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 12 of 12 for “"volcanic glass"”.
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Geothermal reservoir characterisation using automated mineralogy; implications for CO2 sequestration
… minerals, as well as amorphous material such as volcanic glass. Alongside the quantitative data, mineral maps were produced for each sample, showing the distribution of the different compositional groups which can be directly compared to the analysed thin sections. In addition the data is …
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Geology and petrology of the Devils Tower, Missouri Buttes, and Barlow Canyon area, Crook County, Wyoming
… alloclastic breccia with a crystal-charged volcanic glass matrix, surrounding depressions representing collapse of igneous material back into the vent, striking similarity to known volcante necks, and the occurrence of other extrusive volcan1S11\ in the vicinity lead to the conclusion that …
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Petrology of the Sentinel Butte Formation (Paleocene), North Dakota
… generally are classified mineralogically as volcanic litharenites or feldspathic litharenites. Most rock units in the formation are siltstones and mudstones. Multiple source rock types, including volcanic, metamorphic, and sedimentary, are represented by mineralogic constituents, but volcanic …
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Sub-surface geology, petrochemistry and hydrothermal alteration of Wells MW-03, MW-09 and MW-20 from Menengai geothermal field, Kenya
… Kenyan Rift Valley and covered by quarternary volcanics. The study wells, MW-03, MW-09 and MW-20, were drilled inside the Menengai caldera, which is characterized by ring faults, the Molo TVA which trends NNW-SSE and the Solai TVA which trends NNE-SSW direction. The volcano formed about 200,000 …
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The influence of structural relaxation upon the low-temperature thermal conductivity of ancient natural glasses
… low-temperature ( <lOK) properties of glasses depend upon a sample's thermal history. Apparently, the intrinsic glassy excitations (TLS) which dominate the low-temperature properties of glasses are affected by the structural relaxation which occurs in a glass sample in order to move …
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Rare earth element systematics in ancient and modem hydrothermal systems
… depleted in the light REEEu relative to pristine volcanic glass compositions. These data indicate that much of the REE signature of the alteration pipe is a post-mineralisation overprint acquired in the waning stages of hydrothermal activity and during the protracted alteration of the oceanic …
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Variability, origin and physical characteristics of dust aerosol in Iceland
… the world (Mongolia, Iran, USA, China). Frequent volcanic eruptions with the re-suspension of volcanic materials and dust haze increase the number of dust events fourfold, resulting in 135 dust days annually. The Sea Level Pressure oscillation controlled whether dust events occurred in NE or in …
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Carbon dynamics in restiad peatlands across different timescales
… are also known to contain phosphorus within the volcanic glass and the mineral apatite, both of which would be expected to weather and become biologically available due both to processes within the eruptive plume and within the bog post-deposition. As such we have found the restiad bogs studied …
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The role of wind and water in shaping earth's plateaus
… other environmental proxies, including hydrated volcanic glass shards from volcanic ashes intercalated in the sedimentary strata. There are few quantitative estimates of eolian bedrock-removal rates from arid, low relief landscapes. Wind-erosion rates from the western Qaidam Basin based on …
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Tephrostratigraphy, petrography, geochemistry, age and fossil record of the Ganigobis Shale Member and associated glaciomarine deposits of the Dwyka Group, Late Carboniferous, southern Africa
… as distal fallout ashes produced by explosive volcanic eruptions. The matrix consists of a micro- to cryptocrystalline clay mineral-quartz mixture. Rare fragments of splinter quartz, completely recrystallized ash-sized particles of former volcanic glass and few apatite and zircon grains are the …
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Nearshore and inner shelf sedimentation on the east Coromandel coast, New Zealand
… wide), and a local geology dominated by Tertiary volcanics covered by a thin veneer of more recent volcanic air fall deposits. It is also located on a lee shelf in a mid-latitude zone of dominant westerly winds, with these prevailing weather patterns disrupted by high speed east to northeasterly …
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Mountain-range uplift & climate-system interactions in the Southern Central Andes
Zwei häufig diskutierte Aspekte der spätkänozoischen Gebirgsbildung der Anden sind der Zeitpunkt sowie die Art und Weise der Heraushebung des Puna-Plateaus und seiner Randgebiete innerhalb der Ostkordillere und die damit verbundenen klimatischen Änderungen in NW Argentinien. Die Ostkordillere …