UTSA research sheds light on Central Texas geology and climate change

Geology
Geology

UTSA geology researchers

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(Dec. 2, 2009)--Research projects by Stuart Birnbaum, UTSA associate professor of geological sciences, and Daniel Lupton, a UTSA master's student in geological sciences, reveal new information about Central Texas' climate and water sources.

Birnbaum's team researched the ancient climate preserved in the chemical signature of samples from Kimble County, Texas, by taking rock samples from a 12-meter cliff exposure of the Hensel paleosol, an ancient soil estimated to be approximately 112 million years old.

"Our research is significant, because it could help us calculate the rate at which climate change took place in Earth's pre-human past," said Birnbaum. "Generally, we've learned that the climate 112 million years ago in what is now Central Texas was warm and arid, similar to what we see today. Once we learn how long it took the Hensel paleosol to form, we'll be in a better position to understand the human influence on global warming in the area."

The scientists analyzed carbon and oxygen isotopes and other elements present in the rock samples through various experiments. They learned that the soil formed at a temperature of 17 degrees Celsius (62.6 degrees Fahrenheit) at the base and 22 degrees Celsius (71.6 degrees Fahrenheit) at the top, a change of 5 degrees Celsius (9 degrees Fahrenheit). They also learned that the paleosol received 222-243 millimeters of precipitation per year during its formation.

Focusing on watersheds, master's student Lupton also has paid close attention to Central Texas geology over the last year. He studies hydrogeology under Alan Dutton, UTSA associate professor of geological sciences and interim chair.

"State programs such as those run by the Texas Water Development Board and national programs, such as those of the U.S. Geological Survey, produce significant amounts of raw data related to geology, geography and hydrology," said Lupton. "Our research centered around processing the raw data with the desired result of creating maps of recharge and discharge zones. Knowing the geographical distribution of recharge and discharge zones affords vested interests the option of whether or not to build sustainably in an area."

For his master's thesis, Lupton merged stream data and water well data using geographic information system (GIS) technology to create a comprehensive map of recharge and discharge zones in the Central Texas Pedernales River Valley.

He focused on the geographical area over the Trinity Hill Country and Llano Uplift aquifers. His maps of recharge and discharge zones maximize the use of sparse data and are anticipated to be a contribution to the study of aquifer interactions in the area.

UTSA's Department of Geological Sciences, housed in the College of Sciences, offers bachelor's and master's programs in geology, a master's program in multidisciplinary studies and a certificate program in geographical information science grounded in research. The department's research facilities include laboratories for biogeochemistry, hydrogeology, engineering geology, isotope geochemistry, micropaleontology and stratigraphy, remote sensing and spatial analysis, and x-ray diffraction.

Learn more at the UTSA Department of Geological Sciences Web site.