Potential ice sheet and glacial modulation of volcanism in West Antarctica : constraints on the cadence of melt delivery into the crust
department or school: Science, Faculty of
department or school: Earth, Ocean and Atmospheric Sciences, Department of
data provider: DSpace
degree campus: UBCV
creator: Wanket, Sean
issued: 2024-04-18T21:09:27Z
issued: 2024
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: The rate of change of orbitally-driven variations in continental ice mass modulates volcanism by inducing variations in the compressional (lithostatic) stress regime of the wall rock surrounding hot magma reservoirs. At West Antarctica, as crustal temperatures rise in response to the delivery and storage of melt since 36 Ma, and to the insulating effects of a thick West Antarctic Ice Sheet emplaced ∼34 Ma, the effective viscosity of wall rocks decreases. Pressures in excess of lithostatic related to the injection of magma are increasingly relieved through wall rock creep at the expense of volcanism and stress changes imparted by orbitally-forced deglaciation are consequently reduced in magnitude and delayed in time. Theoretically, maximally rapid creep and a negligible volcanic response to orbital forcing corresponds to a time lag of 1/4 of the period of the glacial forcing. Clusters of tephra layers near Mount Berlin corresponding to peaks in the rate of change of volcanism occur at eight and 110 ka, but only the eight ka cluster lags a maximum in the rate of change of deglaciation by less than 1/4 of an obliquity-driven glacial cycle (∼6 kyr), suggesting the crust underwent a rheological transition before eight ka. Using a 1D numerical model of heat diffusion we study the effects of ice sheet insulation and time-dependent magma supply on the viscoelastic response of the crust to glacial cycles. Long-term ice insulation increases the crust’s proclivity for viscous creep by increasing the temperature by ∼50 K. However, a time-dependent magma supply causes the crust to alternately cool and warm. Through the exponential dependence of crustal viscosity on temperature, thermal oscillations and long-term insulation force the crust into transient behavior in which magma is preferentially stored during warmer intervals and erupted during cooler periods. We argue that the change in the response of the crust between 110 and eight ka is a consequence of such oscillations. Our…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/87880
note: Potential Ice Sheet and GlacialModulation of Volcanism in WestAntarcticaConstraints on the cadence of melt delivery into thecrustbySean WanketB.Sc., The University of British Columbia, 2020A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinThe Faculty of Graduate and Postdoctoral Studies(Geophysics)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)April 2024© Sean Wanket 2024The following individuals certify that they have read, and recommend tothe Faculty of Graduate and Postdoctoral Studies for acceptance, the thesisentitled:Potential Ice Sheet and Glacial Modulation of Volcanism in West Antarc-tica: Constraints on the cadence of melt delivery into the crustsubmitted by Sean Wanket in partial fulfillment of the requirements forthe degree of Master of Sciencein GeophysicsExamining Committee:Dr. A. Mark JellinekProfessor, Department of Earth, Ocean and Atmospheric Sciences, UBCCo-supervisorDr. Catherine JohnsonProfessor, Department of Earth, Ocean and Atmospheric Sciences, UBCCo-supervisorDr. Anais OrsiAssistant Professor, Department of Earth, Ocean and Atmospheric Sciences, UBCSupervisory Committee MemberDr. Jonathon FinkProfessor, Department of Geology, PSUAdjunct Professor, Department of Earth, Ocean and Atmospheric Sciences, UBCAdditional ExamineriiAbstractThe rate of change of orbitally-driven variations in continental ice massmodulates volcanism by inducing variations in the compressional (litho-static) stress regime of the wall rock surrounding hot magma reservoirs.At West Antarctica, as crustal temperatures rise in response to the deliveryand storage of melt since 36 Ma, and to the insulating effects of a thickWest Antarctic Ice Sheet emplaced ∼34 Ma, the effective viscosity of wallrocks decreases. Pressures in excess of lithostatic related to the injectionof magma are increasingly relieved through wall rock creep at the expenseof volcanism and stress changes imparted by orbitally-forced deglaciationare consequently r…
has type: Thesis/Dissertation
date issued: 2024-05
is shown at: 10.14288/1.0441414
language: eng
degree discipline: Geophysics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Jellinek, A. Mark
contributor: Johnson, Catherine
type: Text
identifier URI: http://hdl.handle.net/2429/87880