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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Visualisation of multi-source archaeological geophysics data

Schmidt, Armin R. January 2002 (has links)
No
152

Remote Sensing and Geophysical Prospection.

Schmidt, Armin R. January 2004 (has links)
No / In archaeological prospection, computer processing is essential for all stages of data manipulation. This article investigates the contributions which informatics has made in the past and looks at its potential for the future. It is shown how the workflow of satellite imagery, aerial photography and geophysical prospection can be broken down into measurements, acquisition, processing, visualisation and interpretation. Based on these categories, the advantages of digital data manipulations are explored with individual examples. It is shown that informatics can greatly assist with the final archaeological analysis of the measurements but that human experience and assessments are crucial for a meaningful interpretation.
153

Geophysical survey on a southern French oppidum.

Armit, Ian, Horsley, T., Marty, F. January 2008 (has links)
No / No Abstract
154

Petrographic, Geochemical, and Geophysical Well Log Assessment of the PrecambrianBasement in Eastern Ohio

Gibbs, Eric W. 22 September 2020 (has links)
No description available.
155

Processing and Interpretation of Illinois Basin Seismic Reflection Data

Gigandet, Katherine M. 10 June 2014 (has links)
No description available.
156

Detecting trends in the prediction of the buried past: A review of geophysical techniques in archaeology.

Gaffney, Christopher F. January 2008 (has links)
No / Geophysical survey techniques are a highly visible part of the scientific toolkit that is now used by archaeologists. In this paper, the history of the use of geophysical techniques in archaeology will be discussed, as will significant research themes associated with the most widely used prospecting devices. It is apparent that while the use of geophysical techniques is at an all-time high, there are many key areas where prospecting is rapidly developing. Some of the advances relate to fundamental aspects of the techniques, while others dictate how we undertake survey in the future. There is a movement away from pre-gridded survey areas towards real-time GPS for navigation. This allows greater integration, or fusion, of disparate data sources using visualization techniques derived from associated disciplines. The analysis of landscapes has become a major component of the application of new technology and there are many challenges to be tackled, including how to analyse and interpret significant archaeology within large-scale, data-rich, multi-technique investigations. The reflective nature of the review acknowledges the important role of Archaeometry in the development of archaeological geophysics.
157

A geophysical survey of the Kituhwa Mound (31SW2) and the surrounding area (31SW1), Swain County, North Carolina

Moore, Palmyra Arzaga, January 2009 (has links) (PDF)
Thesis (M.A.)--University of Tennessee, Knoxville, 2009. / Title from title page screen (viewed on Oct. 22, 2009). Thesis advisor: Gerald F. Schroedl. Vita. Includes bibliographical references.
158

3-D GEOPHYSICAL MODELLING OF CONFIRMED AND SUSPECTED IMPACT CRATERS IN SOUTHERN ONTARIO, CANADA: CONSTRAINING STRUCTURE ORIGIN, SUBSURFACE GEOLOGY AND POST-IMPACT MODIFICATION

