Tectonic Evolution of Oceanic Plateaus and Hotspot-Ridge Interactions: Walvis Ridge – Rio Grande Rise, South Atlantic and Tamu Massif, Pacific Ocean

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dc.contributor.advisorSager, William W.
dc.contributor.committeeMemberBird, Dale E.
dc.contributor.committeeMemberWu, Jonny
dc.contributor.committeeMemberTivey, Maurice A.
dc.creatorThoram, Sriharsha
dc.creator.orcid0000-0002-7240-5563
dc.date.accessioned2022-06-17T22:07:27Z
dc.date.createdDecember 2021
dc.date.issued2021-12
dc.date.submittedDecember 2021
dc.date.updated2022-06-17T22:07:28Z
dc.description.abstractOceanic plateaus are large basaltic provinces on the seafloor formed due to massive magma outpourings from an upwelling mantle. Many of these plateaus were formed at or near spreading ridges, suggesting that hotspot-ridge interaction was involved in their formation. However, the extent of ridge influence in their evolution remains unknown due to poor data coverage owing to their large size and remote locations. Magnetic anomaly patterns and geomorphology of these plateaus can provide important clues into their tectonic evolution. In this study, the tectonic evolution of three oceanic plateaus – Walvis Ridge (WR) and Rio Grande Rise (RGR) hotspot twins in South Atlantic Ocean and Shatsky Rise in Pacific Ocean – was investigated using magnetic, bathymetry, and seismic data. In the South Atlantic, a major reorganization of the Mid‐Atlantic Ridge (MAR) began before anomaly C34n (83.6 Ma) and ended before anomaly C30n (66.4 Ma), complicating the tectonics of RGR and older WR that formed together at the MAR. This reorganization is poorly understood because magnetic anomalies, C34n‐C30n, are poorly defined near WR and RGR. Chapter 2 presents an initial review of magnetic anomaly picks near WR and attempts to trace down missing anomalies. Subsequently, large amounts of magnetic data from WR and RGR were collected onboard research vessels Thomas G. Thompson (2019) and Nathaniel B. Palmer (2018). In Chapter 3, magnetic anomaly maps were generated for WR and RGR using all existing magnetic data and reconstructed to their past configurations to study the tectonic evolution of the plate reorganization. The anomaly patterns indicate that WR and RGR formed around a microplate between C34n-C33n, producing various edifices at or near a reorganizing ridge. In the northwest Pacific, a significant part of southern Shatsky Rise was mapped using multibeam sonar onboard R/V Falkor during a 2015 cruise. In Chapter 4, a new high-resolution bathymetry map of southern Shatsky Rise was generated and geomorphological implications of its tectonic and sedimentary evolution were studied in detail. The map reveals that the Tamu Massif is segmented, consisting of four smaller rises that suggest it formed by a series of ridge centered eruptions along a moving triple junction.
dc.description.departmentEarth and Atmospheric Sciences, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.citationPortions of this document appear in: Thoram, S., Sager, W. W., & Jokat, W. (2019). Implications of updated magnetic anomalies for the Late Cretaceous tectonic evolution of Walvis Ridge. Geophysical Research Letters, 46(16), 9474–9482.
dc.identifier.urihttps://hdl.handle.net/10657/9272
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectWalvis Ridge
dc.subjectRio Grande Rise
dc.subjectOceanic Plateaus
dc.subjectHotspot-Ridge Interactions
dc.subjectMagnetic Anomalies
dc.subjectBathymetry
dc.subjectTriple Junction
dc.subjectMicroplate
dc.subjectSecondary Volcanism
dc.titleTectonic Evolution of Oceanic Plateaus and Hotspot-Ridge Interactions: Walvis Ridge – Rio Grande Rise, South Atlantic and Tamu Massif, Pacific Ocean
dc.type.dcmiText
dc.type.genreThesis
dcterms.accessRightsThe full text of this item is not available at this time because the student has placed this item under an embargo for a period of time. The Libraries are not authorized to provide a copy of this work during the embargo period.
local.embargo.lift2023-12-01
local.embargo.terms2023-12-01
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.departmentEarth and Atmospheric Sciences, Department of
thesis.degree.disciplineGeophysics
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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