We talk a lot on the show about climate change, especially what we are undergoing now. The activities of humans have definitely had an impact on the current climate situation, but nature likes to have a hand in everything as well. And we’re still learning just how some of the larger processes, like mountain building, affected climate in the past and how they are being affected by climate change today.
In a recent paper in the journal Tectonics, researchers theorized that a feedback loop existed between tectonic deformation and the climate about 13 to 7 million years ago in the North Patagonian Andes of South America. The team conducted field observations, focusing on an area called the “foreland basin”, which is to the east of the Andes and is basically the area behind the mountains that gets pushed back and folded up as the mountains rise.
The Andes began forming when the Nasca plate began to subduct under the South American plate. We talked a few episodes ago about how volcanic arcs form, and the Andes are essentially a volcanic arc formed on land instead of as islands. As these volcanoes grew, they deformed that foreland basin. The largest period of deformation occurred in that 13 to 7 million years ago window and then started to decrease. At that point, glaciation began in the mountains themselves.
Now, with the glaciers eroding away through warmer temps and increased rainfall, and not just due to the current climate change but extending back a couple of million years, the foreland basin deformation has stopped. And fault activity in the mountains has increased. Researchers now have the numbers to confidently say that climate change can actually affect mountain-building processes and not only the other way around.
Friendly reminder that the world is bigger than we sometimes realize and sometimes smaller, and it’s all tied together.
“The Influence of Climate on the Dynamics of Mountain Building Within the Northern Patagonian Andes,” Ezequiel García Morabito et al., 2020 December 25, Tectonics