The Formation and Stabilization of Thickened Lithosphere

加厚岩石圈的形成和稳定

• 批准号: 1112820
• 负责人: Catherine Cooper
• 金额: $ 20.64万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1112820&HistoricalAwards=false
• 关键词: Formation; Stabilization; Thickened; Lithosphere

Continents, covering only ~30% of the Earth's surface, are the sole location of human habitation, yet, unfortunately are also regions of widely distributed deformation resulting in earthquakes, volcanism, landslides, etc. Ultimately, these destructive processes are the consequence of the Earth losing heat that is stored & generated (via decay of radioactive material) within its interior. How this energy translates into the processes that shape the continent's surface still remains an outstanding challenge with great significance for understanding what makes some regions tectonically "safe" versus potentially dangerous. Fortunately, the Earth provides unique insight into its tectonic evolution via areas of the continental interior called cratons. Cratons are thick (~200-300km), old (~3-4 billions of years) regions that have avoided deformation since their origin. Meaning that for the majority of Earth's history while the rest of the Earth's surface was being modified by tectonic processes, cratons resisted being split apart, broken up, compressed or remelted. This longevity and survivability of cratons provides understanding of the driving forces behind deformation over Earth's history. This study aims to increase our understanding of this problem by focusing on mapping out when, how and why thick, stable continental lithosphere forms as well as assessing the future survivability and longevity for current tectonically stable regions of the Earth.This project combines theoretical scalings with two- and three-dimensional time-dependent numerical models to quantitatively determine the dynamic conditions required to thicken and stabilize lithosphere. It will consider two different candidates to make thickened cratonic lithosphere from - buoyant oceanic lithosphere and island arc material. It will also explore the role of a secondary process whereupon the removal of a dense layer (such as eclogite or mafic cumulates) helps promote the stability of cratonic lithosphere. It will compare the generated rheological and composition structure within simulations against seismic observations of the interior of deep cratonic lithosphere. Finally, It will address the size, frequency and nature of drips potentially arising from the base of cratonic lithosphere. By focusing on a critical stage in continental evolution, this work will provide new constraints into the dynamics of the early Earth during which the cores of continental lithosphere were formed.

大陆仅占人类栖息地的唯一位置，但不幸的是，这也是分布广泛变形的区域，导致地震，火山症，滑坡等。最终，这些破坏性过程是在其内部存储和生成泥土材料的碎线的结果。 这种能量如何转化为塑造非洲大陆表面的过程仍然是一个突出的挑战，对于理解使某些地区构造“安全”而不是潜在危险的是什么意义。幸运的是，地球通过称为craton的大陆内部区域对其构造进化提供了独特的见解。 克拉通厚（约200-300公里），旧的（约3-4亿年），自起源以来就避免了变形。 这意味着，在地球的大部分历史中，尽管地球的其余部分正在通过构造过程进行修改，而克拉通则抵制被拆开，分裂，压缩或重新划分。 这种寿命和克拉通的生存能力提供了对地球历史变形背后的驱动力的理解。这项研究的目的是通过专注于绘制何时，如何以及为何构图，如何以及为何构图较厚，稳定的大陆岩石圈形式以及评估地球当前构造稳定稳定区域的未来生存能力和寿命。此项目结合了理论规模与二维时间依赖性的量化，以量化的量化量和三维的量化，以确定量化的量化。它将考虑两种不同的候选者，以使浮力岩石圈增厚 - 浮力岩石圈和岛弧材料。它还将探讨次要过程的作用，因此去除密集层（例如叶绿石或镁铁质累积）有助于促进克拉氏岩岩石圈的稳定性。它将比较模拟中产生的流变和组成结构与深cratonic岩石圈内部的地震观测。最后，它将解决滴水的大小，频率和性质，可能是由克拉通岩石圈底部产生的。通过关注大陆进化中的关键阶段，这项工作将为地球早期的动态提供新的约束，在该动态中形成了大陆岩石圈的核心。