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The AAPG/Datapages Combined Publications Database

Utah Geological Association


Geology and Geologic Resources and Issues of Western Utah, 2009
Pages 388-410

Road Log Utah Geological Association 2009 Field Conference, September 18 and 19, 2009

Joseph S. Gates


This two-day field trip is primarily a hydrogeologic tour of the basins of west-central Utah but includes some metallic mineral exploration stops, a sequence- stratigraphy stop, a stop at a cement plant with associated quarries, an optional tour of Lehman Caves, an evening lecture on the structural framework of western Utah and eastern Nevada, and the general geology of the field trip route. Compiled by Joseph S. Gates from many sources, with contributions from Bill Case, Gary Dixon, Lucy Jordan, Ken Krahulec, Scott Ritter, Peter Rowley, Chris Staargaard, Bryce Tripp, and John Zimmerman.

We will see a lot of Paleozoic carbonate rocks—limestones and dolomites—on the trip (see map). In places the section of Cambrian through Permian rocks is up to 30,000 ft thick and is predominately carbonates, deposited in a shallow warm ocean when Utah was near the west coast of North America.

The basins of west-central Utah and eastern Nevada have two different aquifers—basin-fill aquifers are the most important but the carbonate-rock aquifer or aquifers is also important, at least locally. However, except at a few locations, we know much less about the carbonate-rock aquifer, specifically the degree of its interconnection with the basin-fill aquifer and its effective extent, properties of transmissivity and storage, paths of ground-water flow, and the quality of its water. Over the next two days, we will discuss some of these questions.

We will see two different classes of springs (and some in between): (1) Local springs obtain their water from a limited area, are close to their areas of recharge, commonly have low rates of discharge but can have significant seasonal variation in discharge, have low temperatures that reflect shallow depths of circulation, and generally are fresh. (2) Regional springs obtain their water from large areas and can be far from their recharge areas, generally have large discharge (commonly more than 1000 gallons per minute [gal/min]) and little seasonal variation in discharge, have higher temperatures reflecting deeper circulation, and range from fresh to saline.

On the trip are thermal springs (and a thermal well)—warm springs with water temperatures more than 10°F above the mean air temperature, and hot springs with water temperatures more than 100°F. In terms of salinity, water with a dissolved-solids concentration of less than 1000 milligrams per liter (mg/L) is considered fresh (less than 500 mg/L best for drinking water), 1000 to 3000 mg/L is slightly saline, 3000 to 10,000 mg/L is moderately saline, 10,000 to 35,000 mg/L is very saline, and more than 35,000 mg/L is briny.

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