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 23 for “"Subducting slab"”.
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Compressible Convection and Subduction: Kinematic and Dynamic Modeling
… is evaluated by using kinematically prescribed slab and steady-state models. The effect of compressibility is primarily expressed as an additional heat source created by viscous dissipation. The heat results in thinner thermal boundary layer on the subducting slab and increases slab …
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The effects of viscous stressed and mantle velocities on subduction : finite difference modeling
… model focuses on how the angle, a, at which the slab subducts and the rate, Vr , at which the subduction boundary "retreats" are affected by the negative buoyancy of the subducting lithospheric slab and the viscous forces that arise where the mantle and subducting slab are in motion relative to …
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Applying Garnet and Zircon REE Linkages to Determine Timing of P-T Conditions and Tectonic Implications for UHP Eclogites and HP Granulites, Dulan UHP Terrane, China
… that the HP granulite originated from the subducting slab, not the upper plate as previously proposed, as it is unlikely the upper plate was >80 km thick. Combining results from both the HP granulite and UHP eclogite suggests that these two rock types record processes near the top of the …
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Seismic studies of subducted lithosphere
… My results show that the configuration of the subducting slab and the state of strain within the subducted lithosphere are highly variable along both the strike and dip. In particular, I observed down-dip compressional strain in the northern and central portions of the arc between depths of 200 …
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The Relationship Between Intraplate Earthquakes and Temperature
… of the lithosphere in continental areas and subducting slabs. In these settings, the relationship between temperature and the distribution of seismicity, particularly in the mantle, is examined. The dissertation is divided into three studies, which are largely self-contained and deal with …
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Anisotropy and deformation in the Earth's mantle : seismological observations, geodynamical models, and laboratory experiments
… anisotropy in the mantle wedge above the subducting slab. I consider several scenarios that would produce the observed anisotropy and conclude that the most likely model for deformation beneath the Ryukyu arc is corner flow in the mantle wedge, with a region extending ~ 150 kilometers from …
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Seismic Studies of Subducted Lithosphere Beneath Fiji: Evidence for a Petrologic Anomaly
… Tonga subduction zone where cold lithosphere is subducting rapidly at 200 mn/yr. Under these conditions, the lack of prominent anomalies of high VP and VS in the lower mantle implies that a large amount of recently subducted material remains above the lower mantle. This inference is also evident …
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Applications of Melt Inclusions to Problems in Igneous Petrogenesis
… and still retain a T-MORB signature from the subducting slab.
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Geochemical fractionation during melting of sulfide and sulfate bearing mantle lithologies
… of the subducted sulfur gets released from the subducting slab to the surrounding mantle at sub-arc depths while the rest continues deeper and gets recycled into the mantle. As S is a multi-valent element with high redox potential, presence of different S species in a system will help us discern …
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Volatile chemistry, and nitrogen sources and fluxes, in subduction zones : insights from the Izu-Bonin-Mariana Arc
… of parameters, including sediment composition, slab dip and slab age, vary systematically along strike of the arc. Volcanic emissions are typical of convergent margin volcanoes, and are dominated by H2O, CO2 and S species. Most samples have high N2/He and low CO2/N2,exc., due to addition of …
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Fluid-mobile element cycling (halogens, boron, lithium) and sourcing through the Costa Rican convergent margin
… the forearc. Describing fluid loss from subducting oceanic crust to the forearc is difficult for several reasons including differences in pathways due to faulting, variability in the depth in which fluids are released, and compositional changes of the subducting slab. Seepage through the …
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Lithium, Beryllium and Boron in High-Pressure Metamorphic Rocks from Syros (Greece)
… light elements in different lithologies within subducting slabs, and they are essential for modelling of trace-element and isotope fractionation during subduction and dehydration of oceanic crust. In addition, the hosts of Li, Be and B were quantified with respect to the whole rock budgets. …
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The roof of the cyclades : a structural, stratigraphic, and paleomagnetic study of Neogene extensional tectonics in Central Greece
… largely governed by the dynamics of a retreating subducting slab. I document a newly-described low-angle normal fault, termed the Octonii Detachment, that accommodated NE-SW directed crustal extension and controlled the pattern of sedimentation within the Early to Middle Miocene Kymi-Aliveri …
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Seismic discontinuities and order estimation using wavelets : a receiver function approach
… are each thought to be underlain by a single subducting slab. JIZ, SGN, and TYM are located in central Japan where the Pacific and Philippine plates meet, and the subduction zone is thought to be very complex, with 2 slabs intersecting directly below these stations. Order and scale estimates …
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Investigation of the upper mantle as a source for contribution to magnetic anomalies
… and thus supports that stepwise dehydration of a subducting slab may produce positive and negative anomalies in the mantle wedge. As first author I prepared samples, ran experiments, processed data, produced figures, wrote the manuscript and applied for funding.</p>
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Experimental investigation of the fluid driven carbonation of serpentinites and spinel-peridotites: implications for the carbon and trace element cycle in the forearc region of the mantle wedge
… amounts of carbon (C) are released from the subducting slab into fluids, but less carbon is outgassed in arc volcanoes implying the storage of C in the mantle wedge. This experimental study investigates the fate of C bearing aqueous fluids when they travel through the (partially) hydrated …
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Experimental investigation of the fluid driven carbonation of serpentinites and spinel-peridotites: implications for the carbon and trace element cycle in the forearc region of the mantle wedge
… amounts of carbon (C) are released from the subducting slab into fluids, but less carbon is outgassed in arc volcanoes implying the storage of C in the mantle wedge. This experimental study investigates the fate of C bearing aqueous fluids when they travel through the (partially) hydrated …
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Towards a model of the Cenozoic tectonic development of New Zealand
… displacement through New Zealand. (5) The subducting slab of Pacific Ocean lithosphere progressively increased its extent to the southwest beneath northern New Zealand and concomitantly increased its dip. Based on these solutions, it is proposed that the Cenozoic geological development of …
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Halogens and trace elements in subduction zones
… peridotite mineral assemblage, fluid flow from a subducting slab through the mantle wedge will lead to more efficient sequestration of H2O (when compared to Cl) into minerals, thus inducing a gradual increase in the fluid salinity. Mass balance calculations reveal that rock-fluid ratios of …
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Different styles of deformation of the fore-arc wedge along the Chilean convergent margin : insights from 3D numerical experiments
… of the two Chilean study areas, such as the slab dip and the thickness of the continental crust, the downdip limit of the southern study area is slightly shallower than that of the northern study area. The results of the 2D thermal models are used to constrain the spatial extent of the …
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