In the high Andes region of South America lies the Altiplano-Puna plateau, a harsh, windswept terrain reminiscent of another world. Second only to Tibet in altitude and volcanism, this elevated landmass features peaks that nearly touch the sky. Previously, scientists believed the mountains formed solely from plate tectonics, where surfaces were pushed up through scraping and shortening. However, a significant discovery lies about ten miles underground.
Massive Magma Reservoir Discovered
In the middle crust of the central Andes, an extensive molten magma reservoir known as the Altiplano-Puna Magma Body exists. This active magma reservoir is the largest imaged on Earth, spanning approximately 125 miles wide. It supplies a whole chain of volcanoes, but its most shocking aspect is its ability to expand.
The Breathing Mountain Dome
Studying the effects of this magma chamber revealed a regional uplift forming a new mountain dome. A study in Nature Communications linked magma accumulation to the uplift. Scientists examining gravity anomalies and crustal deformation found that continuous magma intrusion contributes to plateau uplift. This challenges the traditional view that only tectonic plate collisions raise mountains. The 'breathing mountain dome' phenomenon highlights a powerful underground engine reshaping our understanding of mountain formation.
Mapping the Invisible
Since no technology can see ten miles underground, seismology mapped the magma accumulation using seismic 'pings' and gravity anomalies. Researchers discovered a large zone of low velocity, where seismic waves slowed down due to hot, viscous rocks. This data revealed a massive flat magma accumulation, described as a sill. The study titled Sombrero Uplift Above the Altiplano-Puna Magma Body explains this as a 'ballooning' process, where the mid-crust acts like a large-scale pump. As more melt enters, the crust pushes upward in a sombrero-like manner, demonstrating an invisible force shaping our reality.
This discovery underscores how much remains unknown about Earth's inner workings. While we admire mountain ranges, we only see the roof of an underground factory working tirelessly to raise the horizon.
