associated with the removal of the lake load. We employ an iterative scheme to calculate the viscoelastic lake rebound, which accounts for the deformation of the solid Earth and gravity field, to calculate a lake load that is consistent with the load-deformed paleotopography. We find that the domal deformation requires a regional Earth structure that exhibits a thin elastic thickness of the lithosphere (15–25 km) and low sublithospheric Maxwell viscosity (∼1019 Pa s). After correcting for rebound due to the lake load, shoreline feature elevations reveal a statistically significant northward dipping trend. We attribute this trend to continent-scale deformation caused by the ice peripheral bulge of the Laurentide ice sheet, and take advantage of the position of these lakes on the distal flank of the peripheral bulge to provide new insights on mantle viscosity and Laurentide ice sheet reconstructions. We perform ice loading calculations to quantify the deformation of the solid Earth, gravity field, and rotation axis that is caused by the growth and demise of the Laurentide ice sheet. We test three different ice reconstructions paired with a suite of viscosity profiles and confirm that the revealed trend can be explained by deformation associated with the Laurentide ice sheet when low viscosities below the asthenosphere are adopted. We obtain best fits to shoreline data using ice models that do not have the majority of ice in the eastern sectors of the Laurentide ice sheet, with the caveat that this result can be affected by lateral variations in viscosity. We show that pluvial lakes in the western United States can place valuable constraints on the Laurentide ice sheet, the shape of its peripheral bulge, and the underlying mantle viscosity. |
format |
Article in Journal/Newspaper |
author |
Austermann, J Chen, CY Lau, HCP Maloof, AC Latychev, K |
author_facet |
Austermann, J Chen, CY Lau, HCP Maloof, AC Latychev, K |
author_sort |
Austermann, J |
title |
Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
title_short |
Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
title_full |
Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
title_fullStr |
Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
title_full_unstemmed |
Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States |
title_sort |
constraints on mantle viscosity and laurentide ice sheet evolution from pluvial paleolake shorelines in the western united states |
publisher |
eScholarship, University of California |
publishDate |
2020 |
url |
https://escholarship.org/uc/item/5vn6d215 |
long_lat |
ENVELOPE(-102.017,-102.017,56.083,56.083) |
geographic |
Bonneville Lake |
geographic_facet |
Bonneville Lake |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
qt5vn6d215 https://escholarship.org/uc/item/5vn6d215 |
op_rights |
public |
_version_ |
1766030234979663872 |