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.

大陆仅覆盖地球表面约 30%，是人类居住的唯一地点，但不幸的是，大陆也是广泛分布的变形区域，导致地震、火山活动、山体滑坡等。归根结底，这些破坏过程是人类居住的结果。地球失去其内部储存和产生的热量（通过放射性物质的衰变）。 这种能量如何转化为塑造大陆表面的过程仍然是一个突出的挑战，对于理解是什么使某些地区在构造上“安全”而不是潜在危险具有重要意义。幸运的是，地球通过称为克拉通的大陆内部区域提供了对其构造演化的独特见解。 克拉通是厚（约 200-300 公里）、古老（约 3-40 亿年）的区域，自诞生以来就避免了变形。 这意味着，在地球历史的大部分时间里，虽然地球表面的其余部分正在被构造过程所改变，但克拉通却抵抗着分裂、破碎、压缩或重熔。 克拉通的这种长寿和生存能力让我们了解了地球历史上变形背后的驱动力。这项研究旨在通过重点绘制厚而稳定的大陆岩石圈形成的时间、方式和原因，以及评估地球当前构造稳定区域的未来生存能力和寿命，来加深我们对这个问题的理解。该项目将理论尺度与二维和三维与时间相关的数值模型，用于定量确定岩石圈增厚和稳定所需的动态条件。它将考虑两种不同的候选材料来制造增厚的克拉通岩石圈——浮力海洋岩石圈和岛弧材料。它还将探讨二次过程的作用，其中致密层（例如榴辉岩或镁铁质堆积物）的去除有助于促进克拉通岩石圈的稳定性。它将模拟中生成的流变和成分结构与深层克拉通岩石圈内部的地震观测进行比较。最后，它将解决克拉通岩石圈底部可能产生的滴水的大小、频率和性质。通过关注大陆演化的关键阶段，这项工作将为形成大陆岩石圈核心的早期地球动力学提供新的约束。