Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events
Abstract. Ice-rafted debris in sediment cores from the North Atlantic suggests that the Laurentide ice sheet (LIS) periodically disgorged icebergs in brief but violent episodes which occurred approximately every 7,000 years. Here, I propose that Heinrich events (i.e., what these episodes are called)...
Main Author: | |
---|---|
Other Authors: | |
Format: | Text |
Language: | English |
Published: |
1993
|
Subjects: | |
Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.8268 http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf |
id |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.419.8268 |
---|---|
record_format |
openpolar |
spelling |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.419.8268 2023-05-15T13:34:16+02:00 Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events D. R. Macayeal The Pennsylvania State University CiteSeerX Archives 1993 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.8268 http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.8268 http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf text 1993 ftciteseerx 2016-01-08T03:54:19Z Abstract. Ice-rafted debris in sediment cores from the North Atlantic suggests that the Laurentide ice sheet (LIS) periodically disgorged icebergs in brief but violent episodes which occurred approximately every 7,000 years. Here, I propose that Heinrich events (i.e., what these episodes are called) were caused by free oscillations in the flow of the Laurentide ice sheet which arose because the floor of Hud-son Bay and Hudson Strait is covered with soft, unconsolidated sediment that forms a slippery lubricant when thawed. The proposed Heinrich event cycle has two phases. The growth phase occurs when the sediment is frozen and the LIS is stranded (immobile) on a rigid bed. The volume of the LIS slowly grows during this phase at a rate dictated by snow accumulation. The purge phase occurs when the basal sediment thaws and a basally lubricated discharge pathway (i.e., an ice stream such as those which occur in West Antarctica today) developes through Hudson Strait. The volume of the LIS rapidly equilibrates to the reduced basal friction during this phase by dumping icebergs into the Labrador Sea. The periodicity T-- n'/nr(-k Osl/2•) 2 • 7000 years of the proposed Heinrich event cycle is a func-tion of the thermal conductivity and diffusivity of ice, k and •c, respectively, the atmospheric sea level temperature Osl (in degrees Celsius), and the excess geothermal heat flux defined by •, = G- k F, where F is the atmospheric lapse rate, and G is the geothermal heat flux. Agreement between the predicted T and the apparent periodicity implied by the marine record is the main virtue of the free oscillation mechanism I propose. An alternative mechanism in which Heinrich events are forced by periodic variations in external climate is im- Text Antarc* Antarctica Hudson Strait Ice Sheet Labrador Sea North Atlantic West Antarctica Unknown Hudson Hudson Strait ENVELOPE(-70.000,-70.000,62.000,62.000) West Antarctica |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
ftciteseerx |
language |
English |
description |
Abstract. Ice-rafted debris in sediment cores from the North Atlantic suggests that the Laurentide ice sheet (LIS) periodically disgorged icebergs in brief but violent episodes which occurred approximately every 7,000 years. Here, I propose that Heinrich events (i.e., what these episodes are called) were caused by free oscillations in the flow of the Laurentide ice sheet which arose because the floor of Hud-son Bay and Hudson Strait is covered with soft, unconsolidated sediment that forms a slippery lubricant when thawed. The proposed Heinrich event cycle has two phases. The growth phase occurs when the sediment is frozen and the LIS is stranded (immobile) on a rigid bed. The volume of the LIS slowly grows during this phase at a rate dictated by snow accumulation. The purge phase occurs when the basal sediment thaws and a basally lubricated discharge pathway (i.e., an ice stream such as those which occur in West Antarctica today) developes through Hudson Strait. The volume of the LIS rapidly equilibrates to the reduced basal friction during this phase by dumping icebergs into the Labrador Sea. The periodicity T-- n'/nr(-k Osl/2•) 2 • 7000 years of the proposed Heinrich event cycle is a func-tion of the thermal conductivity and diffusivity of ice, k and •c, respectively, the atmospheric sea level temperature Osl (in degrees Celsius), and the excess geothermal heat flux defined by •, = G- k F, where F is the atmospheric lapse rate, and G is the geothermal heat flux. Agreement between the predicted T and the apparent periodicity implied by the marine record is the main virtue of the free oscillation mechanism I propose. An alternative mechanism in which Heinrich events are forced by periodic variations in external climate is im- |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
D. R. Macayeal |
spellingShingle |
D. R. Macayeal Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
author_facet |
D. R. Macayeal |
author_sort |
D. R. Macayeal |
title |
Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
title_short |
Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
title_full |
Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
title_fullStr |
Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
title_full_unstemmed |
Binge/purge oscillations of the Laurentide ice sheet as a cause of the North Atlantic Heinrich events |
title_sort |
binge/purge oscillations of the laurentide ice sheet as a cause of the north atlantic heinrich events |
publishDate |
1993 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.8268 http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf |
long_lat |
ENVELOPE(-70.000,-70.000,62.000,62.000) |
geographic |
Hudson Hudson Strait West Antarctica |
geographic_facet |
Hudson Hudson Strait West Antarctica |
genre |
Antarc* Antarctica Hudson Strait Ice Sheet Labrador Sea North Atlantic West Antarctica |
genre_facet |
Antarc* Antarctica Hudson Strait Ice Sheet Labrador Sea North Atlantic West Antarctica |
op_source |
http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.8268 http://www.seas.harvard.edu/climate/seminars/pdfs/MacAyeal_1993_Paleoceonography.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766051196112470016 |