Evolution of Glacially Derived Freshwater and Overpressure in the Massachusetts Shelf: An Integration of Geophysical and Numerical Methods

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dc.contributor.advisorDugan, Brandonen_US
dc.contributor.committeeMemberGonnermann, Helge M.en_US
dc.contributor.committeeMemberAnderson, John B.en_US
dc.contributor.committeeMemberBedient, Philip B.en_US
dc.creatorSiegel, Jacoben_US
dc.date.accessioned2014-10-10T21:37:33Zen_US
dc.date.available2014-10-10T21:37:33Zen_US
dc.date.created2013-12en_US
dc.date.issued2013-10-24en_US
dc.date.submittedDecember 2013en_US
dc.date.updated2014-10-10T21:37:34Zen_US
dc.description.abstractThe continental shelf offshore Massachusetts, USA experienced repeated glaciations throughout the late Pleistocene that emplaced freshwater and generated overpressure in the shelf sediments that still remains offshore. To show this, I processed and interpreted high-resolution, multi-channel seismic data that was collected offshore Massachusetts to infer the glacial history and to incorporate the glacial history into numerical modeling. Interpretations of the seismic data reveal the shelf stratigraphy and the location of a late Pleistocene (Marine Oxygen Isotope Stage 12) ice sheet. The ice sheet extended 100 km farther onto the shelf compared to the Laurentide ice sheet during the Last Glacial Maximum (LGM). It also contained an ice stream that was likely sourced from the Gulf of Maine. I show that the late Pleistocene ice sheet influenced the shelf hydrogeology by generating overpressure and emplacing freshwater into the shelf sediments. Overpressure is modeled in 1D from high-resolution, full-waveform inversion p-wave velocities obtained from the seismic data and from a finite-difference fluid flow model that accounts for sedimentation and ice sheet loading. The results demonstrate how loading from the late Pleistocene ice sheet caused focused fluid flow that created localized zones of overpressure nearly 1-2 MPa in offshore sediments. Freshwater emplacement into shelf sediments is estimated with a finite-element, variable-density model of fluid flow and heat and solute transport that accounts for ice-sheet loading and sea-level change. The model helps explain how the late Pleistocene ice sheet emplaced nearly 100 km3 of freshwater into the sediments. Our results thus integrate seismic interpretations of ice sheet history with numerical techniques of fluid flow modeling to show how the past glacial history influenced the present freshwater distribution.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationSiegel, Jacob. "Evolution of Glacially Derived Freshwater and Overpressure in the Massachusetts Shelf: An Integration of Geophysical and Numerical Methods." (2013) Diss., Rice University. <a href="https://hdl.handle.net/1911/77523">https://hdl.handle.net/1911/77523</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/77523en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectGeophysicsen_US
dc.subjectHydrogeologyen_US
dc.subjectPleistoceneen_US
dc.subjectGlaciationsen_US
dc.titleEvolution of Glacially Derived Freshwater and Overpressure in the Massachusetts Shelf: An Integration of Geophysical and Numerical Methodsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentEarth Scienceen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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