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 95 for “"mid-ocean ridges"”.
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… of melting mafic lithologies to produce alkaline ocean-island basalts (OIB), an experimental study was carried out measuring clinopyroxene (Cpx)- melt and garnet (Gt)-melt partition coefficients during silica-poor garnet pyroxenite melting for a suite of trace elements, including U and Th, at …
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Mantle upwelling, melt generation, and magma transport beneath mid-ocean ridges
The formation of new oceanic crust is the result of a complex geodynamic system in which mantle rises beneath spreading centers and undergoes decompression melting. The melt segregates from the matrix and is focused to the rise axis, where it is eventually intruded and/or erupted to form the …
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Mantle upwelling, melt generation, and magma transport beneath mid-ocean ridges
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1997.
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… of melting mafic lithologies to produce alkaline ocean-island basalts (OIB), an experimental study was carried out measuring clinopyroxene (Cpx)melt and garnet (Gt)-melt partition coefficients during silica-poor garnet pyroxenite melting for a suite of trace elements, including U and Th, at 2.5GPa …
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A comparison of bistatic scattering from two geologically distinct mid-ocean ridges
… Institute of Technology, Dept. of Ocean Engineering, 1999.
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Crustal accretion and evolution at slow and ultra-slow spreading mid-ocean ridges
Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at slow-spreading centers by comparing axial crustal structure with that on conjugate …
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Crustal accretion and evolution at slow and ultra-slow spreading mid-ocean ridges
Half of the ocean crust is formed at spreading centers with total opening rates less than 40 km/Myr. The objective of this Thesis is to investigate temporal variations in active ridge processes and crustal aging at slow-spreading centers by comparing axial crustal structure with that on conjugate …
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Axial structure of fast spreading mid-ocean ridges : implications for overlapping spreading centers
Thesis (M.S.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1986.
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Mantle convection, melt migration and the generation of basalts at mid-ocean ridges
… and Planetary Sciences, and Woods Hole Oceanographic Institute, 1991.
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Interactions between mantle plumes and mid-ocean ridges : constraints from geophysics, geochemistry, and geodynamical modeling
This thesis studies interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR). Gravity data …
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The structure and thermal tectonics of planetary lithospheres : mid-ocean ridges and lunar impact basins
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985.
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Interactions between mantle plumes and mid-ocean ridges : constraints from geophysics, geochemistry, and geodynamical modeling
This thesis studies interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR). Gravity data …
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The response of two-phase hydrothermal systems to changing magmatic heat input at mid-ocean ridges
Hydrothermal processes at oceanic spreading centers are largely influenced by changing magmatic heat input. I use the FISHES code to investigate the evolution of surface temperature and salinity as a function of time-varying heat flux at the base of a two-phase, vapor-brine hydrothermal system. I …
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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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Structure and Accretion at Mid-Ocean Ridges With High Magma Supply: Perspectives From Seafloor Escarpments and Iceland
<p>Despite vast amounts of data about the ocean floor, very little is known about processes operating at mid-ocean ridge spreading centers and the generation of oceanic lithosphere that covers approximately 2/3 of Earth's surface. In particular, geologist are uncertain about specific details of …
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Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings
The structure of the oceanic lithosphere results from magmatic and extensional processes taking place at mid-ocean ridges (MORs). The temporal and spatial scales of the variability of these two processes control the degree of heterogeneity of the oceanic lithosphere, represented by two end-member …
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Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings
The structure of the oceanic lithosphere results from magmatic and extensional processes taking place at mid-ocean ridges (MORs). The temporal and spatial scales of the variability of these two processes control the degree of heterogeneity of the oceanic lithosphere, represented by two end-member …
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Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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Examining the effects of mid ocean ridge topography on 3D marine magnetometric resistivity model responses
… order to analyze and invert MMR data taken near Mid Ocean Ridges, it is important to understand the effects of ridge topography on MMR models. To analyze these effects a 3D MMR forward modeling program MMR3D_fwd is used to model Mid Ocean Ridges with varying slopes, resistivities, and …
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