Armour, Mary-Helen January 2022 (has links)
Abstract Impact cratering is a fundamental geomorphic process on planetary surfaces. More than 60% of known hypervelocity impact craters on Earth are either partially or completely buried beneath post-impact sediments and one-third have been discovered with geophysical methods. In this thesis, geophysical surveys (gravity, magnetics, seismic, bathymetric mapping) were conducted at the deeply buried (>400 m) Holleford impact crater (~2.35 km) and two probable impact structures (Charity Shoal, Skeleton Lake) in southern Ontario, Canada. 3-D potential field models were constructed to determine the subsurface geology and buried crater morphology, and to evaluate evidence for possible impact versus endogenic origins. Holleford Crater is a deeply buried, Late Proterozoic-Early Cambrian (ca. 550 ±100 Ma) simple impact crater (~2.4 km) in southeastern Ontario, Canada. Land-based magnetic and gravity surveys and modelling were conducted in this study, recorded a ~ -3 mGal Bouguer anomaly and small (~30 nT) magnetic anomaly over the crater basin. 3-D gravity modelling revealed a deeply buried simple impact basin in Mesoproterozoic basement with an estimated rim-to-rim diameter (D) of 1.8-2 km, a residual rim height of ~20-30 m and true depth (dt) >400 m. The southeast crater rim is dissected by a 150 m deep, 400 m wide erosional channel produced by fluvial rim dissection. The outflow is infilled by >50 m of Late Cambrian clastic sediments, indicating a probable Late Proterozoic to Early Paleozoic impact event. Charity Shoal is a 1.2-km-diameter, 20 m deep, circular bedrock shoal in eastern Lake Ontario. Marine seismic profiling and total field magnetic surveys (140-line km) were conducted over a 9-km2 area and combined with available multi-beam bathymetric data to evaluate the subsurface geology and structure origin. Seismic surveys revealed ~30 m of Quaternary sediments overlying Middle Ordovician (Trenton Group) carbonates in the central basin and evidence for folding and faulting of the structure rim. Magnetic surveys recorded an annular magnetic high (> 600 nT) and a central magnetic low (~500-600 nT) coincident with a ~-1.7 mGal Bouguer gravity anomaly. The continuity of Middle Ordovician bedrock below the structure rules out a post-Paleozoic intrusion and a pre-Paleozoic intrusion is ruled out with the gravity anomaly. A deeply-buried (> 450 m) impact crater is the only scenario consistent with geophysical evidence. The crater has a rim-to-rim diameter of ~1.2 km, and rim height of ~15-20 m. A 100-m wide breach in the southwestern rim records a possible outflow channel. Skeleton Lake is a suspected (~4.0 km) Paleozoic-age impact structure in Muskoka, Ontario. The lakebed morphology, subsurface structure and possible impact origin were investigated with high-resolution geophysical surveys (magnetics, bathymetry; ~140 line-km) and 3-D magnetic modelling. Bathymetric data reveal a deep (>65 m) central basin with arcuate (Paleozoic?) bedrock ridges that rise >30 m above the southwestern lakebed. Magnetic surveys recorded a >700 nT magnetic low, which truncates northwest-southeast regional magnetic trends. Low-amplitude, northwest-trending magnetic lineaments delineate basement shear zones below the basin centre. Through-going magnetic lineaments and lack of thermal alteration (e.g., dikes, fenitization) in Mesoproterozoic rocks indicate a volcanic origin is unlikely. A 1.2 km diameter volcanic plug with an Early Cambrian remanence (D = 82.2°, I = 82.7°) can reproduce some aspects of the magnetic anomaly but is at odds with the Bouguer gravity anomaly (~ -3 mGal). Forward modelling of a crater-form basin with induction and remanence magnetization yielded an estimated structure depth of ~1200 m. The basement surface model shows a complex basement topography with no apparent rim structure and elevated ‘pinnacles’ that may represent eroded remnants of a central uplift or a highly-dissected basement topography. The structure apparent diameter (> 4.2 km) and complex basement topography suggest a heavily-modified transitional crater, similar with the Gow (Saskatchewan, Canada) and Kärdla (Estonia) impact structures. This thesis demonstrates the subsurface exploration of confirmed and suspected impact structures, integrating seismic, potential field (magnetics, gravity) and digital elevation data within a 3-D geophysical modelling workflow. The approach provides important new insights into the surface and subsurface geology, morphology, and post-emplacement modification of the Holleford impact crater, and new geophysical constraints for evaluating two suspected impact structures. Geophysical data confirm that Charity Shoal and Skeleton Lake are deep-seated, crater-form depressions in Mesoproterozoic basement rocks. The weight of geophysical and geological evidence points to impact cratering processes as opposed to an endogenic (volcanic) origin for both structures. / Thesis / Doctor of Science (PhD)
159

Sustainable Mining - Solving the Problem of Chalcopyrite Treatment/Processing - Leaching, Solvent Extraction & Flotation

