ANDERSON, KATHERINE E.; EDGE, RUSSELL D.; HACKSTON, ABIGAIL J.; MARAJ, SHOBA; ROMANOWSKI, MICHAL J.; SEAMONS, REED L.; Sternberg, Ben K.; STOKES, PHILIP J.; THURNER, SALLY M.; University of Arizona (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2008-05-14)
      Groundwater resources are essential to support the growing population of Benson as well as the agriculture, and wildlife throughout the Middle San Pedro Basin. A refined model of the hydrogeologic framework within the region is necessary to allow for the most efficient allocation of the area’s ground water resources by city planners and water managers in charge of future development. New data were collected by the University of Arizona’s Geophysics Field Camp to update and improve this representation. This survey utilizes Controlled Source Audio Magnetotellurics (CSAMT) to characterize previously unstudied locations in the San Pedro Basin. CSAMT data were processed and interpreted using software from Zonge Engineering and Interpex Ltd. Seven receiver stations along a five-kilometer Middle San Pedro transect were used to determine the resistivities of several basin-fill units. Results show some resistivity variability with respect to depth among the sampled regions. In the simplest representation of the data, four layers were modeled. Resistivities ranged from 15-30 ohm-m in the near-surface units. Deeper units showed resistivities of 5-10 ohm-m. These results were plotted to help identify conductive aquitard (clay) and potentially more resistive aquifer units. This clay unit could correspond to a thin unit of the St. David Formation, which has previously been identified as a confining unit between two separate basin aquifers. CSAMT data indicate that the local bedrock is deeper than 500 m.
    • Controlled Source Audio Magnetotelluric (CSAMT) Surveys in the Tucson Mountains

      Fleming, John B.; Hafit, Husna D.; Khalid, Khaliza B.; Martinez, Jesse G.; Powell, Jonathan A.; Ren, Xin; Ridzuwan, Mohamad; Sternberg, Ben K.; University of Arizona (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2012-05-15)
      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.

      Barbato, Nicholas A.; Bingham, Peter D.; Conley, Michael C.; DeFilippo, Makko A.; Desser, Elizabeth M.; King, Christina A.; Lewis, Benjamin J.; McCarthy, Emily S.; Mendoza, Nirio; Rucker, Michael L.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2009-05-14)
      An interdisciplinary survey consisting of four geophysical methods was conducted on the western edge of the Apache Generating Station’s property in Willcox, Arizona. The aim of the survey was to apply various methods for the detection of earth fissures and desiccation cracks. The geophysical methods used were static magnetic field measurements, frequency domain electromagnetics (FEM), ground penetrating radar (GPR), and seismic. Two grids were delineated and surveyed by each method. Grid 1 was set up at a site containing a fissure with visible surface expression over some parts of the grid, and Grid 2 was set up at a site with little visible surface expression of the fissure, but was suspected to contain a fissure in the subsurface. At another location, northwest of the Apache Generating Station, three lines were surveyed in an area of known desiccation cracks. All of the methods showed an anomaly associated with the fissure in Grid 1. Furthermore, at locations where the fissure is not visible in Grid 1, there were still strong anomalies in line with the suspected location of the fissure extending below the surface. Magnetic data from Grid 2 suggests that magnetics may not be a useful method in subsurface earth fissure detection at this site, where we believe that the fissure is only a very small crack with small aperture at depth. The electromagnetic results from Grid 2 show anomalies extending from lines 1 through 5 where there is only minimal surface expression in lines 1 and 2 and no surface expression in lines 3-5. No anomaly was seen in the northern end of Grid 2. It was found that GPR in Grid 2 did not display conclusive results in distinguishing subsurface earth fissure anomalies from other anomalies, such as roots. Seismic lines in Grid 2 show anomalies in the profiles that could indicate the presence of earth fissures; however a thin high velocity horizon may appear as a subsurface fissure, and this made interpretations more challenging. At the desiccation crack site, there is evidence of a shallow feature, which we interpret to be a dessication crack and not an earth fissure. A dirt road was present at the desiccation crack site, and it is possible that the road may have produced some of the observed anomalies due to rain-water channeling effects. The locations of fissures were confirmed by trenches excavated at the locations where anomalies were visible in the geophysical data, but where the fissures were not exposed at the surface.

