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 27 for “"hydrothermal circulation"”.
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Exploring two-phase hydrothermal circulation at a seafloor pressure of 25 MPa: Application for EPR 9°50′N
… simulations of two phase flow in seafloor hydrothermal systems using the finite control volume numerical scheme FISHES. The FISHES code solves the coupled non-linear equations for mass, momentum, energy, and salt conservation in a NaCl-H2O fluid to model the seafloor hydrothermal processes. …
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Hydrothermal alteration of the ocean crust: insights from Macquarie Island and drilled in situ ocean crust
Hydrothermal circulation is a fundamental process in the formation and aging of the ocean crust, influencing its structure, physical and chemical properties, and the composition of the oceans and the mantle. The impact of hydrothermal circulation on mid-ocean ridge processes depends on the …
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Geothermal heat flux from hydrothermal plumes on the Juan de Fuca ridge
Estimates of the heat output of hydrothermal vents, identified along the Endeavor and Southern Segments of the Juan de Fuca Ridge, are used to evaluate the total heat flux associated with hydrothermal circulation for the ridge segment. An array carried by D/V ALVIN sampled the temperature and …
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A Parameterized Approach to Partitioning Between Focused and Diffuse Heat Output and Modeling Hydrothermal Recharge at The East Pacific Rise 9°50´N
Ever since the discovery of seafloor hydrothermal systems at mid ocean ridges, scientists have been trying to understand the complex dynamic processes by which thermal energy is transported advectively by chemically reactive aqueous fluids from Earth's interior to the surface. Hydrothermal systems …
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Examining the effects of mid ocean ridge topography on 3D marine magnetometric resistivity model responses
… resistivity are uniquely suited to studying hydrothermal circulation in the crust. The magnetometric resistivity (MMR) technique is a galvanic method which uses a bipole current source with a magnetometer receiver. The resistivity of the subsurface can be estimated from the magnetic field …
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Examining the effects of mid ocean ridge topography on 3D marine magnetometric resistivity model responses
… resistivity are uniquely suited to studying hydrothermal circulation in the crust. The magnetometric resistivity (MMR) technique is a galvanic method which uses a bipole current source with a magnetometer receiver. The resistivity of the subsurface can be estimated from the magnetic field …
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Crustal accretion and evolution at slow and ultra-slow spreading mid-ocean ridges
… zone that is less than 5 km wide. Shallow-level hydrothermal circulation within the axial valley is suggested by the rift mountain seismic profiles, which show that the upper crust is 20% thinner and 16% faster along strike than zero-age crust. These effects probably result from fissure sealing …
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The accretion of lower oceanic crust
… of the plate tectonic cycle, and through hydrothermal interactions with seawater is a major control on the composition of the oceans, ocean crust, and upper mantle. Two complementary approaches are used to investigate the thermal implications of endmember theoretical models that describe …
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Surface-cycling of rhenium and its isotopes
… indicate that Re is essentially absent from the hydrothermal end member and Mo is present at concentrations considerably lower than ambient seawater. The sink fluxes represented by hydrothermal circulation are negligible in comparison to the revised river source fluxes. Anthropogenic …
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The geochemistry of methane isotopologues
… concept to constrain the origin of methane in hydrothermal fluids from sediment-poor vent fields hosted in mafic and ultramafic rocks on slow- and ultraslow-spreading mid-ocean ridges. The data support a hypogene model whereby methane forms abiotically within plutonic rocks of the oceanic crust …
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The geochemistry of methane isotopologues
… concept to constrain the origin of methane in hydrothermal fluids from sediment-poor vent fields hosted in mafic and ultramafic rocks on slow- and ultraslow-spreading mid-ocean ridges. The data support a hypogene model whereby methane forms abiotically within plutonic rocks of the oceanic crust …
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Exploring the relationship between crustal permeability and hydrothermal venting at mid-ocean ridges using numerical models
Hydrothermal systems associated with oceanic spreading centers account for a quarter of Earth's total heat flux and one third of the heat flux through the ocean floor. Circulation of seawater through these systems alters both the crust and the circulating fluid, impacting global geochemical cycles. …
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A study of the seismic structure of upper oceanic crust using wide-angle reflections
… in upper Layer 2 caused by faulting, hydrothermal circulation etc. The data employed are a set of wide-angle reflections from oceanic crust 130 m.y. old in the western North Atlantic Ocean southwest of Bermuda. First, the sedimentary structure is determined by stacking the data along …
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An analysis of the morphology and volcano-tectonic structure of the Central Indian Ridge between 18º and 21ºS
… permeability and a greater potential for hosting hydrothermal circulation. Analysis of geochemical data along the CIR identifies five hydrothermal plume signatures, three of which are coincident with the locations of NTDs in the study area, correlating with the findings of the numerical analysis. …
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Surface-cycling of rhenium and its isotopes
… indicate that Re is essentially absent from the hydrothermal end member and Mo is present at concentrations considerably lower than ambient seawater. The sink fluxes represented by hydrothermal circulation are negligible in comparison to the revised river source fluxes. Anthropogenic …
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Deciphering the signature of fluid/rock reactions in the lower oceanic crust: The Oman ophiolite analogue
Hydrothermal circulation is a key Earth process, moderating elemental and heat transfers between oceanic lithosphere and the hydrosphere. The characterization and quantification of fluid/rock reactions and fluid fluxes in fast-spreading mid-ocean ridges has been a long-term ambition given these …
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Hydrothermal Transport in the Panama Basin and in Brothers Volcano using Heat Flow, Scientific Deep Sea Drilling and Mathematical Models
… revealed along intraoceanic arcs and seamounts. Hydrothermal systems and the circulation patterns associated with these volcanic settings remove heat from the solid Earth into the deep ocean. Hydrothermal circulation continues to remove and redistribute heat in the crust as it ages. The heat and …
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The production and fate of nitrogen species in deep-sea hydrothermal environments
Nitrogen (N) species in hydrothermal vent fluids serve as both a nutrient and energy source for the chemosynthetic ecosystems surrounding deep-sea vents. While numerous pathways have been identified in which N-species can be produced and consumed in the context of submarine hydrothermal vent …
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Hydrothermal alteration of upper oceanic crust formed at fast spreading rates
Hydrothermal circulation plays a fundamental role in the chemical transfer from deep in the Earth’s interior to the ocean crust, the oceans and the atmosphere. It is also on of the principal mechanisms for heat transfer from the mantle to the oceans, atmosphere and ultimately, outer space. This …
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
… and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting …
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