http://hdl.handle.net/10150/599246 Sun, 09 Jul 2017 17:53:03 GMT 2017-07-09T17:53:03Z http://hdl.handle.net/10150/624632 Title: Geophysical Surveys Near Tucson Electric Power Sundt Generating Station Author: Alghannam, Lujain Ali; Ayyad, Wadyan Osama; Do Lago Montenegro, Carla Gabriela; Feng, Wanjie; Jones, Christopher A.; Samoylov, Mikhail D.; Sternberg, Ben K.; Tso, Chak Hau; Wright, Sean T. Abstract: Tucson Electric Power (TEP) is carrying out subsurface investigations in order to locate more groundwater for cooling at the Sundt power-generating plant. To assist with this investigation, the University of Arizona GEN/GEOS 416/516 Field Studies in Geophysics class conducted geophysics surveys in an area just south of Davis-Monthan Air Force Base and between UTM coordinates 508,555 to 511,753 East and 3,553,705 to 3,556,895 North. Four geophysics methods (Gravity, Magnetics, Transient Electromagnetics (TEM), and Passive Seismic) were employed to locate a postulated fault, which may be correlated with ground water flow. A broad regional magnetic anomaly was mapped, as the magnetic field decreases steadily from NE to SW. There are no significant magnetic field anomalies that could be related to a potential fault. The Gravity results show a regional gravitational gradient, steadily decreasing from NE to SW, with a large isolated anomaly apparent around 1500m from the base station at the NE corner of the survey area. But, this large anomaly is a localized, and does not appear on the adjacent parallel survey lines, therefore it is not related to a potential fault contact. The Passive Seismic survey detected a deep boundary at 100m to 160m in elevation, but the depths interpreted from the 11 stations are scattered and do not show a clear trend. The Transient Electromagnetic (TEM) data show a consistent difference in depth to a low-resistivity layer along the profile line. The four TEM stations north of Interstate 10 (I10) have an average elevation for the 10 Ohm-m contour line of 720 meters. The four TEM stations south of I10 have an average elevation for the 10 Ohm-m contour line of 670 meters. This offset may be related to the postulated fault. Sat, 10 May 2014 00:00:00 GMT http://hdl.handle.net/10150/624632 2014-05-10T00:00:00Z http://hdl.handle.net/10150/624631 Title: Geophysical Surveys Near Tucson International Airport Author: Alam, Alaa E.; Alabkari, Mohammed; Albahrani, Ahmed Mohammed A.; Aljarbou, Abdulrahman M.; Dominguez, Ada R.; Ghallab, Mohammed; Khalid, Khaliza Binti; Keske, Amber L.; Morrell, Sophie; Sternberg, Ben K.; Feng, Wanjie; Zapata-Ríos, Xavier Abstract: The Tucson International Airport Area (TIAA) Superfund site is an approximately ten square mile area in southeast Tucson, Pima County, Arizona in which several known contaminated water plumes have been identified, which are the result of improper disposal of industrial waste from multiple sources during the past sixty years. The most prominent of these contaminants are 1, 4-dioxane, hexavalent Chromium, and trichloroethylene (TCE), which exist in varying concentrations throughout the site. Groundwater contamination in Tucson was first identified in the 1950’s; however TIAA was not recognized as a Federal Superfund site until 1982. Since then, much work has been carried out in an attempt to fully understand and remediate the contamination in the area. This study focusses on four areas within the TIAA: Samsonite North, Aero Park Blvd South (EW line), Aero Park Blvd South (NS line), and EPA-03. Several geophysical techniques have been used to understand the subsurface structure in the area and to better understand the contamination plume and its movement. Using the Transient Electromagnetic (TEM) technique at three sites: Samsonite North, Aero Park Blvd South (NS line and EW line), and EPA-03, it was found that there was a low-resistivity region going through the EPA-03 site, two low-resistivity regions through Aero Park Blvd South (NS line), and three low-resistivity zones through Aero Park Blvd South (EW line). These channels were consistent with the overall orientation of water flow in the region