Insights from geodynamic models into ice flow, mantle magmatism, and their interactions
In this thesis, I use geodynamic models to study processes within the Earth's mantle and cryosphere. I begin by quantifying previously unconsidered sources of magmatic CO₂. In Chapter 2, I predict how small concentrations of CO₂ found in passively upwelling mantle throughout ocean basins may ge...
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Massachusetts Institute of Technology
2023
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ftmit:oai:dspace.mit.edu:1721.1/150070 2023-06-11T04:06:04+02:00 Insights from geodynamic models into ice flow, mantle magmatism, and their interactions Clerc, Fiona Behn, Mark D. Minchew, Brent M. Joint Program in Marine Geology and Geophysics Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences 2023-03-01T13:50:51.660Z application/pdf https://hdl.handle.net/1721.1/150070 unknown Massachusetts Institute of Technology https://hdl.handle.net/1721.1/150070 orcid:0000-0002-9857-6328 In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ Thesis 2023 ftmit 2023-05-29T08:19:13Z In this thesis, I use geodynamic models to study processes within the Earth's mantle and cryosphere. I begin by quantifying previously unconsidered sources of magmatic CO₂. In Chapter 2, I predict how small concentrations of CO₂ found in passively upwelling mantle throughout ocean basins may generate low-degree carbonate melting. I find the flux of CO₂ segregated by these melts rivals the flux from mid-ocean ridges. In Chapter 3, I model how the deglaciation of the Yellowstone ice cap caused a reduction in mantle pressures and enhanced melting 19-fold. I predict the additional melting segregates a globally-significant mass of CO₂, potentially playing a role in positive feedbacks between deglaciation and climate. I suggest enhanced melting may be important in other magmatically-active, continental settings undergoing rapid deglaciation -- for instance, under the collapse of the West Antarctic Ice Sheet (WAIS). This thesis next explores glaciological factors controlling WAIS stability, associated with the fracturing of ice sheet margins supported by floating ice shelves. The Marine Ice Cliff Instability posits ice cliffs above a critical height collapse under their own weight, initiating runaway ice sheet retreat. In Chapter 4, I model the formation of marine ice cliffs, as an Antarctic ice shelf is removed. I show that over ice-shelf collapse timescales longer than a few days (consistent with observations), ice cliffs comprised of intact ice are more stable, undergoing viscous flow rather than brittle fracture. I next investigate interactions between viscous and brittle processes, guided by observations on a modern Antarctic ice shelf. In Chapter 5, I model deformation at the McDonald Ice Rumples (MIR), formed as the Brunt Ice Shelf is grounded into a bathymetric high. The MIR are characterized by concentric folds intersected by radial fractures, implying viscous and brittle behavior, respectively. I interpret these features to constrain ice rheology and strength. More broadly, this final chapter highlights how ... Thesis Antarc* Antarctic Brunt Ice Shelf Ice cap Ice Sheet Ice Shelf Ice Shelves DSpace@MIT (Massachusetts Institute of Technology) Antarctic West Antarctic Ice Sheet Brunt Ice Shelf ENVELOPE(-22.500,-22.500,-74.750,-74.750) McDonald Ice Rumples ENVELOPE(-26.352,-26.352,-75.458,-75.458) |
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Open Polar |
collection |
DSpace@MIT (Massachusetts Institute of Technology) |
op_collection_id |
ftmit |
language |
unknown |
description |
In this thesis, I use geodynamic models to study processes within the Earth's mantle and cryosphere. I begin by quantifying previously unconsidered sources of magmatic CO₂. In Chapter 2, I predict how small concentrations of CO₂ found in passively upwelling mantle throughout ocean basins may generate low-degree carbonate melting. I find the flux of CO₂ segregated by these melts rivals the flux from mid-ocean ridges. In Chapter 3, I model how the deglaciation of the Yellowstone ice cap caused a reduction in mantle pressures and enhanced melting 19-fold. I predict the additional melting segregates a globally-significant mass of CO₂, potentially playing a role in positive feedbacks between deglaciation and climate. I suggest enhanced melting may be important in other magmatically-active, continental settings undergoing rapid deglaciation -- for instance, under the collapse of the West Antarctic Ice Sheet (WAIS). This thesis next explores glaciological factors controlling WAIS stability, associated with the fracturing of ice sheet margins supported by floating ice shelves. The Marine Ice Cliff Instability posits ice cliffs above a critical height collapse under their own weight, initiating runaway ice sheet retreat. In Chapter 4, I model the formation of marine ice cliffs, as an Antarctic ice shelf is removed. I show that over ice-shelf collapse timescales longer than a few days (consistent with observations), ice cliffs comprised of intact ice are more stable, undergoing viscous flow rather than brittle fracture. I next investigate interactions between viscous and brittle processes, guided by observations on a modern Antarctic ice shelf. In Chapter 5, I model deformation at the McDonald Ice Rumples (MIR), formed as the Brunt Ice Shelf is grounded into a bathymetric high. The MIR are characterized by concentric folds intersected by radial fractures, implying viscous and brittle behavior, respectively. I interpret these features to constrain ice rheology and strength. More broadly, this final chapter highlights how ... |
author2 |
Behn, Mark D. Minchew, Brent M. Joint Program in Marine Geology and Geophysics Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
format |
Thesis |
author |
Clerc, Fiona |
spellingShingle |
Clerc, Fiona Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
author_facet |
Clerc, Fiona |
author_sort |
Clerc, Fiona |
title |
Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
title_short |
Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
title_full |
Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
title_fullStr |
Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
title_full_unstemmed |
Insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
title_sort |
insights from geodynamic models into ice flow, mantle magmatism, and their interactions |
publisher |
Massachusetts Institute of Technology |
publishDate |
2023 |
url |
https://hdl.handle.net/1721.1/150070 |
long_lat |
ENVELOPE(-22.500,-22.500,-74.750,-74.750) ENVELOPE(-26.352,-26.352,-75.458,-75.458) |
geographic |
Antarctic West Antarctic Ice Sheet Brunt Ice Shelf McDonald Ice Rumples |
geographic_facet |
Antarctic West Antarctic Ice Sheet Brunt Ice Shelf McDonald Ice Rumples |
genre |
Antarc* Antarctic Brunt Ice Shelf Ice cap Ice Sheet Ice Shelf Ice Shelves |
genre_facet |
Antarc* Antarctic Brunt Ice Shelf Ice cap Ice Sheet Ice Shelf Ice Shelves |
op_relation |
https://hdl.handle.net/1721.1/150070 orcid:0000-0002-9857-6328 |
op_rights |
In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ |
_version_ |
1768377821468557312 |