早期地球构造由月球潮汐退却期间地球形状变化驱动
Tectonics on early Earth driven by Earth's changing shape during tidal recession of the Moon
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中文总结 AI 辅助
本研究探讨月球潮汐退却导致地球自转减速及形状变化，驱动早期地壳构造运动，解释岩石多样性起源。
中文摘要 AI 辅助
地球上最早期地壳的碎片鲜有存留，因此我们星球历史上这一形成时期笼罩在神秘之中。为了利用有限的数据，理解所有可能塑造我们年轻星球的过程至关重要。在此，我探索了早期地球动力学中一个先前被忽视的方面：自转。月球形成撞击后的地球快速自转，在撞击后的最初数千万年间，随着月球潮汐退却，其自转速率显著减慢。利用行星结构和潮汐演化计算，我表明地球初始的扭曲结构很可能导致了原始地壳厚度显著的纬度变化。此外，随后地球形状对其自转速率减慢的响应可能驱动了广泛的构造活动，并调节了地壳对其他力的响应。在高角动量情景下，极地地区地壳发生伸展，赤道地区发生汇聚，其速率可能堪比今天形成喜马拉雅山的速率。取决于最早期地壳的流变学，这种运动可能导致水合和风化地表物质的埋藏、广泛的火山活动以及地球内部的脱气。由于内部压力增加引起的相变可能导致部分地壳的拆沉，产生早期地幔的不均一性。地壳的水合二次熔融以及演化岩浆的产生可以解释在地球形成后数千万年内岩石类型多样性的出现。
英文摘要
Few fragments of Earth's earliest crust have survived, and so this formative period of our planet's history is shrouded in mystery. To leverage the limited data available, it is important to understand all the processes that could have shaped our young planet. Here, I explore a previously neglected aspect of early-Earth dynamics: rotation. Earth after the Moon-forming impact was rapidly rotating with its rotation rate slowing significantly during the first tens of millions of years after the impact as the Moon tidally receded. Using planetary structure and tidal evolution calculations, I show that the initially distorted structure of Earth would likely have led to significant latitudinal variations in primary crustal thickness. Further, the subsequent changes in Earth's shape in response to its slowing rotation rate could have driven extensive tectonic activity and modulated the response of the crust to other forces. There was extension of the crust in polar regions and convergence in the equatorial regions at rates potentially comparable to those forming the Himalayas today in high-angular momentum scenarios. Depending on the rheology of the earliest crust, such motions could have led to burial of hydrated and weathered surface material, extensive volcanism, and degassing of Earth's interior. Phase changes due to increases in internal pressure could have led to delamination of parts of the crust, producing early mantle heterogeneities. Hydrated secondary melting of the crust and the production of evolved magmas could explain the emergence of a diversity of rock types within tens of millions of years of Earth's formation.
发表机构
- University of Bristol（布里斯托大学）
- California Institute of Technology（加州理工学院）
机构由 AI 辅助整理，请以论文原文为准。