      Avanesians, Patrick; Daroch, Giancarlo A.; Fleming, John; Hundt, Stephen A.; Leake, Steven C.; Ojha, Lujendra; Sternberg, Ben K.; Wampler, David F.; University of Arizona (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2011-05-14)
      Transient Electromagnetic (TEM), Controlled Source Audio Magnetotellurics (CSAMT), Gravity, and Magnetic data were collected in the Tucson Mountains during the Spring semester, 2011. The goal was to investigate the extent of a low-resistivity porous sedimentary layer and faults that may form potential traps located under the surface volcanic layers, as interpreted by Lipman 1993. The sedimentary layer under the volcanics has the potential to be used for either water resources or compressed air storage to store solar energy. The results from the TEM and CSAMT surveys broadly correlated with the thickness of the volcanic layer and throw of the faults interpreted by Lipman, 1993. The gravity modeling suggested the faults may have a larger throw than what was indicated by the other methods. Because of the fundamental uncertainty in the densities to use in the modeling, it was concluded that the gravity modeling may not give as accurate a prediction of the structure in this region. For further investigation of the deep porous sedimentary layer, we suggest that TEM and CSAMT are the most effective methods.

      Aspiras, Gerald P.; Crawford, Matthew T.; Cylwik, Scott D.; Dangi, Tarun; Dewan, Milan M.; Hays, Naydene R.; Miller, Thomas E.; Sternberg, Ben K.; Thompson, Mayo; University of Arizona (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2006-05-07)
      Four geophysical surveys were conducted at the Nature Conservancy about 20 miles north of Benson, AZ, in the Upper San Pedro River Basin, in order to better understand the nature of the sub-surface features of the basin. The geophysical methods included TEM (Transient Electromagnetic), seismic, EM34 and magnetic surveys. The TEM, seismic and magnetic surveys were conducted perpendicular to the river basin while the EM34 lines followed the riverbed. The perpendicular surveys were divided into two regions, referred to as the South and North Lines. The TEM, seismic, and magnetic surveys revealed a consolidated bedrock structure at shallow depths (30-40 m) along the South Line. The feature has an east-west extension of approximately 500 meters, and is located just east of the San Pedro River. None of the perpendicular surveys were able to detect bedrock features along the North Line, implying that the depth to bedrock exceeds the maximum depth of this investigation (360 m). Both lines showed regions of high porosity, and, potentially, of saturated materials. These regions were more prevalent along the North Line, where numerous highly porous areas were detected at various depths (including one region beginning at a depth of 50 meters and extending at least to 360 m). The EM34 failed to detect any appreciable long-wavelength changes in conductivity along the riverbed, though localized point anomalies were found.
    • Geophysical Investigations near Yuma, Arizona

      Al-Zaabi, Mohamed; Eastman, Julie; Huebner, Laura; Muhlenkamp, Brianna; Riley, Jeannemarie; Rohe, Chris; Smith, Gwynneth; Souza, Deborah; Sternberg, Ben; Taft, Cristin M.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2005)
      VLF (Very Low Frequency), magnetic, TEM (Transient ElectroMagnetics), and Seismic were performed in Yuma, Arizona over two weekends in February and March of 2005. The targets of interest in Yuma included the depth to the shallow bedrock, the trace of the Algodones Fault, and the distribution and thickness of clay units. The VLF and magnetic surveys both proved not to be valuable for the interpretation of groundwater or bedrock depth. The Seismic surveys found a quartz monzonite horst structure at a depth of 8 meters and 250 in length and a graben at 8 meters depth and 48 meters in length. The TEM surveys were performed along Line 2 and Line 4 for Site One, Line 1 and Line 3 for Site Two, and SG1 line and SG2 line for Site Three. The TEM survey, located near the Seismic surveys, was in agreement with the findings of these Seismic surveys. At all sites, the TEM surveys were useful for determining depth to water table. At one site, the TEM survey mapped substantial near-surface clay layers.

      Sternberg, Ben K.; Al-mujaini, Ali A.; Ashley, Darin W.; Birken, Ralf; Crawley, Sean E.; Dean, Rayner W.; Glaccum, Matthew B.; Haack, Jerry M.; Hardin, Ernest L.; LaFiame, Lisa M.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1993-06-23)

