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

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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.