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Dr. J. Brian Mahoney receives NSF grant to study Andes Mountains

October 29, 2013
Andes-web
Geology students (left to right) Ellen Buelow, Brian Nehring and Samantha Taylor study rock formations in the Andes Mountains in Mendoza, Argentina, as part of NSF- funded research.

EAU CLAIRE — Dr. J. Brian Mahoney, professor of geology at the University of Wisconsin-Eau Claire, recently received a three-year $224,916 grant from the National Science Foundation to continue a faculty-student collaborative research project in the South Central Andes Mountains located in Mendoza, Argentina.

The purpose of the project is to study the origin and evolution of the modern Andes by examining the structural geology and sedimentary record to determine the rate and style of uplift of the mountain range.

Geology students Samantha Taylor, a senior from Roscoe, Ill., Ellen Buelow, a senior from Chilton, and Chaz McCann, a junior from Amery, currently are the student researchers working with Mahoney on the project. Senior Brian Nehring, a geology major from Hopedale, Mass., participated in the project over the summer. Taylor, Buelow and McCann will be heavily involved in all aspects of field and laboratory analyses going forward, and will participate in stratigraphic studies, sedimentary petrology, geochemistry and isotopic analyses at UW-Eau Claire and the University of Arizona.

The research also is being conducted in collaboration with San Diego State University, Syracuse University and the University of Arizona, as well as two ongoing international, multidisciplinary investigations, including an ongoing three-year United Nations Educational, Scientific and Cultural Organization (UNESCO) International Geoscience Programme investigation, and a project supported by the federal Argentina funding program. Mahoney and his team of student researchers will work in the field alongside geologists from Argentina, Chile, France and the United States.

Preliminary studies revealed that the mountain range is still growing, and uplifting is occurring faster than previously thought, which means the range is much younger than has been predicted, Mahoney said.

"The modern Andean system was previously predicted to be 15 million years old, but is actually closer to 8 million years old," Mahoney said. "Things are happening rapidly and the rate and magnitude of fault displacements are much higher. This has significant implications for earthquake and volcanic studies."

Taylor, Buelow and Nehring accompanied Mahoney to Mendoza in August where they spent three weeks exploring a variety of basins and uplifts in the Andes searching for volcanic rocks and ash beds. The students used stratigraphy, the branch of geology that studies rock layers and layering, to collect samples and shipped them back to UW-Eau Claire for further study.

"We shipped approximately 220 pounds of rock formations back to Eau Claire," Taylor said. "We had to be really careful when packing them up to prevent contamination across samples. Once we returned, Ellen and I started working with Chaz to break down the rocks into a fine sand to extract a mineral called zircon."

Mahoney explained that zircon is a mineral that occurs in trace amounts in many rocks in the Earth's crust and is utilized to provide critical age constraints on geologic processes. It is a durable, resistant mineral that crystallizes from molten magma, survives metamorphic heat and pressure, and is not damaged by surficial weathering and erosion. Zircon contains a tiny amount of uranium, an unstable radiogenic element that decays through time to form the stable element lead. Geologists make precise measurements of the uranium-lead ratio, and are able to calculate an age for the zircon crystal based on a known decay rate. Mahoney and his students will date zircon from sedimentary rocks that have eroded from the Andes over the past 10-20 million years, which will allow them to constrain how source areas have changed and how the mountains have evolved through time.

"After the zircon is extracted, we mount them in epoxy and polish them," Taylor said. "Once all of the samples are finished, we will take them to the University of Arizona's geochronology lab where we will analyze them by hitting each zircon with a high-energy laser and precisely measuring the isotopic composition in an inductively coupled plasma mass spectrometer to determine the age of the rocks."

The zircon extraction process will be passed down solely to McCann, the newest researcher on the team, after Taylor and Buelow graduate in December. He said he is ready to accept the responsibility and is looking forward to accompanying Mahoney on the next trip to Mendoza.

"This is an amazing opportunity to learn about geology outside of the classroom and get hands-on experience performing geologic techniques in the field," McCann said. "It is exciting and a bit overwhelming that I will be conducting research with professionals in the geology field. I am honored to be a part of this project and am prepared to do my best. I am looking forward to working with Dr. Mahoney and to learn as much as possible from him."

Taylor and Buelow said they benefited greatly from the field experience and from surrounding themselves in the Argentinian culture.

"Watching the professionals from different cultures interact in the field was one of the most interesting parts of the experience for me," Buelow said. "They were able to overcome language and cultural differences to work out geologic issues. Geology really is the same in any culture, but the approach and attitude is different. The geologists from Argentina and Chile started each day by sharing a traditional tea (mate) with everyone as they headed out to the field. It encouraged relationship building and set the tone for participation among everyone. They were also very excited to teach us and spent time answering our questions, which I thought was great."

For Taylor, the most memorable part of the research experience in Mendoza was visiting the National Scientific and Technical Research Council (CONICET), an Argentine government agency which directs and coordinates most of the scientific and technical research done in universities and institutes.

"Meeting geologists from other cultures and countries and being able to visit CONICET was an incredible experience," Taylor said. "This was only my second time out of the country and to have this international research project on my resume will benefit me anywhere I decide to go after I graduate from UW-Eau Claire. It shows I have experience in the field and have organizational and leadership skills. This type of experience exposes you to different things you wouldn't do in a classroom setting. You learn more detailed aspects of geology by conducting research."

Buelow said she developed many skills from participating in the research project on the Andes Mountains and from observing how Mahoney and other professionals worked in the field.

"I learned organizational, time management and communication skills that are necessary for performing accurate field research," Buelow said. "We also had practice working with people under what can be stressful situations."

Buelow said she is considering applying to graduate school in the area of sedimentology after she graduates. Taylor also said she is interested in going to graduate school but would like to gain some job experience doing geologic consulting before applying.

The Andes Mountains research project developed out of the 2011 TIES (Thematic Interdisciplinary Experiential Semester) program in which students and faculty across different disciplines traveled to Mendoza as part of an immersion trip to provide students with a living-learning experience. Students learned from UW-Eau Claire faculty in geology, biology and economics, as well as from a local expert in Latin American studies and the Argentine people.

"This is a scientific project that grew out of a university sponsored program and allows our students the experience of collaborating with international scientists and foreign governments," Mahoney said. "It is a great example of how our connections and programs work to provide exciting and educational opportunities for our students."

For more information about the Andes Mountains research, contact Dr. J. Brian Mahoney at mahonej@uwec.edu or 715-836-4950.

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