GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 107-1
Presentation Time: 9:00 AM-6:30 PM


HICKS, Cyanna L., School of Earth and Sustainability, Northern Arizona University, 625 S Knoles Dr, Flagstaff, AZ 86011, PORTER, Ryan C., School of Earth Sciences and Environmental Sustainability, Northern Arizona University, PO Box 4099, Flagstaff, AZ 86011-4099, UMHOEFER, Paul J., School of Earth and Sustainability, Northern Arizona University, Box 4099, Flagstaff, AZ 86011, KENNEDY, Jeffrey, U.S. Geological Survey, Arizona Water Science Center, 520 N. Park Avenue, Tucson, AZ 85719 and SPRINGER, Abraham E., Department of Geology, Northern Arizona Univ, Box 4099, Flagstaff, AZ 86011

The Basin and Range province includes much of the southwestern United States and formed due to lithospheric extension that initiated in the Oligocene and Miocene periods. Basin and Range style extension is characterized by high-angle and low-angle normal faulting that offsets mountain ranges from large sediment-filled basins. These sedimentary basins commonly store groundwater, and, as much of this region is arid, groundwater is an important resource for human consumption, agriculture, and industry.

The study area is located in the Maricopa-Stanfield and Eloy (Picacho) basins between Phoenix and Tucson in southern Arizona. Many small farming communities within this region rely on water for their livelihoods. Since 1993, the Central Arizona Project (CAP) has supplied water from the Colorado River to this area. However, due to the rapid growth of Arizona and the rest of the Colorado River Basin states, as well as climate-change induced drought, the long term supply of water is uncertain within the region.

Determining the content, quantity, and suitability of water for human consumption in these basins will allow these communities to better plan future water use. To better understand the basins, their aquifers, and regional water storage, we collected gravity data from the Maricopa-Stanfield and Eloy basins. We then combined these data with previously collected well log and seismic data to better characterize the geologic structure and potential aquifers. Initial results show negative gravity anomalies over the basins, consistent with basin fill.

Ongoing work involves modelling gravity data to better understand how extension is accommodated in the Basin and Range Province in the Western United States. Structurally, these basins will show more about the accommodation zones between metamorphic core-complexes (the ranges), as well as the cause of the orientation of the core-complexes in Southern Arizona.