Earth owes much of its dynamic surface to its bimodal hypsometry, manifested by high-riding continents and low-riding ocean basins. The thickness of the crust in the lithosphere exerts the dominant control on the long-wavelength elevations of continents. However, there is a limit to how high elevations can rise by crustal thickening. With continuous crustal thickening, the mafic lower crust eventually undergoes a densifying phase transition, arresting further elevation gain—an effect clearly observed in modern orogenic belts. On early Earth, lower crust densification should also limit how high a thickening crust can rise, regardless of the thickening mechanisms. We suggest that lower crust densification combined with a thicker oceanic crust in the Archean may have limited the whole-Earth topographic relief to 3 to 5 kilometers at most—half that of the present day. Unless the oceans were far less voluminous, limited relief would inevitably lead to a water world on early Earth.

中文翻译：

---

早期地球受相位驱动低地壳致密化阻碍的地下地壳出现


地球的动态表面在很大程度上归功于它的双峰螺旋测量，表现为高海拔大陆和低海拔海洋盆地。岩石圈中地壳的厚度对大陆的长波长高程起着主导作用。然而，地壳增厚可以提高海拔高度的程度是有限的。随着地壳的持续增厚，镁铁质下地壳最终发生致密相变，阻止了进一步的海拔上升——这种效应在现代造山带中可以清楚地观察到。在早期的地球上，较低的地壳致密化也应该限制增厚的地壳可以上升多高，而不管增厚机制如何。我们认为，较低的地壳致密化与太古宙较厚的海洋地壳相结合，可能将整个地球的地形起伏限制在最多 3 到 5 公里——现在是现在的一半。除非海洋的体积要小得多，否则有限的缓解将不可避免地导致早期地球上出现水世界。