Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor : Peter H. Schultz. Includes bibliographical references.

Thesis (Ph. D.). / Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--San Diego State University, 1974. / Three maps on 3 folded leaves in pocket. Includes bibliographical references (leaves [118]-123).

Lakes sediments from the Lofoten Islands, Norway, can be used to generate well resolved records of past climate and environmental change. This dissertation presents three lacustrine paleoenvironmental reconstructions that show evidence for Holocene climate changes associated with North Atlantic climate dynamics and relative sea-level variations driven by glacio-isostatic adjustment. This study also uses distal tephra deposits (cryptotephra) from Icelandic volcanic eruptions to improve the chronologies of these reconstructions and explores new approaches to crypto-tephrochronology. Past and present conditions at Vikjordvatnet, Fiskebølvatnet, and Heimerdalsvatnet were studied during four field seasons conducted from 2007–2010. Initially, each lake was characterized by measuring water column chemistry, logging annual temperature fluctuations, and conducting bathymetric and seismic surveys. Sediment cores were then collected and analyzed using multiple techniques, including: sediment density, magnetic susceptibility, loss-on-ignition, total carbon and nitrogen, δ13C and δ 15N of organic matter, and elemental compositions acquired by scanning X-ray fluorescence. Chronologies were established using radiocarbon dating and tephrochronology. A 13.8 cal ka BP record from Vikjordvatnet provides evidence for glacial activity during the Younger Dryas cold interval and exhibits trends in Ti, Fe, and organic content during the Holocene that correlate with regional millennial-scale climate trends and provide evidence for more rapid events. A 9.7 cal ka BP record from Fiskebølvatnet shows a strong signal of sediment inwashing likely driven by local geomorphic conditions, although there is evidence that increased inwashing at the onset of the Neoglacial could have been associated with increased precipitation. Heimerdalsvatnet provides a record of relative sea-level change. A 7.8 cal ka BP sedimentary record reflects changes in salinity and water column conditions as the lake was isolated and defines sea-level regression following the Tapes transgression. Cryptotephra horizons were identified in sediments of Heimerdalsvatnet, Vikjordvatnet, and Sverigedalsvatn. They were also found in a Viking-age boathouse excavated along the shore of Inner Borgpollen. These include the GA4-85, BIP-24a, SILK-N2, Askja, 860 Layer B, Hekla 1158, Hekla 1104, Vedde Ash, and Saksunarvatn tephra. This research project also explored the use of scanning XRF to locate cryptotephra in lacustrine sediments and presents experimental results of XRF scans of tephra-spiked synthetic sediment cores.

Two lakes were studied in detail for rock magnetic properties: Lake El'gygytgyn, a crater lake formed 3.6Ma in the Far Eastern Russian Arctic, and Heimerdalsvatnet, a Holocene coastal lake located in the Lofotens off the coast of northern Norway. These two lakes have vastly different environmental histories, the former a terrestrial lake formed from a meteor impact and never covered by continental ice sheets whereas the latter went from a coastal marine setting to a completely lacustrine environment due to isostatic rebound and sea level fluctuations. Their differences are considerable, however they provide the opportunity to compare Arctic lake systems to discern similarities and differences in their magnetic properties for application to future climatic investigations. Paleomagnetic measurements and down-core magnetic susceptibility were performed at the GFZ German Research Centre for Geosciences in Potsdam for Lake El'gygytgyn and at the Laboratoire de paleomagnétisme sédimentaire at ISMER for Heimerdalsvatnet. Rock magnetic properties were measured at the University of Massachusetts Amherst, Institute of Rock Magnetism, and/or Trinity College. These measurements included: magnetic susceptibility, hysteresis parameters, Curie temperatures, and low-temperature magnetic behavior. Imaging of magnetite grains was also performed. Magnetic susceptibility measurements in Lake El'gygytgyn suggested a correlation between glacials (interglacials) and low (high) susceptibility. The large range in susceptibility indicated there could be magnetite dissolution. The first study supported this hypothesis with evidence at low temperatures (10-35K) of minerals such as siderite, rhodochrosite, and/or vivianite which could form from iron released during dissolution. Marine Isotope Stage 31 was investigated for rock magnetic properties that could continue to support or oppose findings from the first study. It was determined the presence of siderite only occurred in interglacial periods whereas its absence (and probably presence of vivianite) related to glacial periods, indicating more reduced environments during glacials versus interglacials. Heimerdalsvatnet paleomagnetic data from the marine environment (lower part of the core) revealed scattered directions whereas data from the upper part of the core (lacustrine environment) showed better consistency. Rock magnetic measurements showed some variation downcore, however the measurements are not dependable since the amount of paramagnetic material was overwhelming compared to any ferromagnetic mineral present.

Thesis (Ph.D.)--The Ohio State University, 2006. / (UMI)AAI3238159. Adviser: K. C. Jezek. Source: Dissertation Abstracts International, Volume: 67-10, Section: B, page: 5629.

Thesis (Ph. D.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves196-212). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNR11592

Disposal of the UK's legacy nuclear waste is the biggest challenge facing the industry at present. There is currently no long term storage facility in the UK and the inventory is continually growing. This project investigates the role that digital geoscientific data collection, analysis and modelling techniques play in the search for, and development of, a Geological Disposal Facility (GDF), critically analyses classical techniques and new, digital methodologies to assess what their impact would be on any site investigation. The Borrowdale Volcanic Group outcrop in Cumbria, NW England was chosen as it provides an analogue to a higher-strength crystalline basement setting for a GDF. Terrestrial lidar and photogrammetric surveys were conducted at four locations around the study area. These provided information on the fracture geostatistics which are the main fluid migration pathways in the subsurface in the BVG. The mechanics of deformation are identified by analysing the clustering of data points via digital stereonet analysis. The analysis shows the rocks sampled are highly fractured and their orientations and dips reflected the extensional tectonism experienced in the area. These are in the form of adjacent sets trending broadly NNE-SSW and NNW-SSE at very high angler dips (~70 degrees). A new workflow developed for this work demonstrates how a potential site's fracture statistics, and indeed the 3D geology, should be investigated as part of future GDF site investigations. Areas of complex geology such as the BVG present many difficulties in interpretation and analysis due to the poorly constrained polyphase nature of the deformation. These complexities make characterisation and modelling highly problematic, and as such, areas of simpler geology should be investigated first. Assessments which were based on early geological studies using traditional field data collection techniques underestimated the impact of heterogeneity on fluid flow migration modelling within the subsurface. This suggests that, should a GDF should be developed in such a geological setting, huge difficulties may be encountered. These will be associated with the development of performance assessments and safety cases which are typically based on geological models that should use such complex data. In addition to this, datasets collected using digital methods are a powerful visualisation tools for communication of complex geology, that can be utilised in stakeholder engagement activities that will form a key part of any GDF development process.