The zircons we studied were depleted in oxygen 18 relative to the mantle, and such depletion occurs only if the crystals formed from rocks that interacted with rain or snow.

• 因为相较于地函，我们所研究的锆石，氧18含量偏低，而这种情形只有可能是晶体的母岩曾经和雨水或雪发生交互作用。