University of Rochester

Geologists Awarded $2.5 Million to Explore Relationship Between Ancient Mountain Formation and Climate Change

April 27, 2009

Carmala Garzione, associate professor in the Department of Earth and Environmental Sciences at the University of Rochester, is leading a team of nine scientists from six institutions, who have been awarded $2.5 million from the National Science Foundation to investigate how rising mountain ranges may have altered the global climate.

The project brings together scientists from different disciplines to ultimately understand how certain mountain ranges formed —specifically the Andes of South America. Garzione surprised much of the geological establishment in recent years when she used ancient rainfall measurements to clock the speed of the Andes' formation, and found that the vast mountain range likely experienced a "growth spurt" that pushed it up much faster than geologists had long believed.

As mountains erode, their sediment is carried down their slopes in streams and collects in sedimentary basins within the growing mountain range. As a mountain range rises, it experiences different atmospheric conditions simply due to its change in height. Those atmospheric changes, such as temperature and the composition of rainfall, are recorded in minerals that grow near the surface at different altitudes on the mountainside. Garzione used the age of the sediments and the altitude at which they likely formed to paint a picture of the Andes Mountains rising so quickly that most geological processes could not explain the speed.

Garzione's calculations depend critically on her ability to accurately estimate the weather patterns that the growing range experienced several million years ago. This is complicated by ancient regional and global climate changes, which is why Garzione will be working on the project with Chris Poulsen, an atmospheric scientist from the University of Michigan.

In addition to climate modeling, geophysiscists Susan Beck and George Zandt of the University of Arizona, and Lara Wagner of the University of North Carolina will run a seismic experiment that will enable to team to image the lower crust and mantle beneath the Andes to identify the processes that led to surface uplift. Geochemist, Mihai Ducea of the University of Arizona will analyze volcanic rocks to track the timing of changes in the lithosphere. Brian Horton of the University of Texas at Austin, Nadine McQuarrie of Princeton University, and Todd Ehlers of the University of Michigan will study deformational and erosional histories of the Andes to understand the interplay between crustal thickening and surface uplift processes.

If the continental dynamics project is able to produce a reasonable model of ancient mountain/weather interactions, the team will be able to more accurately describe the rise of the Andes Mountains, and more firmly put in place the theory of the tectonic processes that produced them.