据研究人员介绍，地球的动态表面在很大程度上要归功于它的双模态高度，表现为高海拔的大陆和低海拔的海洋盆地。岩石圈中地壳的厚度对大陆的波长高度起着主要的控制作用。然而，由于地壳增厚，海拔上升的高度是有限的。
研究人员称，随着地壳的不断增厚，基性下花岗岩最终经历了致密化相变，阻止了海拔的进一步抬升—这一效应在现代造山带中可以清晰地被观察到。在早期地球上，无论增厚机制如何，较低的地壳密度也应该限制了增厚地壳可以上升的高度。
研究人员认为，太古代较低的地壳密度加上较厚的海洋地壳可能将整个地球的地形起伏限制在3至5公里，最多为现在的一半。除非海洋的体积比它们小得多，否则有限的缓解将不可避免地导致早期地球上出现一个水世界。
附：英文原文
Title: Subaerial crust emergence hindered by phase-driven lower crust densification on early Earth
Author: Ming Tang, Hao Chen, Cin-Ty A. Lee, Wenrong Cao
Issue&Volume: 2024-09-13
Abstract: 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.
DOI: adq1952
Source: https://www.science.org/doi/10.1126/sciadv.adq1952