      Bishop, Bradley P.; Casto, Daniel W.; Chama, Mukonde; Heinecke, Justin M.; Henley, Michael L.; Malsom, Andrew A.; Mason, Mark S.; Miller, Alisa C.; Mwewa, David C.; Potts, K. Greg; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2000-05-07)
      During the Spring semester, 2000, the University of Arizona Geophysics Field Camp (GEN/GEOS 416/516 class) conducted geophysical surveys in the vicinity of the United Musical Instruments facility near Nogales, Arizona. This site is a super-fund site, due to the presence of contaminants, including TCE, in the ground water. The contaminants are presumed to have come from cleaning and electroplating solutions, which had been dumped into a small pond on the UMI property. The U.S. Geological Survey provided the funding for our study. The objective was to determine subsurface structural information that would help interpret possible future movement of the contaminant plume. Transient electromagnetic (TEM) data were most useful for interpreting the subsurface geohydrology. Water table was found at a depth of approximately 30 meters, north of the UMI building. A particularly interesting feature in the TEM data was a high-resistivity anomaly and an associated low-resistivity anomaly 10 to 1 00 meters northeast of the UMI building. We interpret the high-resistivity anomaly as possibly being due to an impermeable levee that was associated with a buried stream channel and the low-resisitivity anomaly as possibly being due to the pooling of conductive contaminated fluids against the impermeable levee. DC resistivity surveys were dominated by cultural coupling, which was pervasive m the survey area. Magnetic readings were used to help locate potential cultural interference. Gravity surveys indicated a low-density anomaly, which may be due to a buried stream channel. This feature could be related to the features mapped with the TEM surveys. The seismic survey indicated progressively more compacted and cemented alluvium, overlying the Nogales formation. The seismic data did not provide any direct information about the geohydrology of the area

      Bennett, Jesse E.; Bowler, Anthony T.; Cavabaugh, William R.; Glass, Aaron J.; Green, John D.; Katbah, Maher M.; Murphy, George P.; Pepe, Jennifer L.; Poulton, Mary M.; Qin, Jizeng.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1991-03-27)

      Birken, Ralph A.; Hassouneh, Mohammed H.I.; Heath, Gail; LaBrecque, Douglas J.; Lindsay, David S.; McGraw, Matthew D.; Milton, Stuart L.; Mullarky, Leo J.; Nguyen, Qui P.; Nickerson, Mark D.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1994-06-22)

      Andrews, Joseph N.; Backes, Brian D.; Balay, Scott; Barry, James F.; Birken, Ralf A.; Brown, Marshall P.; Davenport, Michael S.; Debroux, Patrick S.; Dwinnell, Heidi K.; Franklin, Tiffany D.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1995-06-21)

      Buggenhagen, John E.; Clote, Valerie J.; Dixon, Angela M.; Fitzsimmons, Clark D.; Forman, Katherine C.; Gain, Erik R.; Galloway, Brian K.; Green, Rori L.; Hammers, W. Bre; Hurguy, Jr., William; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1992-06-22)
    • Geophysical Surveys in the Pima Mining District, Arizona Volume II

      Alalawi, Saleh S. N.; Albehlany, Salah S. H.; Aldossary, Abdulaziz F.; Alhashimi, Rashid A.; Almurshidi, Abdulsam M.; Cathcart, Laura L.; Cole, Sherill L.; Crews, Joseph A.; Crouthamel, David Roger, 1963-; Didace, Didi; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1989-02-06)
    • Geophysical Surveys in the Pima Mining District, Arizona Volume I

      Alalawi, Saleh S. N.; Albehlany, Salah S. H.; Aldossary, Abdulaziz F.; Alhashimi, Rashid A.; Almurshidi, Abdulsam M.; Cathcart, Laura L.; Cole, Sherill L.; Crews, Joseph A.; Crouthamel, David Roger, 1963-; Didace, Didi; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1989-02-06)
      Geophysical surveys were conducted in the Pima mining district by students from the University of Arizona. The surveys were concentrated along section B-B' from Cooper (1973). The objectives of this survey included: teaching geophysical techniques, mapping regional structure along this profile, and determining which geophysical techniques were most useful for regional .mapping in this area. Controlled source audio-frequency magnetotelluric (CSAMT) surveys successfully mapped depth to basement along this profile. Seismic refraction surveys were not able to map depth to basement. Either the depth to basement was beyond the range of the arrays used in this experiment or there is insufficient contrast in the velocity between the basement and the overlying rocks. A test of the seismic reflection method was carried out using a walk-away noise spread. Possible reflections from basement were noted but were not sufficiently diagnostic to be routinely use able.

      Barber, Lorraine; Crum, Greg; George, David; Ikeda, Carrie; Irvine, Graham; LaBrecque, Doug; LeGrand, Jonathon; Lim, Andrew; Loomis, John; McGill, Robert; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1997-06-01)
    • Geophysical Surveys near Chino Valley, Arizona

