PDF(Pubmed)
Abstract：
Earth\'s known supercontinents are believed to have formed in vastly different ways, with two endmembers being introversion and extroversion. The former involves the closure of the internal oceans formed during the break-up of the previous supercontinent, whereas the latter involves the closure of the previous external superocean. However, it is unclear what caused such diverging behavior of supercontinent cycles that involved first-order interaction between subducting tectonic plates and the mantle. Here we address this question through 4D geodynamic modeling using realistic tectonic set-ups. Our results show that the strength of the oceanic lithosphere plays a critical role in determining the assembly path of a supercontinent. We found that high oceanic lithospheric strength leads to introversion assembly, whereas lower strength leads to extroversion assembly. A theoretically estimated reduction in oceanic crustal thickness, and thus its strength, during Earth\'s secular cooling indicates that introversion was only possible for the Precambrian time when the oceanic lithosphere was stronger, thus predicting the assembling of the next supercontinent Amasia through the closure of the Pacific Ocean instead of the Indian-Atlantic oceans. Our work provides a new understanding of the secular evolution of plate tectonics and geodynamics as the Earth cooled.
摘要：
地球已知的超级大陆被认为是以截然不同的方式形成的，有两个末端成员是内向和外向。前者涉及关闭在前一个超大陆分裂期间形成的内部海洋，而后者涉及先前外部海洋的封闭。然而,目前尚不清楚是什么原因导致了超大陆周期的这种发散行为，这些行为涉及俯冲构造板块与地幔之间的一阶相互作用。在这里，我们使用现实的构造设置通过4D地球动力学建模来解决这个问题。我们的结果表明，海洋岩石圈的强度在确定超大陆的组装路径中起着至关重要的作用。我们发现高的海洋岩石圈强度会导致内向组装，而较低的强度导致外向组装。理论上估计海洋地壳厚度的减少，因此它的力量，在地球的长期冷却期间，内向型只有在前寒武纪时期才有可能，当时海洋岩石圈更强，从而预测通过关闭太平洋而不是印度洋-大西洋来聚集下一个超大陆阿玛西亚。我们的工作为地球冷却后板块构造和地球动力学的长期演化提供了新的理解。
