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 16 of 16 for “"Mantle xenoliths"”.
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S-wave velocity structure beneath the Kaapvaal Craton from surface-wave inversions compared with estimates from mantle xenoliths
… velocities estimated from approximately 100 mantle xenoliths brought to the surface in kimberlite pipes. As the xenoliths represent a snapshot of the mantle at the time of their eruption, comparison with recently recorded seismic data provides an opportunity to compare and contrast the …
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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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Halogen-element (F, Cl, and Br) behaviour in apatites, scapolite, and sodalite : an experimental investigation with field applications
… Oka carbonatite complex (Quebec), and Chinese mantle xenoliths and 36 scapolite samples from the Tieshan Fe-Cu skarn deposit (China), the Nickel Plate gold deposit (British Columbia), and the Grenville pegmatite/skarn/vein deposits (Ontario and Quebec) have been analyzed by electron microprobe …
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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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A comparison of the Nickel and the conventional geothermometers with respect to the Jagersfontein and the Matsoku kimberlite peridotite xenolits
… and geothermobarometrically well characterised mantle xenoliths from Matsoku and Jagersfontein by comparison to the more commonly used conventional geothermometers. The two published calibrations of the Ni geothermometer are in agreement to within ±500C in the temperature range of ~900°C to …
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The earth's interior from both a seismological and petrological perspective
… to estimate the amount and direction of upper-mantle anisotropy worldwide. One of the basic assumptions in making these measurements is that the anisotropy is confined to a single, homogeneous layer. In this thesis, I use both numerical and analytical modeling to examine the validity of this …
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Nominally volatile-free mantle minerals: a reservoir for water and fluorine in the Kaapvaal Craton
… 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. Full …
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The rheology and dynamics of the Precambrian lithosphere – insights from the British Isles
… Four, I compare the characteristics of the mantle on and off the microcraton using mantle xenoliths. I find that England and Wales are underlain by non-cratonic lithosphere that records a complex history of melting and metasomatic processes, confirming the untypical mode of formation of the …
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Characterization of pentlandite-bearing quartz veins of Kambalda, Western Australia
… such as layered mafic-ultramafic intrusions, mantle xenoliths and komatiite-associated magmatic sulfide deposits. Characterization of these quartz veins and understanding of timing and formation conditions have been determined through detailed optical petrography, scanning electron microscopy …
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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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Mantle conditions and kimberlite geochemical criteria controlling diamond survival in Kimberlites
… oxygen fugacity conditions in the Earth's deep mantle. However, during their residence in the mantle and transport to the surface by kimberlite magma, they may be exposed to deformation or oxidising conditions outside of their stability field, causing diamond corrosion and resorption processes. …
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Investigation of the upper mantle as a source for contribution to magnetic anomalies
… testing of the hypothesis that the lithospheric mantle contains significant magnetic regions that contribute to the magnetism observed/measured, either at or close to the Earth’s surface, or from satellite data. Chapter 1 “Eight good reasons why the mantle could be magnetic” (2014) published in …
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Magma genesis beneath active continental rifts
… with geophysical evidence for low-density mantle underlying both rifts, have traditionally been interpreted as evidence for anomalously hot mantle plumes actively rising from the deep mantle beneath both regions. However, in light of increasing evidence that these mantle structures may also …
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The carbon speciation in the Earth’s interior as function of pressure, temperature and oxygen fugacity
… the speciation of volatile elements both in the mantle and in mantle derived magmas. Carbon is one of the principal elements to be affected in this way because under reducing conditions it forms graphite or diamond, and under oxidizing conditions carbonate (or CO2-bearing) minerals and melts. The …
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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 …