Collaborative Research: As above so below: Quantifying the role of simultaneous LLSVPs and continents on Earth's cooling history using numerical simulations of mantle convection

地球的冷却速度影响着一个动态的、有生命的世界所必需的许多过程，从板块构造到地球磁场的产生。要了解这些过程的建立、演化和持续运作，需要了解地球的热历史，但这一历史的大部分仍然不受限制，部分原因是一些控制机制尚未量化。因此，该奖项旨在研究地球的冷却速率如何通过行星内部的可变绝缘而改变，这些绝缘由沿着表面的大陆和覆盖外核部分的大型大陆大小的异常材料堆（大型低剪切速度省; LLSVP）组成。以前的研究分别检查了大陆和LLSVP的绝缘效果，但没有集中在潜在的抵消作用的同时绝缘体：大陆被预测为增加地幔的内部温度，而LLSVP降低它。这项研究将量化所产生的动力学和热效应，这些机构和地球的冷却历史，板块构造和磁场的影响。此外，大陆和LLSVP都充当化学库，在地球历史的潜在长时间内将关键元素与参与全球循环隔离开来。然而，LLSVP的形成和演变仍在积极辩论中。这项研究将确定它们可能的热指纹和化学指纹，作为测试其潜在形成时间和持续时间的额外手段。除了科学进步，该项目还将通过跨学科游戏开发计划扩大以地球深处为中心的教育机会，该计划将产生一个新的，广泛分布的，以教育为重点的视频游戏，旨在打击几个地球科学误解，同时支持一个由十名本科生开发人员组成的多元化，跨学科小组。最后，该奖项支持两名研究生和一名博士后学者在两个农村，赠地大学，华盛顿州立大学和爱达荷州大学。该奖项支持一项新的研究，该研究将系统地评估地球地幔（大陆+LLSVP）中同时存在的表面和基底绝缘体如何共同改变地球的热演化和内部地幔动力学。二维球形数值模拟将用于量化模拟LLSVP和大陆材料在增加流变学，热和时间复杂性的模型中的影响，以解决三个研究目标：（1）分离出控制表面相互作用的基本过程（大陆）和基础（LLSVP）绝缘体，（2）量化复杂流变学和内部加热对基础和表面绝缘体对流系统的影响，和（3）检查通过地球的历史时间演变的基础和表面绝缘体的影响。将使用高度并行的有限元代码ASPECT（地球对流问题的高级求解器）对地球地幔进行表面（大陆）和基底（LLSVP）绝缘体的数值模拟。模拟将在爱达荷州大学的Falcon超级计算机（33 k核心，1.17 Petaflop）或华盛顿州立大学的Kamiak高性能计算机集群上的~32-256个计算核心上并行求解。对于约200个计划模拟中的每一个，守恒方程将在约200万个有限元的动态细化网格中离散化，在强热梯度和成分梯度附近具有增强的单元分辨率，该奖项反映了美国国家科学基金会的法定使命，并被认为值得通过使用基金会的智力价值进行评估来支持和更广泛的影响审查标准。

Earth’s cooling rate affects many processes necessary for a dynamic, living world, from plate tectonics to generation of the planet’s magnetic field. Understanding the establishment, evolution, and continued functioning of such processes requires knowledge of the planet’s thermal history, but much of that history remains unconstrained in part because several controlling mechanisms have yet to be quantified. As such, this award aims to study how Earth’s cooling rate may be altered through variable insulation of the planet’s interior by continents along the surface and large, continent-sized piles of anomalous material (Large Low Shear Velocity Provinces; LLSVPs) covering portions of the outer core. Previous studies separately examined the insulating effects of continents and LLSVPs, but none focused on the potentially counteracting effects of simultaneous insulating bodies: continents are predicted to increase the mantle’s internal temperature while LLSVPs decrease it. This study will quantify the resulting dynamic and thermal effects of such bodies and the implications for the Earth’s cooling history, plate tectonics, and magnetic field. Furthermore, both continents and LLSVPs act as chemical reservoirs that isolate critical elements from participating in global cycling for potentially long portions of Earth’s history. However, the formation and evolution of LLSVPs is still actively debated. This study will identify their likely thermal and chemical fingerprints as an additional means of testing their potential formation timing and duration. In addition to scientific advances, this project will expand educational opportunities centered on the deep Earth through an interdisciplinary game development program that will produce a new, widely distributed, educationally focused video game designed to combat several geoscience misconceptions while supporting a diverse, interdisciplinary group of ten undergraduate student developers. Finally, this award supports two graduate students and a post-doctoral scholar at two rural, land-grant universities, Washington State University and University of Idaho. This award supports a novel study that will systematically evaluate how simultaneous surface and basal insulating bodies in Earth’s mantle (continents + LLSVPs) jointly alter the thermal evolution and internal mantle dynamics of the Earth. Two-dimensional spherical numerical simulations will be used to quantify the impacts of simulated LLSVP and continental materials in models of increasing rheological, thermal, and temporal complexity to address three research objectives: (1) isolate the fundamental processes governing interactions of surface (continent) and basal (LLSVP) insulators, (2) quantify the influence of complex rheology and internal heating on the basal and surface insulator convective system, and (3) examine impacts of time-evolving basal and surface insulators through Earth’s history. Numerical simulations of the Earth’s mantle subject to surface (continent) and basal (LLSVP) insulators will be conducted using the highly parallel finite-element code ASPECT (Advanced Solver for Problems in Earth’s ConvecTion). Simulations will be solved in parallel across ~32-256 computational cores on University of Idaho’s Falcon supercomputer (33k cores, 1.17 Petaflop) or Washington State University’s Kamiak high performance computer cluster. For each of the ~200 planned simulations, the conservation equations will be discretized across a dynamically refined grid of ~2 million finite elements with enhanced element resolution near strong thermal and compositional gradients, allowing an accurate quantification of heat transfer through the model system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.