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 21 for “"Submarine geology"”.
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Submarine geology of the Red Sea.
Massachusetts Institute of Technology. Dept. of Geology. Thesis. 1965. M.S.
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An outline of the inshore submarine geology of Southern South West Africa and Namaqualand
An outline of the inshore submarine geology of the south western coast of southern Africa is presented. The study is derived from diamond prospecting operations carried out between 1964 and 1970 in the shallow waters between Walvis Bay in South West Africa and the Olifants River mouth in …
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Absarokites from the Western Mexican Volcanic Belt : constraints on mantle wedge conditions
We have investigated the near liquidus phase relations of a primitive absarokite from the Mascota region in Western Mexico. Sample M.102 was chosen because it has high MgO contents, a high Mg# and F090 olivine phenocrysts, indicating it is primitive mantle melt. High-pressure experiments on a …
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Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity
Chapter 1 presents the first published measurements of Sr-isotope variability in olivine-hosted melt inclusions. Melt inclusions in just two Samoan basalt hand samples exhibit most of the total Sr-isotope variability observed in Samoan lavas. Chapter 3 deals with the largest possible scales of …
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Signatures of present and past melt distribution along fast and intermediate spreading centers
The work presented in this dissertation depicts past and present signatures of melt distribution at fast and intermediate spreading centers. The primary goal of the studies included in this thesis is to provide better understanding of melt distribution and variation in melt physical properties …
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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems
This thesis presents the results of four discrete investigations into processes governing the organic 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 …
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Analysis of stable sulfur isotopes and trace cobalt on sulfides from the TAG hydrothermal mound
Stable sulfur isotopes (δ34S) and trace Co are analyzed in sulfide and sulfate minerals from six sample types collected from the TAG active mound, 26°N Mid-Atlantic Ridge. δ34S values range from 2.7 to 2O.9%, with sulfate minerals isotopically indistinguishable from seawater (21%), and sulfide …
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Crustal structure of rifted and convergent margins : the U.S. East Coast and Aleutian margins
… which lie south of the currently active arc. The geology of the Bristol Bay region suggests that the crustal components here had an origin similar to that of the Alaska Peninsula margin- that is, accreted terranes. We find, however, that the crust beneath Bristol Bay has a typically continental …
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The isotope geochemistry of abyssal peridotites and related rocks
This dissertation studies several aspects of the formation of the Earth's oceanic mantle and crust, using a variety of geologic techniques, principally major elements, radiogenic isotopes and trace elements, but including petrography, mineral chemistry, x-ray diffraction, seafloor geomorphology, …
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The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers
Two-thirds of the surface of the Earth is created at mid-ocean ridges where magmas rise from the mantle and cool to form the oceanic crust. The objective of this Thesis is to examine the influence of magma supply and eruptive processes on axial morphology, crustal construction, and the properties …
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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
The radionuclides 231Pa and 230Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance …
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Mantle plume-midocean ridge interaction : geophysical observations and mantle dynamics
We analyze bathymetric and gravity anomalies at five plume-ridge systems to constrain crustal and mantle density structure at these prominent oceanic features. Numerical models are then used to explore the physical mechanisms controlling plume-ridge interaction and to place theoretical constraints …
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Detailed studies of the structure, tectonics, near bottom magnetic anomalies and microearthquake seismicity of the Mid-Atlantic Ridge near 37°N
The Mid-Atlantic Ridge is one of the most well known and yet poorly understood spreading centers in the world. A detailed investigation of the Mid-Atlantic Ridge crest near 37°N (FAMOUS) was conducted using a deeply towed instrument package. The objective was to study the detailed structure and …
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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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Ridge segmentation, tectonic evolution and rheology of slow-spreading oceanic crust
Two-thirds of the Earth's surface is oceanic crust formed by magmatic and tectonic processes along mid-ocean ridges. Slow-spreading ridges, such as the Mid-Atlantic Ridge, are discontinuous and composed of ridge segments. Segments are thus fundamental units of magmatic accretion and tectonic …
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The crustal structure and subsidence history of aseismic ridges and mid-plate island chains
This thesis consists of three papers examining problems related to the crustal structure, isostasy and subsidence history of aseismic ridges and mid-plate island chains. Analysis of gravity and bathymetry data across the Ninetyeast and eastern Walvis Ridges indicates these features are locally …
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Bottom currents and abyssal sedimentation processes south of Iceland
… are present in the axis of the major submarine canyon. ‘ Sandy contourite' deposits beneath the axis of the Iceland-Scotland Overflow Current are very poorly sorted muddy sands lacking primary sedimentary structures. Bioturbation is inferred to cause the unique characteristics of these …
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Evolution of oceanic gabbros : in-situ and ancient examples
This study is a geochemical investigation into the accretion of lower oceanic crust and processes of shallow melt-rock reaction at mid-ocean ridges. Major-, trace-elements, and isotopes from whole-rocks and minerals from the Lyngen Gabbro, a 480-My old dismembered ophiolite from the Scandinavian …
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