英国南安普顿大学Gernon, Thomas M.研究团队最新的研究揭示了大陆裂解期间克拉通边缘和内部共同演化。2024年8月7日出版的《自然》杂志发表了这项成果。

在这里，研究人员将地质观测、统计分析、地球动力学模拟和景观演化模型结合起来，建立了一个物理模型，将这两种现象与大陆裂谷机制联系起来。悬崖主要起源于裂谷边缘的断层，并在约1kmMyr^-1处通过向上游侵蚀缓慢后退。与此同时，裂谷作用在地幔中产生对流不稳定，这些对流不稳定沿着岩石圈根部以更快的速度向克拉通方向迁移，速度约为15-20kmMyr^-1，逐渐移除克拉通龙骨，驱动克拉通内部均衡隆起，形成稳定的、升高的高原。

这一过程迫使同步的剥蚀浪潮，被记录在热年代学研究中，持续数千万年，并以相当或较慢的速度在克拉通中迁移。研究人员将观测到的裂谷、悬崖形成和克拉通内部折返的序列解释为与大陆分裂相关的地球动力学地幔过程的演化记录，颠覆了克拉通作为地质稳定地形的流行概念。

据悉，在冈瓦纳大陆断裂和分裂期间分散的许多克拉通大陆碎片被称为“大悬崖”的陡峭地形所束缚，其边缘是克拉通内部隆起的高原。就形成而言，断崖和高原——由于它们的空间分离，它们传统上被认为是不同的，有时跨越超过一千公里。

附：英文原文

Title: Coevolution of craton margins and interiors during continental break-up

Author: Gernon, Thomas M., Hincks, Thea K., Brune, Sascha, Braun, Jean, Jones, Stephen M., Keir, Derek, Cunningham, Alice, Glerum, Anne

Issue&Volume: 2024-08-07

Abstract: Many cratonic continental fragments dispersed during the rifting and break-up of Gondwana are bound by steep topographic landforms known as ‘great escarpments’, which rim elevated plateaus in the craton interior. In terms of formation, escarpments and plateaus are traditionally considered distinct owing to their spatial separation, occasionally spanning more than a thousand kilometres. Here we integrate geological observations, statistical analysis, geodynamic simulations and landscape-evolution models to develop a physical model that mechanistically links both phenomena to continental rifting. Escarpments primarily initiate at rift-border faults and slowly retreat at about 1kmMyr^-1 through headward erosion. Simultaneously, rifting generates convective instabilities in the mantle that migrate cratonward at a faster rate of about 15–20kmMyr^-1 along the lithospheric root, progressively removing cratonic keels, driving isostatic uplift of craton interiors and forming a stable, elevated plateau. This process forces a synchronized wave of denudation, documented in thermochronology studies, which persists for tens of millions of years and migrates across the craton at a comparable or slower pace. We interpret the observed sequence of rifting, escarpment formation and exhumation of craton interiors as an evolving record of geodynamic mantle processes tied to continental break-up, upending the prevailing notion of cratons as geologically stable terrains.

DOI: 10.1038/s41586-024-07717-1

Source: https://www.nature.com/articles/s41586-024-07717-1