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 51 for “"Lithospheric Mantle"”.
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Cratonic eclogite xenoliths - formation and evolution of the subcontinental lithospheric mantle
… hard to evaluate, except through the study of mantle xenoliths brought to the surface by kimberlite magmas. Most mantle xenoliths undergo kimberlitic/carbonaceous metasomatism prior to their entrapment, altering their primary composition. Despite a very complex history and a very low abundance …
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Survival of Brown Colour in Diamond During Storage in the Subcontinental Lithospheric Mantle
… deformation during storage in the subcontinental lithospheric mantle (SCLM). Dislocation movement generates vacancies, which aggregate into clusters of perhaps 30–60 vacancies. Positron annihilation lifetime spectroscopy (PALS) and electron energy loss spectroscopy (EELS) support such vacancy …
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The composition of noble gas and co2 in the european subcontinental lithospheric mantle
… in fluid inclusions (FI) from selected mantle xenoliths erupted in Europe during alkaline magmatism. The aim of the thesis is to show how the occurrence of partial melting, metasomatism, refertilization, magmatic degassing, volatile recycling, and mixing of volatiles modified the …
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The density and evolution of sub-cratonic lithospheric mantle constrained by geological and geophysical observations
This Dissertation was approved for publication on 2022-04-20 at 20:57.
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The nature and co-behaviour of volatile and non-volatile elements in the sub-continental lithospheric mantle
The lithospheric mantle represents a critical interface in global volatile cycles because it separates Earth’s convecting mantle from the rigid crust. Nevertheless, the source, abundance and flux of volatiles stored in this reservoir are poorly constrained. In this work, the concentrations of …
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Nominally volatile-free mantle minerals: a reservoir for water and fluorine in the Kaapvaal Craton
The extent to which Earth’s sub-cratonic lithospheric mantle acts as a major repository for volatile elements is poorly constrained. This study presents the first systematic investigation into water, fluorine and chlorine storage in nominally volatile-free mantle minerals from sub-cratonic mantle. …
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Teleseismic imaging of the Slave craton and implications for the assembly of cratonic lithosphere
… complementary seismological methods to image the lithospheric structure of the Slave craton in Canada. First, I perform surface wave tomographic inversions to constrain the depth dependence of Rayleigh wave phase velocity, shear wave velocity, and azimuthal anisotropy of the Slave cratonic …
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A comparison of melt depletion, thermal structure and metasomatism of proterozoic mantle lithosphere in the Namaqua-Natal and Rehoboth Provinces of Southern Africa
… of melt extraction and metasomatism of the two mantle terranes with each other and with the Archaean Kaapvaal craton. Xenoliths from the Rietfontein and Pofadder localities have never previously been studied in detail. The information from this study is crucial for understanding the thermal and …
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Some studies on the computation and interpretation of seismic interface waves and modes in Earth’s mantle
… focusing on interface waves and modes in Earth’s mantle. The thesis consists of two parts. In the first part, I characterise the lithospheric mantle in southwestern Tibet, based on Rayleigh wave dispersion, receiver functions, and virtual deep seismic sounding profiles. These observations indicate …
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Isotopic, geochemical, and geochronological constraints on the origin and evolution of Cenozoic volcanism, Baikal Rift Zone, Siberia
… to Recent age volcanic rocks and associated mantle xenoliths are distributed in three major regions of the rift zone: the Udokan volcanic field in the northeast, the Vitim volcanic field -200 km southeast of Lake Baikal, and a broad zone of volcanism to the southwest of Lake Baikal. This …
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Geochemical, Isotopic, and Mineralogical Characterization of the Frobisher Suite Mafic-Ultramafic Sills, Southern Baffin Island, Nunavut, with Implications for Metallogenic Potential
… melting occurred to differing degrees within a mantle plume head, at various depths below the Meta Incognita microcontinent at ca. 1900 Ma. A number of sills formed via injections of multiple, distinct magma types, some of which were influenced by subcontinent lithospheric mantle. Disseminated …
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Petrogenesis of the phase 1 gabbro-diorite of the Miocene Mt Perkins Pluton, northwest Arizona: Implications for the role of mantle-derived mafic magmas in calc-alkaline magma evolution
… fractional crystallization of an asthenospheric mantle derived mafic magma and magma mixing with an upper crustal granitic magma. Phase 1 magmas evolved by fractional crystallization (required by the presence of cumulates) of an asthenospheric mantle derived mafic magma and contamination by an …
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Micro-geochemistry of the mantle and its volcanic rocks
… of deeply derived kimberlite melts to lithospheric processes. To be able to make these links it is necessary to better constrain the geochemical composition of the primary kimberlite melt. • The first study investigates inter-grain trace element and Sr isotope variation in clinopyroxene …
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Classification and petrogenesis of the Tongo dike-01 from the Tongo-Tongoma cluster, Sierra Leone: constraints from bulk rock geochemistry
… the world derive from the same asthenospheric mantle reservoir and their major element chemistry is controlled by the compositions/mineralogy of the lithospheric mantle assimilated during kimberlite evolution. The similarity of the trace element ratios and Sr-Nd-Pb isotopes of the Tongo dike-01 …
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Tectonic implications of mantle source changes recorded by Eocene-Oligocene basalts from the Dillon volcanic field southwest Montana (USA)
… Farallon slab rollback, slab tearing/foundering, lithospheric drip), which erupted during the later period of regional extension and basin sedimentation. Dillon volcanic rocks have mainly high-K compositions, are primarily subalkaline, but include eruptions of small volume alkali basalts. The …
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Cenozoic potassic magmatism and uplift of the Western United States
… Sierra Nevada, represent primary or near primary mantle-derived melts that have experienced limited crystal fractionation and/or crustal contamination. Yet despite this each suite of samples is characterised by a significant range of trace element and isotope ratios. The variation in LIL/HFS …
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Kimberlites, megacrysts and related xenocrysts from southern and Central Africa: geochemistry and petrology
… the evolution of the subcontinental lithospheric mantle (SCLM) beneath the northeastern Kasai Craton and the petrogenesis and sources of central African kimberlites. The geochemistry of southern and central African megacryst suites is generally consistent with their derivation from …
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Geochemical and rheological constraints on the dynamics of the oceanic upper mantle
I provide constraints on mantle convection through observations of the rheology and composition of the oceanic upper mantle. Convection cannot be directly observed, yet is a fundamental part of the plate tectonic cycle. Relative motion among plates is accommodated by localized deformation at their …
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Geochemical and rheological constraints on the dynamics of the oceanic upper mantle
I provide constraints on mantle convection through observations of the rheology and composition of the oceanic upper mantle. Convection cannot be directly observed, yet is a fundamental part of the plate tectonic cycle. Relative motion among plates is accommodated by localized deformation at their …
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Seismic Studies of the Mantle Transition Zone
… show that due to high VP near the bottom of the mantle transition zone, the contrast in VP across the 660-km discontinuity beneath central Tibet is small (around 3.1%): only about 70% of that beneath the northern Indian shield. This sub-horizontal anomaly of high V P is most likely a remnant of …
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