1] Geodynamic Modelling Section, Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany [2] EarthByte Group, School of Geosciences, The University of Sydney, Sydney, New South Wales 2006, Australia.
EarthByte Group, School of Geosciences, The University of Sydney, Sydney, New South Wales 2006, Australia.
Nat Commun. 2014 Jun 6;5:4014. doi: 10.1038/ncomms5014.
When continents break apart, continental crust and lithosphere are thinned until break-up is achieved and an oceanic basin is formed. The most remarkable and least understood structures associated with this process are up to 200 km wide areas of hyper-extended continental crust, which are partitioned between conjugate margins with pronounced asymmetry. Here we show, using high-resolution thermo-mechanical modelling, that hyper-extended crust and margin asymmetry are produced by steady state rift migration. We demonstrate that rift migration is accomplished by sequential, oceanward-younging, upper crustal faults, and is balanced through lower crustal flow. Constraining our model with a new South Atlantic plate reconstruction, we demonstrate that larger extension velocities may account for southward increasing width and asymmetry of these conjugate magma-poor margins. Our model challenges conventional ideas of rifted margin evolution, as it implies that during rift migration large amounts of material are transferred from one side of the rift zone to the other.
当大陆分裂时，大陆地壳和岩石圈会变薄，直到分裂完成并形成一个海洋盆地。与这个过程相关的最显著和最不为人理解的结构是宽达 200 公里的超伸展大陆地壳区域，这些区域被共轭边缘之间的明显不对称性分割开来。在这里，我们使用高分辨率的热-力学模拟表明，超伸展地壳和边缘不对称性是由稳定的裂谷迁移产生的。我们证明裂谷迁移是通过顺序的、向海洋年轻的上地壳断层来实现的，并且通过下地壳流动来平衡。通过对新的南大西洋板块重建的约束，我们表明更大的伸展速度可能解释了这些共轭贫岩浆边缘向南宽度和不对称性的增加。我们的模型挑战了裂谷边缘演化的传统观念，因为它意味着在裂谷迁移过程中，大量物质从裂谷带的一侧转移到另一侧。
