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.
Results
Showing 1 to 20 of 39 for “"Mantle Melting"”.
-
Mantle-Melting at High Pressure: Experimental Constraints on Magma Ocean Differentiation
… likely existed during Earth’s accretion. The melting relations of potential magma ocean compositions, such as peridotitic and chondritic bulk compositions, were investigated using multianvil apparatus at pressures of 25-26 GPa and temperatures up to 2400°C. Compositional effects on the melting …
-
Mantle melting processes: evidences from ophiolites, large igneous provinces, and intraplate seamounts
Melting processes in the mantle have a key role in plate tectonics and in the most colossal phenomena in the Earth, like large igneous provinces, mantle plume upwellings, and the constant growth of the planet's tectonic plates. In this study we use the geochemical and petrological evidence …
-
Trace element geochemistry of oceanic peridotites and silicate melt inclusions : implications for mantle melting and ocean ridge magmagenesis
The mantle melting process is fundamental to basalt genesis and crustal accretion at mid-ocean ridges. It is believed that melts ascend more rapidly than the surrounding mantle, implying a process similar to fractional melting may be occurring, but geochemical evidence for this has been lacking. …
-
Trace element geochemistry of oceanic peridotites and silicate melt inclusions--implications for mantle melting and ocean ridge magmagenesis
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and Woods Hole Oceanographic Institution, 1990.
-
Effects of Glaciation on Volcanism in Iceland
… which increases the decompression rates in the mantle, causing enhanced mantle melting rates. However, existing theoretical work cannot account for large variations of Rare Earth Element (REE) concentrations in the Icelandic lavas. Lavas erupted during the last deglaciation are depleted in REEs …
-
The volcanology and petrogenesis of the Northern Lunar Crater Volcanic Field, Nye County, Nevada
… basalts formed by differing degrees of partial melting, independent of one another with no evidence for crustal contamination or commingling. A mantle melting column for the area indicates a deep (176 to 130 km) asthenospheric mantle source with temperatures 200°C hotter than average. This …
-
Magmatism and dynamics of continental breakup in the presence of a mantle plume
This thesis studies the dynamics of mantle melting during continental breakups by geophysical, geochemical, and numerical analyses. The first part focuses on the mantle melting and crustal accretion processes during the formation of the Southeast Greenland margin, on the basis of deep-crustal …
-
Magmatism and dynamics of continental breakup in the presence of a mantle plume
This thesis studies the dynamics of mantle melting during continental breakups by geophysical, geochemical, and numerical analyses. The first part focuses on the mantle melting and crustal accretion processes during the formation of the Southeast Greenland margin, on the basis of deep-crustal …
-
A heavy stable isotope approach to tracing mantle source and process
The geochemistry of global mantle melts suggests that both mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) sample lithological heterogeneities originating in both the upper and lower mantle, with recycled crustal material accounting for a significant part of this variability. …
-
INFERRED RHEOLOGY AND UPPER MANTLE CONDITIONS OF WESTERN NEVADA AND SOUTHERN CALIFORNIA-NORTHWEST MEXICO
… the viscous strength (rheology) of the mantle is essential for understanding the dynamics and evolution of the Earth. Rheology affects many geologic processes such as mantle convection, the earthquake cycle, and plate tectonics. This study uses tectonic (postseismic) and non-tectonic …
-
Seismic and gravitational studies of melting in the mantle's thermal boundary layers
… tools to the task of better understanding mantle melting phenomena at the upper and lower boundaries of the mantle. The first study uses seafloor bathymetry and small variations in the gravitational acceleration over the Hawaii-Emperor seamount chain to constrain the changes in the igneous …
-
Seismic and gravitational studies of melting in the mantle's thermal boundary layers
… tools to the task of better understanding mantle melting phenomena at the upper and lower boundaries of the mantle. The first study uses seafloor bathymetry and small variations in the gravitational acceleration over the Hawaii-Emperor seamount chain to constrain the changes in the igneous …
-
The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9º-25ºE) : basalt composition sensitivity to variations in source and process
… by long amagmatic accretionary segments, where mantle is emplaced directly to the seafloor with only scattered N-MORB and E-MORB erupted. Rather than a major break in mantle composition at the discontinuity between the supersegments, this sharp contrast in geometry, physiography, and chemistry …
-
The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
… investigated. Surprisingly, negative residual mantle Bouguer gravity anomalies are found within fastslipping transform fault domains. These gravity observations suggest a mass deficit within fast-slipping transform faults, which may result from porosity variations, mantle serpentinization, …
-
Differentiation in impact melt sheets as a mechanism to produce evolved magmas on Mars
<p>Asteroid bombardment contributed to extensive melting and resurfacing of ancient (> 3 Ga) Mars, thereby influencing the early evolution of the Martian crust. However, information about how impact melting has altered Mars’ crustal petrology is limited. Evidence from some of the largest impact …
-
The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
… investigated. Surprisingly, negative residual mantle Bouguer gravity anomalies are found within fast-slipping transform fault domains. These gravity observations suggest a mass deficit within fast-slipping transform faults, which may result from porosity variations, mantle serpentinization, …
-
Hydrous melt generation in the Earth's mantle
… of H₂O in the generation and modification of mantle melts at shallow pressures in subduction zones. In the first and second chapters, two experimental studies are presented that investigate direct mantle melting and then subsequent reaction of deeper mantle melts with overlying, cooler …
-
Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
To explore the ability 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, …
-
Geophysical and petrological constraints on ocean plate dynamics
… 2 and 3, I present the results from partial melting experiments of mantle peridotite that were conducted in order to examine the mantle melting point, or solidus, beneath a mid-ocean ridge. Chapter 2 determines the peridotite solidus at a single pressure of 1.5 GPa and concludes that the …
Page 1 of 2