Dakubo, Francis January 2016 (has links)
Chalcopyrite ore forms the significant fraction of copper deposits in the earth crust. However, it is also the most difficult to treat using conventional ferric leaching methods. Smelting and electro-refining are currently the methods used in treating chalcopyrite concentrate obtained from froth flotation. Due to the ever increasing environmental requirements on smelters by the Environmental Protection Agency, new smelters are scarce in the United States. The scarcity of smelters has led to the urgent need to find a novel leaching method for the abundant chalcopyrite deposits in the USA and the rest of the world. This chapter(one) of the dissertation, therefore, investigated the leaching of chalcopyrite ore at pH 2 using a newly discovered oxidant (peroxodisulfate). Our results show that chalcopyrite leaching using peroxodisulfate follows a surface reaction shrinking core model. The activation energy of chalcopyrite leaching using peroxodisulfate ion was calculated as 41.1 kJ mol⁻¹. We also report that the leaching of chalcopyrite ore is affected by particle size and that stirring hurts leaching of chalcopyrite. Additionally, we found that peroxodisulfate can produce from sulfuric ions electrochemically. Hydrogen peroxide, permanganate, peroxodisulfate and ferric ions are all strong oxidants that have been researched in production pregnant leach solution (PLS) from chalcopyrite ore leaching. Because, solvent extraction is the next step in the recovery of copper from pregnant leach solutions (PLS). The questions, therefore, arises as to the fate of the organic extractant used in solvent extraction coming in contact with strong oxidant residual in the PLS. In chapter two of the dissertation, we studied the effect of strong oxidant residual in PLS on the degradation of organic extractants during solvent extraction of copper. Exposed organic extractants were analyzed using interfacial tension(IFT), Fourier Transform Infrared (FTIR) spectroscopy and CG LS. The results obtained from IFT and FTIR analysis, show no effect on the organic extractants exposed to sunlight and PLS containing the residual strong oxidant. Finally in chapter 3, the dissertation exams alternative water source for the flotation of chalcopyrite. Mineral flotation is a water-intensive process in mining. In order to sustain mining operations such flotation, which rely heavily on water, chapter 3 of the dissertation looks at using alternative water sources (in this case reclaimed wastewater) in the flotation of chalcopyrite ores; this effort is to limit the mining industries dependence on fresh ground water particularly in the Southwest of United States where water is a scarce commodity. The research studied the effect of reclaimed waste water on chalcopyrite flotation via contact angle and surface energy measurements. Furthermore, atomic force microscopy (AFM) and flotation tests were used to supplement the findings from contact angle and surface studies. We conclude here that the contact angle of a pure chalcopyrite surface was determined to be 75.6 degrees. We also found that pure chalcopyrite mineral surface is slightly polar with surface energies γCuFeS2^(LW) = 41.4 mJ/m² (apolar), γCuFeS2^(AB) = 2.9 mJ/m² (polar). The high value of the surface energy indicates pure chalcopyrite surface is slightly hydrophobic.
160

A New High-Resolution Electromagnetic Method for Subsurface Imaging

Feng, Wanjie January 2016 (has links)
For most electromagnetic (EM) geophysical systems, the contamination of primary fields on secondary fields ultimately limits the capability of the controlled-source EM methods. Null coupling techniques were proposed to solve this problem. However, the small orientation errors in the null coupling systems greatly restrict the applications of these systems. Another problem encountered by most EM systems is the surface interference and geologic noise, which sometimes make the geophysical survey impossible to carry out. In order to solve these problems, the alternating target antenna coupling (ATAC) method was introduced, which greatly removed the influence of the primary field and reduced the surface interference. But this system has limitations on the maximum transmitter moment that can be used. The differential target antenna coupling (DTAC) method was proposed to allow much larger transmitter moments and at the same time maintain the advantages of the ATAC method. In this dissertation, first, the theoretical DTAC calculations were derived mathematically using Born and Wolf's complex magnetic vector. 1D layered and 2D blocked earth models were used to demonstrate that the DTAC method has no responses for 1D and 2D structures. Analytical studies of the plate model influenced by conductive and resistive backgrounds were presented to explain the physical phenomenology behind the DTAC method, which is the magnetic fields of the subsurface targets are required to be frequency dependent. Then, the advantages of the DTAC method, e.g., high-resolution, reducing the geologic noise and insensitive to surface interference, were analyzed using surface and subsurface numerical examples in the EMGIMA software. Next, the theoretical advantages, such as high resolution and insensitive to surface interference, were verified by designing and developing a low-power (moment of 50 Am²) vertical-array DTAC system and testing it on controlled targets and scaled target coils. At last, a high-power (moment of about 6800 Am²) vertical-array DTAC system was designed, developed and tested on controlled buried targets and surface interference to illustrate that the DTAC system was insensitive to surface interference even with a high-power transmitter and having higher resolution by using the large-moment transmitter. From the theoretical and practical analysis and tests, several characteristics of the DTAC method were found: (1) The DTAC method can null out the effect of 1D layered and 2D structures, because magnetic fields are orientation independent which lead to no difference among the null vector directions. This characteristic allows for the measurements of smaller subsurface targets; (2) The DTAC method is insensitive to the orientation errors. It is a robust EM null coupling method. Even large orientation errors do not affect the measured target responses, when a reference frequency and one or more data frequencies are used; (3) The vertical-array DTAC method is effective in reducing the geologic noise and insensitive to the surface interference, e.g., fences, vehicles, power line and buildings; (4) The DTAC method is a high-resolution EM sounding method. It can distinguish the depth and orientation of subsurface targets; (5) The vertical-array DTAC method can be adapted to a variety of rapidly moving survey applications. The transmitter moment can be scaled for effective study of near-surface targets (civil engineering, water resource, and environmental restoration) as well as deep targets (mining and other natural-resource exploration).

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