The Signatures of and Feedbacks between Magmatic and Surface Processes in Volcanic Provinces
| dc.contributor.advisor | Karlstrom, Leif | |
| dc.contributor.author | O'Hara, Daniel | |
| dc.date.accessioned | 2021-04-27T20:43:56Z | |
| dc.date.available | 2021-04-27T20:43:56Z | |
| dc.date.issued | 2021-04-27 | |
| dc.description.abstract | In this dissertation, I analyze the relationship between magmatic structures in the upper- to mid-crust and overlying surface topography. Beginning with a theoretical approach, I examine the impact of localized uplift perturbations associated with shallow magmatic intrusions on regional-scale landscape evolution. I find that landscape response varies from simple knickpoint generation to regional river channel reorganization and drainage divide migration. Furthermore, I determine a series of nondimensional numbers that predict transient topographic evolution. Afterwards, I expand on this framework to explore the topographic signatures of regional and long timescale crustal magmatism. Starting from an elastic deformation model of a single intrusion, I simulate the topographic impact of many stochastically-emplaced intrusions. I find that intrusion spatial distribution controls the topographic expression of magmatism and the degree of crustal thickening versus topography generation. Furthermore, I parameterize these results using a thin-plate flexure model, showing that shallower and larger intrusions cause higher surface relief consistent with an effective plate thickness that scales with mean intrusion depth. In the final chapter, I move from theory to observations and analyze the correspondence between surface and subsurface signatures of magmatism in the Cascades Arc (northwestern U.S.) by combining geological and geophysical data. Using a recently-published database of volcanic vents that erupted during the Quaternary, I derive volume estimates for 2835 edifices, and find that these volumes correspond to ~50% of total extruded volumes within the Cascades over the last 2.6 Myr. Afterwards, I analyze the correlation between edifice volumes, vent spatial distributions, and geophysical datasets that constrain shallow- to mid-crustal structures. I find that both the number and magnitude of correlations increase when datasets are interpolated to volcanic vents. Furthermore, correlation magnitudes are highest with the most-recently active vents, and decrease through time, suggesting transient evolution of crustal magmatic structure over the last 2.6 Myr. Together, these chapters provide new insight into the ability to characterize crustal magmatic systems from topographic form and response, and are broadly applicable to volcanic provinces both on Earth and other planetary bodies. | en_US |
| dc.identifier.uri | https://hdl.handle.net/1794/26182 | |
| dc.language.iso | en_US | |
| dc.publisher | University of Oregon | |
| dc.rights | All Rights Reserved. | |
| dc.subject | Cascades Arc | en_US |
| dc.subject | Crustal Magmatism | en_US |
| dc.subject | Landscape Evolution | en_US |
| dc.subject | Volcanic Geomorphology | en_US |
| dc.title | The Signatures of and Feedbacks between Magmatic and Surface Processes in Volcanic Provinces | |
| dc.type | Electronic Thesis or Dissertation | |
| thesis.degree.discipline | Department of Geological Sciences | |
| thesis.degree.grantor | University of Oregon | |
| thesis.degree.level | doctoral | |
| thesis.degree.name | Ph.D. |
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