New research using zircon crystals from Antarctic sediments suggests that mountain belts as large as the Himalayas formed during the assembly of Gondwana between 650 and 450 million years ago. The study, published in Earth and Planetary Science Letters, argues that rapid erosion of those ranges carried carbon-rich mud into deep ocean basins, where it was buried before it could decay. That burial may have reduced oxygen consumption enough to help create conditions for the Cambrian explosion of animal life. Geologists analyzed thousands of detrital zircons and found chemical fingerprints that only form under the extreme pressure of high mountain roots. They estimate the eroded sediment fan held more than 3.6 x 10^20 kilograms of sediment. The authors stress the oxygen calculation is uncertain, but the scale is large enough to make the mechanism plausible. The study adds to a growing picture of how deep-time tectonics and the carbon cycle shaped life on Earth.
