Integrated Models of Mantle Convection and True Polar Wander, and the Structure of the Earth's Deep Interior

地幔对流和真实极地漂移的综合模型以及地球深层内部结构

• 批准号: 1246670
• 负责人: Bruce Buffett
• 金额: $ 21.45万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246670&HistoricalAwards=false
• 关键词: Integrated; Models; Mantle; Convection; True

The interior of the Earth cools over geological time through the process of thermal convection. Slow creeping flow allows hot material to rise and cold material to sink. This large-scale circulation is responsible for building mountains and driving most of the geological processes we observe at the surface. The Earth also rotates in space, and the orientation of the spin axis evolves slowly with time due to a redistribution of mass associated with thermal convection. Changes in the spin axis, known as true polar wander, are detected in paleomagnetic observations and are attributed to thermal convection. However, it is generally assumed that rotation has little influence on thermal convection. Several new lines of evidence challenge this conventional view. Plate motions are spatially correlated with the orientation of the rotation axis. In addition, the Earth's deep interior has peculiar features that reside on the equator and appear to be affected by rotation. We propose to investigate the dynamic interaction between thermal convection and true polar wander with the aim of better understanding these two fundamental processes.The proposed research will integrate thermal convection and true polar wander into a single, self-consistent description of planetary dynamics. Numerical models of thermal convection are normally based on a set of equations that describe conservation of mass, heat and linear momentum, whereas models of true polar wander are invariably based on conservation of angular momentum. By expanding and generalizing the usual description of thermal convection, we have combined these two processes into a single set of equations that permit full interaction between convection and true polar wander. We plan to solve these equations numerically by adding new capability to an existing community software package called ASPECT, which was developed with support from NSF. All developments undertaken during this project will be made available to the community through the Computational Infrastructure for Geodynamics (www.geodynamics.org). The software will be useful to other researchers for a wide range of potential applications, including the thermal and chemical evolution of continental lithosphere. The proposed research will also contribute to the training of graduate students and young researchers in advanced computational methods.

在热对流过程中，地球的内部在地质时期冷却。缓慢的流动使热材料升起，冷材料下沉。这种大规模的循环量负责建造山脉，并驱动我们在表面上观察到的大多数地质过程。地球也在太空中旋转，由于与热对流相关的质量重新分布，自旋轴的方向随时间缓慢发展。在古磁观测中检测到旋转轴的变化，称为真正的极性徘徊，归因于热对流。但是，通常认为旋转对热对流的影响很小。几条新的证据挑战了这种传统观点。板运动在空间上与旋转轴的方向相关。此外，地球的深层内部具有位于赤道上的特殊特征，并且似乎受旋转影响。我们建议研究热对流和真正的极性徘徊之间的动态相互作用，以更好地理解这两个基本过程。拟议的研究将将热对流和真正的极性徘徊整合为对行星动力学的单一自吻合描述。 热对流的数值模型通常是基于描述质量，热量和线性动量保护的一组方程，而真极徘徊的模型总是基于角动量的保护。 通过扩展和推广热对流的通常描述，我们将这两个过程组合为一组方程，这些方程允许对流和真实极地徘徊之间完全相互作用。我们计划通过将新功能添加到现有社区软件包中，该方程在名为Feact的现有社区软件包中求解，该功能是在NSF的支持下开发的。该项目期间进行的所有发展都将通过地球动力学计算基础设施（www.geodynamics.org）提供给社区。 该软件将对其他研究人员有用，可用于广泛的潜在应用，包括大陆岩石圈的热和化学演化。拟议的研究还将有助于对高级计算方法的研究生和年轻研究人员的培训。