Studying Detachment: Luc Lavier unearths clues to formation of mountains and oceans
December 14, 2009
As a boy, Luc Lavier grew up in the Burgundy region of France, spending days searching for ammonites among the rocks of ancient oceans and beaches. His explorations sometimes unearthed meter-wide specimens of the fossilized marine shells, so local farmers had to help him remove them.
Lavier has honed his youthful curiosities into an academic career focused on geodynamics, the study of the processes that help shape the formation and structure of continents and oceans. He now holds dual posts at the Jackson School as a research professor in the Institute for Geophysics and an assistant professor in the Department of Geological Sciences.
But Lavier still knows to ask French farmers for help. In 2007, Lavier and Gianreto Manatschal, from the University of Strasbourg, France, were working in the Pyrenees, searching for “detachment faults.” Composed of rocks exhumed from dozens of kilometers deep in the Earth’s crust, the faults provide clues to the formation of mountains and oceans, but the forested terrain offered few outcrops to study. The researchers found what they were looking for one day when they stopped to buy some goat cheese at a farm. The scientists noticed a barn wall consisting of deformed rock with mixed sediment—signs of detachment fault structures. The farmer pointed them to a nearby quarry where they collected samples for their research.
The computer model developed by the scientists based on their findings changed what we know about the formation of the Pyrenees. More broadly, the modeling, published in the journal Nature in 2006, represents a significant step forward in our understanding of the complex formation of oceans and landmasses through rifts and “extreme thinning” of the planet’s crust.
“It’s not a simple physics project,” Lavier says, of computational models based on applied fieldwork. “Once you want to model these processes, you need to develop new numerical techniques.”
Despite his childhood rockhounding, scholastic influences originally directed Lavier away from the geosciences. Since he excelled at math, his teachers in France encouraged him to study the highly theoretical subjects of quantum mechanics and astrophysics as an undergraduate student. As a graduate student in France, he began concentrating on geophysics, working on oil exploration projects. After dealing with equations and numerical analysis for years, the descriptive nature of geosciences forced him to combine critical thinking with analytical modeling.
“I had to learn a lot of geology really fast,” Lavier says. His background served him well, but he also realized that the geosciences require interpretation—and even a little guesswork—compared with the rigid focus of physics.
“You have to have a very broad knowledge base, and it’s hard to do that when you’re very specialized,” Lavier says. “Slowly, you get more than just a descriptive understanding. You get a quantifiable understanding.”
The young fossil hunter had found his adult passion, studying how tectonics and other geologic processes influence the evolution of landmasses and oceans. In 1991, he began attending Columbia University and working at the Lamont-Doherty Earth Observatory. Over nearly a decade, he would earn a second graduate degree and his doctorate, becoming an expert in the field of geodynamics.
For several years, Lavier worked at the California Institute of Technology, developing a three-dimensional model that could simulate tectonic processes and the impacts on plate boundaries. He came to The University of Texas at Austin in 2003 as a researcher with the Institute of Geophysics, and joined the Jackson School’s faculty in 2008.
His work studying detachment faults is a prime example of how he continues to use computational assessments to more accurately assess field observations. Detachment faults allow scientists to look at rocks that correspond with formations that are otherwise underground and difficult to study. In the case of deep-ocean rifts, Lavier and colleagues can find and analyze pieces of the former ocean floor thrusted into the mountains to learn more about their origins and compositions.
“Luckily, some of these pieces are now on top of mountain belts,” Lavier says. “That’s why geology is so important.”
In developing a more detailed picture of past processes and geodynamics, Lavier’s work has several applications. Oil geologists can use models of deep-ocean structures and rifts to guide future energy exploration. Lavier and Manatschal now develop models to describe and predict the geological context of potential oil reserves for areas, such as deep-water ocean basins, which are difficult to access through drilling and testing.
Modeling is also helping to reduce seismic hazards. Lavier is part of TAIGER, an international team of scientists looking at how Taiwan formed—and deformed—to better understand recent earthquake activity. Lavier’s models for the large-scale project help show how geologic history dating back millions of years connects with current seismic rumbles.
At UT Austin, Lavier has teamed with scientists from the Cockrell School of Engineering to create 3-D models that can help show major and minor fault lines and zones, and simulate their strength over time. He is also a board member of the Computational Infrastructure for Geodynamics, a professional group funded by the National Science Foundation, to advance software modeling for geophysics.
And every now and then, he still gets to go home and collect rocks in Burgundy.
by Joshua Zaffos
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