Peter DeCelles Receives Lifetime Achievement Award from Geological Society of America

DeCelles' research focuses on the origins of major mountain ranges all over the world and the evolution of the sedimentary basins that form alongside them.

Peter DeCelles, a professor of geosciences at The University of Arizona in Tucson, has been awarded the Laurence L. Sloss Award by the Geological Society of America.

This award is given to "a sedimentary geologist whose achievements contribute widely to the field of sedimentary geology and through service to GSA," according to the society. The Sloss Award is given annually to recognize the lifetime achievements of one sedimentary geologist.

"It's neat to have some recognition for things that one spends a long time doing," DeCelles said. "To receive an award like that is a strong validation of what you've been doing. It's pretty gratifying."

The award will be presented Saturday in Houston at the GSA's annual meeting.

Karl Flessa, head of the UA's department of geosciences, wrote in an e-mail, "The Sloss Award is recognition of Pete's research accomplishments and evidence of Pete's prominent standing in the geological community."

DeCelles credits some of his success to having good colleagues at the UA.

"Almost all of my work has involved strong collaborations, and I have benefited enormously from the collegiality and willingness of my students and colleagues to engage in multi-disciplinary studies," DeCelles wrote in an e-mail.

His research focuses on the origins of major mountain ranges all over the world and the evolution of the sedimentary basins that form alongside them. His studies include the Himalayas, the Rocky Mountains, the Andes and the Apennines.

DeCelles studies how mountain ranges are formed by plate tectonics. The processes include giant pieces of the earth's crust colliding into each other, sliding past each other and plunging beneath each other.

As one plate dives beneath the other, the top plate scrapes sediment from the bottom plate into a huge pile, creating a mountain range. The piles of rock at the foot of the mountains are so heavy, the bottom plate flexes downward. Sediment accumulates in the resulting basin, hence the term sedimentary basin.

Flessa wrote in an e-mail, "Pete is extraordinarily skilled at reading the tectonic message contained in sedimentary rocks."

DeCelles uses structural geology and geological mapping to explain how mountain ranges and their basins developed. He takes rock and sediment samples from mountain tops and sedimentary basins to figure out the ages of the rocks and the time that certain geological processes happened. 

For almost 15 years, DeCelles has conducted field work on treks that can last up to six weeks in the roadless areas of the Himalayas in Nepal.  

The steep inclines, landslides and avalanches make it extremely difficult to navigate the mountains. He said the monsoons from the Bay of Bengal "fire-hose" the mountain range, creating large, deep canyons and "gnarly, Wizard-of-Oz-type peaks."

"It's completely off the charts compared to any other mountain range on earth," DeCelles said. "Things like the Alps or Rockies, they're nothing. The Himalayas are so incredible, and there's so many big questions, and the processes are huge."

Rocks that originate at greater depths have been exposed to more heat and pressure and therefore record more processes, he said.

Rocks at the surface of the Himalayas come from depths of 35 km (about 22 miles) below the surface, compared with rocks at the surface of the Andes that come from 10 km (about 6 miles) deep.

Although the Sloss Award recognizes lifetime achievement, DeCelles has no plans to stop doing research.

"It's nice recognition," he said. "I take it as a sign to keep doing what I'm doing."

DeCelles received his bachelor's degree in geology from the University of Notre Dame in Indiana in 1980. He earned his master's and his doctorate in geology from Indiana University in Bloomington in 1984. He was a postdoctoral scholar at Stanford University from 1984-1986. 

From 1986-1992, he was an assistant professor at the University of Rochester and became an associate professor there in 1992. He joined the UA in 1993 as an associate professor and was promoted to professor in 1998.

DeCelles was a National Science Foundation-NATO Fellow at the University of Bologna in Italy 1990-1991; a visiting professor at the University of Rome for part of 1996; a guest professor at the University of Bologna for part of 2007; and the Allan Cox Professor at Stanford University in 2007-2008.

He has been the editor of both Basin Research and the Journal of the Nepal Geological Society. He is a fellow of the Geological Society of America and of the Explorers Club, and a member of the American Geophysical Union and the Arizona Geological Society.

DeCelles teaches a range of undergraduate and graduate geosciences courses. He has published six guidebooks about sedimentation, rock structure and plate tectonics in various mountain ranges and more than 90 peer-reviewed research articles.