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.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624630 |
| Date | 04 July 2016 |
| Creators | Chon, Enrique, Gabriel, Matthew, Harders, Sara, Hou, Xiaobo, Layton, Riley, Okbay, Meron, Roth, Karen, Rzechula, Lisa, Sternberg, Ben, Tuten, Thomas, Weber, Aiza |
| Contributors | University of Arizona |
| Publisher | LASI Laboratory for Advanced Surface Imaging, The University of Arizona (Tucson, AZ) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | Book |
| Rights | Copyright © Arizona Board of Regents |
| Relation | LASI-16-1, http://www.lasi.arizona.edu/ |
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