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 18 of 18 for “"oceanic spreading"”.
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The evolution of lithospheric deformation and crustal structure from continental margins to oceanic spreading centers
… bounds for the lower continental, margin, and oceanic crust.
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The evolution of lithospheric deformation and crustal structure from continental margins to oceanic spreading centers
This thesis investigates the evolution of lithospheric deformation and crustal structure from continental margins to mid-ocean ridges. The first part (Ch. 2) examines the style of segmentation along the U.S. East Coast Margin and investigates the relationship between incipient margin structure and …
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Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers
Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation …
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Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers
Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation …
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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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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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Metamorphism of the Troodos Massif, Cyprus
… Sequence, are comparable to those dredged from oceanic spreading axes, whereas the overlying rocks, the Upper Pillow Lavas, differ, and represent material erupted after the earlier metamorphic event. This group was subsequently metamorphosed in an environment with a lower the thermal gradient …
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The petrology, geochemistry and structure of the plutonic rocks of the Oman ophiolite
The Oman Ophiolite represents a fragment of oceanic crust and upper mantle that was emplaced onto the Arabian continental margin during the late Cretaceous. An area of 3000km2, comprising the Haylayn and Rustaq Blocks, has been mapped and specific localities were investigated in order to examine …
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Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea
… discovered vent fields at the ultra slow spreading Mid-Cayman Rise, Earth's deepest mid-ocean ridge. A wide variety of possible temperatures and substrates for fluid/rock reaction exist at ultraslow spreading ridges. The flux of chemicals delivered to the ocean by circulating vent fluids …
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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
… biological, and geological processes at oceanic spreading centers is important because these processes affect the global energy and biogeochemical budgets of the Earth system. Despite two decades of focused study of hydrothermal systems, several key questions remain concerning the …
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The Structural Evolution of the Faroe Islands, NE Atlantic Margin
… most likely continued through to the onset of oceanic-spreading on the Aegir ridge (ca. 55 Ma). Finally, (3) Event 1 and 2 structures were reactivated as extension and extensional-hybrid features, characterised best by the entrainment of clastic material along fault planes. Relative timings of …
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The role of long-term tectonic deformation on present day seismicity in the Caribbean and Central America
… setting comprised of transform zones, young oceanic spreading ridges, and subduction along its eastern and western boundaries. CCAR is, therefore, an ideal setting in which to study the impacts of long-term tectonic deformation on the distribution of present-day seismic activity. In this …
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The primary structures and fabrics of the upper mantle and lower oceanic crust from ophiolite complexes
… history of the upper mantle and lowermost oceanic crust at accretionary margins. In all areas the mantle has similar petrological features. It is composed largely of harzburgite which is often compositionally banded into orthopyroxene-rich and olivine-rich segregation layers. Dunitic sheets …
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QUASI STATIC GRAVITY SIGNATURES IN SLOW TECTONIC ZONES: ASSIMILATION OF NOVEL AEROSPACE DATA AND GEOPHYSICAL MODELING
… models, in which the formation of oceanic crust and serpentinite due to the hydration of upwelling mantle peridotite is implemented, to simulate the evolution of the Gulf of Aden from the rift initiation to the development of an active oceanic spreading center. The thermo-mechanical …
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The structure and seismicity of Icelandic rifts
… of the Earth’s crust has been built at oceanic spreading centres in the last 160 million years. To explore crustal extension processes and the architecture of these constructive plate boundaries I have studied the oceanic rift in Iceland. Here the Mid Atlantic Ridge is anomalously …
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Rare earth element systematics in ancient and modem hydrothermal systems
… associated with crustal generation at an oceanic spreading ridge. REE mobility was associated with the development of both high- (-200 to 350 C) and low temperature(<100 C) secondary phases which precipitated within contrasting alteration regimes (discharge- and recharge-dominated …
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Neotectonics & Cooling History of the Southern Patagonian Andes
The collision of bathymetric anomalies, such as oceanic spreading centers, at convergent plate margins can profoundly affect subduction dynamics, magmatism, and the structural and geomorphic evolution of the overriding plate. The Southern Patagonian Andes of South America are a prime example for …
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Variations in structure and tectonics along the Mid-Atlantic Ridge, 23⁰N and 26⁰N
… that the formation of ocean crust at slow spreading centers is not a simple two-dimensional process in which crustal accretion occurs uniformly both along the ridge axis and with time. Rather, it has been proposed that the ridge axis can be divided into a number of distinct segments or …