Student explores ancient volcanic flows

Sarah Cronk carries herself with great poise and confidence – for good reason. She already has conducted fieldwork with a well-respected geologist and has experienced the rigors of a research expedition in the Himalayas.Sarah Cronk carries herself with great poise and confidence – for good reason. She already has conducted fieldwork with a well-respected geologist and has experienced the rigors of a research expedition in the Himalayas.

Sarah Cronk is an undergraduate student in ASU’s School of Earth and Space Exploration – and yet if you sat down with her to talk about her radioisotope geochronology research in the San Francisco volcanic field in northern Arizona, you might think she was already a tenured professor.

An earth and space exploration major with a concentration in geology and a student in the Barrett Honors College, Cronk carries herself with great poise and confidence – for good reason. She has already conducted fieldwork with a well-respected geologist and has experienced the rigors of a research expedition in the Himalayas.

“What I'm really interested in is the various radioisotopic dating methods and my project allows me to explore the (U-Th)/He system in depth with a leading expert in the field, professor Hodges,” says Cronk, who will graduate in May 2014.

Over fall break, with the help of Kip Hodges, a professor in the School of Earth and Space Exploration (SESE), and research scientist Matthijs van Soest, Cronk conducted research in northern Arizona. Her project, which is focused on dating ancient basalt volcanic flows, is an offshoot of work that Hodges did in the Taos Plateau volcanic field in New Mexico.

Many attempts have been made at dating the various volcanoes and flows in the San Francisco volcanic field in northern Arizona. Cronk performed her field work near SP crater, whose age estimates are anywhere from several thousand years old to tens of thousands of years old. Cronk and her senior mentors performed the fieldwork together; however, she does much of the lab work on her own, under the tutelage of research staff, postdoctoral associates and graduate students working in Hodges’ lab.

“Absolute dating of young – we are talking Pleistocene – basalt volcanic flows has proved difficult for a variety of factors," Cronk explains. "What I'm doing is exploring a novice method to dating these flows by examining the (U-Th)/He systematics of detrital zircon and apatite in sediments immediately underneath the flow, or the ‘baked zone.’ By performing lab work on sediments I collected, I will isolate zircon and apatite grains and then date them to hopefully get a more secure and competitive age on the young volcanoes there.”

Cronk is completing an honors thesis on the topic of radioisotope geochronology.

“I see Kip several times a week – via one of his courses, a lab meeting and a meeting whenever I need one," she adds. "Considering he was the founding director of the school and his stature in the field of tectonics, Kip is really down to earth. He understands how important it is to influence undergraduates and is always willing to take time from his busy schedule to work with me. Because of him and his team, my research experience has been exceptional and as a result, I have full confidence that I will be prepared for my next academic challenge.”

Cronk’s radioisotope geochronology and thermochronology course, which Hodges teaches, gives her insight on the several methods that are in application in the geosciences today.

“Sarah has proved a real joy for my laboratory colleagues and I to work with,” says Hodges. “Always upbeat, always having fun, but with a real passion for serious science. She’s a role model for us all.”

Nikki Cassis, ncassis@asu.edu
602-710-7169
School of Earth and Space Exploration