which is toward the Northwest. These zones may indicate higher moisture content, and this may be caused by porous, water-filled channels passing through the sites. These zones could also indicate non-porous clay-rich regions, which would also be low resistivity. The effect of a pipeline on the measurements in the Samsonite North area made it difficult to reach any useful conclusions at this site. Wed, 15 May 2013 00:00:00 GMT http://hdl.handle.net/10150/624631 2013-05-15T00:00:00Z http://hdl.handle.net/10150/624630 Title: Geophysical Surveys near Old Yuma Mine, Tucson Mountains, Arizona Author: Chon, Enrique; Gabriel, Matthew; Harders, Sara; Hou, Xiaobo; Layton, Riley; Okbay, Meron; Roth, Karen; Rzechula, Lisa; Sternberg, Ben; Tuten, Thomas; Weber, Aiza Abstract: To assist the United States Geological Survey with an on-going groundwater study around Old Yuma Mine in Tucson, Arizona, the University of Arizona GEN/GEOS 416/516 Field Studies in Geophysics class conducted geophysical surveys along two transects near the mine. Transect 1 was situated across the mine site; Transect 2 was located to the northeast in a nearby residential area. The methods used were gravity, magnetics, transient electromagnetics (TEM) and inductive electromagnetics (Geonics EM-31, and Geonics EM-34). The goal was to use these data to investigate the subsurface density, magnetic susceptibility, and electrical conductivity contrasts. A large gravity anomaly was observed on Transect 1 where it crosses both a mapped fault and the Old Yuma Mine; the anomaly is thought to represent a density contrast related to the Mine and fault. A smaller gravity anomaly was observed on Transect 2, corresponding in location along the profile to a large anomaly in the Transect 2 magnetics data. These anomalies are possibly related to the local lithology. A second magnetics anomaly was observed on Transect 1; this anomaly was also visible in the EM-31 and EM-34 data and could be due to the presence of a nearby wash. Other variations in the magnetics and EM-31/34 data consisted of narrow peaks associated with cultural interference, and the EM-31/34 data showed no large conductivity change in the shallow sediments. Interpretation of TEM data for Transect 1 was limited by the wide station spacing; much of the cross-section’s resistivity contrasts were interpolated over a large distance. The TEM cross-section for Transect 2 displayed higher resistivity on the northwest side and lower resistivity on the southeast side of the transect. Since the mapped fault, if projected northwards, would pass through the middle of Transect 2, it is thought that this resistivity contrast represents the location of the fault. It is hoped that the results of these surveys will be beneficial to the USGS in further work at Old Yuma Mine. Mon, 04 Jul 2016 00:00:00 GMT http://hdl.handle.net/10150/624630 2016-07-04T00:00:00Z http://hdl.handle.net/10150/624629 Title: Controlled Source Audio Magnetotelluric (CSAMT) Surveys in the Tucson Mountains Author: Fleming, John B.; Hafit, Husna D.; Khalid, Khaliza B.; Martinez, Jesse G.; Powell, Jonathan A.; Ren, Xin; Ridzuwan, Mohamad; Sternberg, Ben K. Abstract: Controlled Source Audio-Magnetotellurics (CSAMT) surveys were conducted in 2012 in the Tucson Mountains as a continuation of the 2010 and 2011 Laboratory for Advanced Subsurface Imaging (LASI) field studies in this area. This geologic setting was chosen for its high-resistivity impermeable volcanic layer overlaying porous sedimentary layers. This type of structure has potential for water resources and as a reservoir for compressed air energy storage (CAES). The data from 2,500 meters of CSAMT survey lines generated 900 meter-deep resistivity versus elevation cross-sections and six plan maps of the depth and elevation to the buried conductive layer. Our results are generally in agreement with the geologic cross sections developed by Lipman (1993) and previous TEM data that confirmed the presence of a deep conductive layer beneath a resistive volcanic sequence. Tue, 15 May 2012 00:00:00 GMT http://hdl.handle.net/10150/624629 2012-05-15T00:00:00Z