      Al-senani, Haitham S.; Cox, Melissa R.; Duke, Vasco S.; Duncan, Laurel M.; El-Kaliouby, Hesham; Gandler, Greg L.; Geauner, Scott A.; Manuel, Justin; Powell, Kathy S.; Sternberg, Ben K.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2003-05-07)
      Four different geophysical methods were used near Chino Valley, Arizona in order to map a suspected andesite intrusive, identified as plug 15, which had originally been found using aeromagnetic data already acquired over the area. Magnetic, transient electromagnetic, seismic, and gravity measurements were collected between 3/1/2003-3/2/2003 and 3/22/2003-3/23/2003. The surveys were located near the center of section 35, township 17 North, Range 2 West, just north of Chino Valley, AZ. The magnetic and TEM surveys provided the best indication of the location and depth of the plug. The north-south spatial extent of the plug was estimated to be approximately 600 meters. The depth to the top of the plug was found from the TEM survey to be approximately 300 meters at the center of the survey. The seismic survey did not reach deep enough to find the andesite anomaly and the gravity survey did not appear to be affected by the plug. Magnetic, TEM, and seismic surveys were also performed at another site located approximately 1.25 km northeast of plug 15. The seismic survey did not reach deep enough and the magnetic survey was too short to provide a depth interpretation. The single TEM sounding measured a very high resistivity (approximately 900 ohm-m) at this site.
    • Geophysical Surveys near Fort Huachuca, Arizona

      Call, Christopher J.; Gleason, Arianna E.; Kaunda, Rennie B.; Meneill, Michael J.; Mkandawire, Emmanuel; Palmer, Joe D.; Portney, Barrie S.; Sternberg, Ben K.; Tembo, Jones; Wagner, Shanda L.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2002-05-04)
      The United States Geological Survey (USGS) has been studying the water resources in the vicinity of Fort Huachuca, Arizona. As a part of this study, they contracted an Airborne Electromagnetic (AEM) survey of the region, which was flown in 1997. During the spring semester of 2002, the University of Arizona Geophysics Field Camp class conducted Transient Electromagnetic (TEM) surveys at five locations near AEM flight lines in order to provide an independent test of the resistivity structure. We used 100 X 100 m transmitting loops. A central induction loop array was employed where the transient decay voltage after transmitter turn off was recorded in the center of the transmitter loop. The TEM data were inverted using a smooth modeling program from Zonge Engineering. The resulting apparent resistivity cross sections, in general, showed a resisitivity structure that was similar to the AEM cross sections down to the depth of the investigation of the TEM survey (approximately 200 m). The surface layers (zero to 50 meters) showed high resistivity (30 to 300 ohm-m) and deeper layers showed lower resistivities (10- 30 ohm meters). We also recorded low-induction number (LIN) EM surveys over a sink hole feature in this area. There was a pronounced conductivity high coincident with the sinkhole. Background conductivity readings were typically 10-15 mS/m and over the sinkhole feature the conductivity readings were typically 20-25 mS/m.
    • Geophysical Surveys near Old Yuma Mine, Tucson Mountains, Arizona

      Chon, Enrique; Gabriel, Matthew; Harders, Sara; Hou, Xiaobo; Layton, Riley; Okbay, Meron; Roth, Karen; Rzechula, Lisa; Sternberg, Ben; Tuten, Thomas; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 2016-07-04)
      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.

      Betts, Nathan K.; Chongo, Poto; Dieter, Nina K.; Elliott, Blake J.; Geeslin, Gretchen R.; Henley, Maren B.; Marcus, Matthew W.; Marquez, Matthew H.; Ntambakwa, Eric M.; Peterson, James A.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1998-05-01)

      Cisneros, Gabriel; Dearman, Marnee M.; Dodds, Brian E.; Edwards, Nils K.; El-Kaliouby, Hesham; Gajda, Charles E.; Henley, Michael L.; Killian, James R.; Kyselka, Rebecca C.; Moore, Jeffrey R.; et al. (LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ), 1999-06-01)
      A geophysical study of the Patagonia-Sonoita Nature Conservancy property was carried out to determine the depth to bedrock and the geometry of the underlying basin in the area. The survey was part of the ongoing U.S. Geological Survey studies of the region. CSAMT, TEM, DC Resistivity, Seismic, Gravity, and Magnetic surveys were performed. Many of the surveys were not able to map depth to bedrock because the depth of penetration of these surveys was less than the large depth to bedrock, which we encountered in this area. The best estimate of depth to bedrock in the center of the valley is of the order of one kilometer, as identified by the CSAMT surveys. The CSAMT survey found a significant low-resistivity anomaly in the vicinity of the Nature Conservancy Visitor Center. This low-resistivity anomaly could be due to clay-rich rocks or possibly mineralized rocks. Magnetic and TEM anomalies also occurred in the same area as the CSAMT low-resistivity anomaly. Seismic surveys showed a loosely consolidated surface layer above more consolidated alluvium. The model from the · Gravity survey shows an extensive alluvial basin overlying rhyolite with high and low-angle faults.