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

从板块构造到地球磁场的产生，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。理解这种过程的建立、演化和持续运作需要了解地球的热历史，但这些历史中的大部分仍然不受限制，部分原因是几种控制机制尚未量化。因此，该奖项旨在研究如何通过沿地表的大陆和覆盖部分外核的大陆大小的大陆大堆异常物质(大型低剪切速度省；LLSVP)对地球内部进行可变绝缘，从而改变地球的冷却速度。以前的研究分别研究了大陆和低地温带的绝缘效果，但没有一项研究集中在同时存在的绝缘体的潜在抵消作用上：据预测，大陆会提高地幔的内部温度，而低地带带会降低地幔的内部温度。这项研究将量化这些天体产生的动力和热效应，以及对地球冷却历史、板块构造和磁场的影响。此外，大陆和LLSVP都作为化学储存库，在地球历史的潜在很长一段时间内，将关键元素与参与全球循环的关键元素隔离开来。然而，LLSVP的形成和演化仍然是一个活跃的争论。这项研究将确定它们可能的热和化学指纹，作为测试它们潜在形成时间和持续时间的另一种手段。除了科学进步，该项目还将通过一个跨学科的游戏开发计划扩大以地球深处为中心的教育机会，该计划将产生一种新的、广泛分布的、以教育为重点的视频游戏，旨在与几个地球科学误解作斗争，同时支持一个由10名本科生组成的多样化的跨学科学生开发小组。最后，该奖项支持华盛顿州立大学和爱达荷大学两所农村大学的两名研究生和一名博士后学者。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底部绝缘体如何共同改变地球的热演化和内部地幔动力学。将使用二维球面数值模拟来量化模拟的LLSVP和大陆材料在流变学、热学和时间复杂性增加的模式中的影响，以满足三个研究目标：(1)分离控制地面(大陆)和基础(LLSVP)绝缘子相互作用的基本过程，(2)量化复杂的流变学和内部加热对基础和表面绝缘子对流系统的影响，以及(3)考察在地球历史上随时间演变的基础和表面绝缘子的影响。将使用高度并行的有限元程序Aspect(地球对流问题高级求解器)对受地表(大陆)和底部(LLSVP)绝缘体影响的地幔进行数值模拟。模拟将在爱达荷大学的猎鹰超级计算机(33K核，1.17Petaflop)或华盛顿州立大学的Kamiak高性能计算机集群上跨~32-256个计算核心并行求解。对于大约200个计划的模拟中的每一个，守恒方程将在由大约200万个有限元组成的动态优化网格上离散，并在接近强烈的热和成分梯度的地方提高单元分辨率，从而允许准确地量化通过模型系统的热传递。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.