Raising mountains for a habitable Earth

The formation of mountain belts (orogens) elevates rocks above sea level, making them available for chemical weathering and altering the composition of the atmosphere and oceans, which in turn control habitability. Peak-metamorphic pressures recorded by crustal rocks buried in orogens increased between 2.7 to 2.2 and 0.8 to 0.7 billion years ago, indicating that rocks could be buried deeper and that orogens could grow substantially thicker after each of these periods. The two periods of orogenic growth were broadly synchronous with major increases in terrigenous element and nutrient fluxes and changes in biological sulfur metabolism and surface oxygenation. These changes could be explained by enhanced weathering of higher mountains. The findings support the hypothesis that there are first-order mechanistic links between secular geodynamic change and changes in Earth system state and habitability, which shaped the conditions for the evolution of complex life during the past 3 billion years.