Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 149 for “"rifting"”.
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Incipient continental rifting: insights from the Okavango Rift Zone, northwestern Botswana
… insights into the early stages of continental rifting. The objectives of this study are (1) assessing the role of pre-existing structures on rift basin development, (2) characterizing the geometry of the nascent rift basins, (3) documenting fault growth and propagation patterns, and (4) …
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Effects of Initial Thermal Structure on the Evolution of Continental Rifting
Continental rifting is a fundamental earth process that displays a wide variety of styles ranging from narrow to wide, symmetric and asymmetric, magmatic and amagmatic. The key conditions and processes that control the evolution of rifts remain enigmatic. Previous research suggests that the initial …
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The 2014-15 Bárðarbunga-Holuhraun magmatic rifting episode: A seismic study
… collapse took place in the central volcano. The rifting episode was captured both geodetically and seismically. In this thesis, I analyse the seismic response to the event, both due to the dyke propagation, and the subsequent caldera collapse. This gives an insight into the underlying processes …
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Magmatism in southern Uruguay and the early rifting of the South Atlantic
… although rhyolite activity continued after rifting (127 - 126 Ma). The province therefore contains unique information about melting conditions at the periphery of the influence of the Tristan da Cunha plume. <br></br><br></br>The volcanic rocks of southern Uruguay are bimodal in silica, and …
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Dyke-induced earthquakes during the 2014-15 Bárðarbunga-Holuhraun rifting event, Iceland
… eruptions. The 2014-15 Bárðarbunga-Holuhraun rifting event comprised the best-monitored dyke intrusion to date and the largest eruption in Iceland in 230 years. Over a 13 day period magma propagated laterally from the subglacial Bárðarbunga volcano, Iceland, along a 48 km path before erupting …
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Seismic imaging and thermal modeling of active continental rifting processes in the Salton Trough, Southern California
Continental rifting ultimately creates a deep accommodation space for sediment. When a major river flows into a late-stage rift, thick deltaic sediment can change the thermal regime and alter the mechanisms of extension and continental breakup. The Salton Trough, the northernmost rift segment of …
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A Geodynamic Investigation of Continental Rifting and Mantle Rheology: Madagascar and East African Rift case studies
Continental rifting is an important geodynamic process during which the Earth's outer-most rigid shell undergoes continuous stretching resulting in continental break-up and theformation of new oceanic basins. The East African Rift System, which has two continentalsegments comprising largely of the …
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Evolution of oceanic margins : rifting in the Gulf of California and sediment diapirism and mantle hydration during subduction
… place new constraints on the history of early rifting there. Chapter 3 presents numerical experiments that show that diapirs can form in sediments on the down-going plate in subduction zones and rise into the mantle wedge, delivering the sedimentary component widely observed in arc magmas. …
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Tectonic and magmatic processes during extension in planetary lithospheres : rifting, spreading, delamination, and recycling on Earth and Venus
… controls the transition from continental rifting to seafloor spreading. The study finds that the transition is controlled by high temperature shear zones in the mantle and by a change in stress from gravitational collapse to buoyant upwelling of a melt-rich mantle. On Venus, extensional …
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Evolution of oceanic margins : rifting in the Gulf of California and sediment diapirism and mantle hydration during subduction
… place new constraints on the history of early rifting there. Chapter 3 presents numerical experiments that show that diapirs can form in sediments on the down-going plate in subduction zones and rise into the mantle wedge, delivering the sedimentary component widely observed in arc magmas. …
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A geological and geophysical study of the Tendaho Graben in the Afar Depression, Ethiopia: insights into transitional continental rifting
"A detailed magnetic and gravity study across the Tendaho Graben (the Red Sea propagator within the Afar Depression, Ethiopia) revealed features that can best be interpreted as a continental rift undergoing oceanization. This NW-trending extensional structure is ~50 km wide and it is confined …
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Tectonics of the lower Susquehhanna River region, southeastern Pennsylvania and northern Maryland: late proterozoic rifting to late paleozoic dextral transpression
… Creek deposits are also related to Iapetan rifting. Transpressional structural models have been applied to oblique convergence tectonics, with the coeval development of contractional and transcurrent structures. Late Paleozoic post-Taconian deformation in the north-central Appalachian …
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A Geodynamic Investigation of Magma-Poor Rifting Processes and Melt Generation: A Case Study of the Malawi Rift and Rungwe Volcanic Province, East Africa
… rift systems. To better understand magma-poor rifting processes, chapter 1 of this dissertation is focused on investigating the lithosphere-asthenosphere interactions beneath the Malawi Rift, a segment of the magma-poor Western Branch of the East African Rift (EAR). Chapter 2 and 3 are focused …
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Petrology and geochemistry of pyroxenites in the Lanzo ultramafic massif, Northwestern Italy
… and more generally on the role of magmatic rifting and the rift-to-drift transition in ultraslow-spreading ridge environments. Two separate generations of pyroxenites have been distinguished. A young set of primitive Cr-diopside websterites of MORB affinity are related to melt infiltrations …
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Modelling the controls on melt generation during continental extension and breakup
Rifting is the process that leads to the formation of oceans. Rifting is the break up of<br/>continents, leading to the formation of new oceanic floor between the two continental<br/>plates. Although the concept of continental rifting is accepted within the scientific<br/>community, it is still …
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Petrology and Diagenesis of Medium-Grained Clastic Sediments in the Back-Arc Basins of the Western Pacific Ocean (Japan, Daito)
… of the time of deposition with respect to rifting in the basin, I studied the petrology and diagenetic history of sandstones at seven DSDP sites (285, 286, 297, 299, 445, 446 and 453). These sites provided sandstones which had been deposited at various times with respect to the development …
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Tectonics of the West Iberia continental margin from seismic reflection data
Continental rifting is a fundamental component of the plate tectonic cycle. The West Iberia passive margin is a classic example of a nonvolcanic rifted margin. The West Iberia margin contains an enigmatic north-south ridge of serpentinized peridotite located within the ocean-continent transition. …
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Thermo-tectonic record of hyperextension, structural inversion, and foreland basin evolution of the eastern and central Pyrenees
Direct constraints on processes associated with rifting and mantle exhumation are necessary to understand the thermal and structural evolution of continental rift systems, and the role of pre-existing crustal architecture on orogenesis and foreland basin development. This work constrains the Early …
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