Student travels to Siberia to study earth's climate history

A three-week trip to Siberia was a perfect experience for Aubry DeReuil, who loves traveling, rock climbing and geology.

A junior geology major at Appalachian State University, DeReuil did all three and more as the only undergraduate student working with a team of geologists from 10 countries who were in western China looking for ancient clues related to climate change.

The summer field work was part of a five-year United Nations International Geoscience Programme project being co-led by Dr. Johnny Waters, chairman of Appalachian's Department of Geology.

"The goal of the fieldtrip was to collect fossil and rock specimens of the Devonian age (416 - 360 million years) in Siberia to look for evidence of massive climate change and mass extinction events, which occurred during the Devonian," Waters said. "Because Siberia is largely forested, most outcrops visited by the group were in rock quarries or in cliff exposures along rivers."

DeReuil's undergraduate focus is quantitative geoscience, which combines geology and mathematics. She became interested in geochemistry after reading some research papers on the use of stable isotope analysis and geochemistry to record data about the extinction of marine life that occurred during the late Devonian time period.

"There was a huge extinction event where 50 percent of sea life went extinct, including the disappearance of almost all coral reefs in the Late Devonian. The causes behind this event are not well understood," DeReuil said. "It's a subject a lot of people are trying to figure out, and my project on the isotope stratigraphy in the area will add to the ability to understand what happened and whether or not climate played a role in the extinction globally."

During her trip, DeRuil helped to:

  • Examine exposed rocks in trenches and quarries to search for evidence of ancient marine ecosystems
  • Collect fossils, including ancient marine life known as crinoids, blastoids, ammonoids and brachiopods prevalent along the ancient sea floor
  • Analyze carbon and oxygen isotope levels in rock samples from western China
  • Compare the isotope levels with samples from other field sites to determine if climate change in the region resembles changes in other parts of the world

"The Devonian saw one of the largest changes in carbon dioxide content in the atmosphere in the history of the planet," Waters said. "The Early to Middle Devonian earth had greenhouse atmospheric conditions, which produced large coral reef complexes. Even though Siberia is currently about as far away from an ocean as one can get, these reefs were very well developed there in the Devonian indicating that Siberia had a tropical oceanic environment much like the modern Bahamas or Florida Keys."

Waters said the reefs vanished as part of one of the "Big Five" mass extinction events.

"Coral reef ecosystems did not reappear for more than 50 million years. The disappearance of the reefs was very apparent in the outcrops visited by the group," Waters said.

"Now that I am getting into geochemistry, a new world has opened up to me in terms of future studies," DeReuil said of the experience. "This project is a little piece of a bigger picture regarding understanding earth's history. I realized on this trip that each scientist contributes a tiny part, but when it's all put together it will provide significant answers and of course more questions," she said.

DeReuil said she was excited about the possibility of being able to contribute research to the scientific community. "Now, I know that college can go beyond just doing my schoolwork and getting grades," she said. "This project allows me to discover and contribute to the world of geology, as well as learn as an undergraduate student."