(Goinyk Production/Canva)
Antarctica is famous for being a continent buried under ice. But beneath those frozen expanses may lie evidence of mountains that once rivaled today's Himalayas, and which profoundly shaped the trajectory of life on Earth.
Previous work from 2022 has suggested that enormous mountain ranges formed as the supercontinent Gondwana assembled roughly 650 to 450 million years ago.
But a new study adds to the story: It finds that while those mountains have long since eroded away, their buried 'roots' and the sediments they shed may preserve clues to an enormously consequential aspect of their existence.
Researchers think those mountains helped create the environmental conditions that allowed complex animal life to flourish.
This big idea comes from the smallest of geological time capsules: Zircons.
Zircon crystals are unusually durable, and their chemistry and uranium-lead ages can reveal when and where the rocks that produced them formed.
Because more than 99.5 percent of Antarctica is covered by ice, directly sampling its geology is difficult.
Instead, two geologists from the Australian National University looked at zircons carried into ocean sediments from the continent, combining 1,712 newly analyzed grains with thousands of previously studied Antarctic zircons.
Reconstruction of Gondwana highlighting core blocks, interior orogens, and peripheral orogens.
(Chen and Campbell, Earth and Planetary Science Letters, 2026.)
They found that Antarctica has a particularly strong zircon age signature between 650 and 450 million years ago – the period when Gondwana was coming together.
When the Antarctic data were incorporated into a global database and weighted according to the area represented by different samples, the Gondwanan signal became the largest supercontinent-related mountain-building signal in the dataset.
The zircons suggest something much bigger (pun intended) than ancient mountains, though.
Some carry chemical signatures associated with the deep roots of very high mountains – places where rocks were subjected to enormous pressures. These zircons are particularly abundant in the Gondwanan record, supporting the idea that some of the mountain belts were genuinely Himalayan-scale.
The researchers argue that collisions involving what are now known as Antarctica, India, Australia, and the Kalahari produced Himalayan-style ranges.
As these mountains rose, they were simultaneously attacked by the forces of erosion.
That erosion would have dumped enormous quantities of sediment into surrounding oceans, potentially creating "the largest turbidite fan system in the geological record," according to the paper.
Some of the older portion of that fan may itself now be buried beneath the Antarctic ice.
And this is where geology potentially becomes biology.
Eroding mountains don't just produce sand and mud. They release nutrients, including phosphorus and iron, into the oceans. Those nutrients can stimulate primary production by algae and cyanobacteria – the organisms that sit at the bottom of the marine food web and produce oxygen through photosynthesis.
But just creating more oxygen isn't enough – for atmospheric oxygen to rise substantially, organic carbon and other reduced materials need to be buried before they can react with oxygen and return it to the atmosphere.
The Gondwanan mountains may have provided exactly the machinery for doing that. Huge quantities of organic-carbon- and pyrite-rich shale got buried quickly and deeply.
So the sustained nutrient delivery from those eroding mountains helped boost primary production, increasing oxygen production while rapid burial of organic carbon and pyrite prevented some of that oxygen from being consumed again.
That balanced system provided just the right ingredients – oxygen, food, and the chemical building blocks needed for biomineralized skeletons – for animals to rise.
That doesn't mean Antarctic mountains somehow caused the Cambrian explosion (the time in the early Paleozoic during which nearly all animal life originated).
In fact, the authors explicitly stop short of making that claim. Instead, they suggest the mountain building created favorable environmental conditions that helped facilitate the extraordinary diversification of animal life.
There are also important uncertainties.
The timing and magnitude of the rise in atmospheric oxygen aren't as well constrained as the researchers would like; they acknowledge that their oxygen calculations do not prove their hypothesis.
They also note evidence for changes in oxygen-related chemistry as early as around 800 million years ago that their model does not fully explain.
But this new evidence backs up a story that makes sense: Continents collide, mountains rise, mountains erode, nutrients flood the oceans, carbon gets buried – and hundreds of millions of years later, animals diversify into a world that looks increasingly like our own.
And somewhere underneath today's Antarctic ice, the ancient roots of those mountains may still be waiting for us to do more digging.
The Life of Earth
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