Xiyuan Bao’s research has advanced our understanding of the dynamics of mantle plumes in a convection mantle and their surface expression as hot spots. In his 2022 Science paper, he inferred the relative temperature of plumes compared to mid-ocean ridges under 46 oceanic hot spots. He extracted velocity anomalies under the present active location of each hot spot from global tomographic models and under mid-ocean ridges. He corrected the velocities for the effects of damping and converted velocity anomalies to temperature using the self-consistent thermodynamic model HeFESTo. He found that not all hot spots have excess temperatures greater than ridges. At least half of all oceanic hot spots are no more than warm (~100° excess temperature). That is barely hot enough to rise in the convecting mantle without large deflections or losing buoyancy. His results suggested that only very few plumes are hot enough in the upper mantle.

The hottest plumes have the highest ³He/⁴He anomalies indicative of primordial material. For this paper, Xiyuan mastered thermodynamics, geochemistry, geophysics, and machine learning clustering techniques. Using the temperatures inferred under mid-ocean ridges, he later developed a random forest machine learning model to identify the oceanic basin of origin of any mid-ocean ridge segment without prior knowledge of its geographic location. This is possible because the mean temperature of the upper mantle and the difference in temperature between the upper mantle and transition zone uniquely identify a mid-ocean ridge segment and reflect the integrated history of tectonics and convection. This work, soon to be published, opens the door to tectonic reconstructions not only of plates but also of past dynamical states. These advances were only the prelude to the unique experimental work studying the 4D dynamics of plumes in a convecting mantle and their relationship to large low-shear-velocity provinces (LLSVPs). Now in review in the Journal of Fluid Mechanics and presented at the AGU Fall Meeting, his work will show the richness of plume behavior and evolution, including merging, splitting, clustering, detachment, and branching, which might change how we interpret mantle structure in the future.

—Carolina Lithgow-Bertelloni, University of California, Los Angeles

It is with immense gratitude and honor that I accept the Study of the Earth’s Deep Interior Section Award for Graduate Research. I extend my heartfelt thanks to my Ph.D. adviser, Carolina Lithgow-Bertelloni, for her exceptional guidance and her generous nomination. Having Carolina as a mentor during my Ph.D. journey has been an incredible privilege. Her introduction to engaging and enlightening mantle flow experiments, coupled with her encouragement to delve into diverse side projects and to trust in my findings, has been invaluable. Her mentorship led me to revisit classical mantle plume theory and to investigate various types of hot spots. The wisdom I have gained from our discussions, encompassing both research techniques and personal integrity, has been immeasurable. I am also immensely grateful to Matthew Jackson, Lars Stixrude, Jonathan Aurnou, Barbara Romanowicz, Tushar Mittal, Wei Leng, and Lijun Liu, for their unique insights and constructive suggestions to my research, along with their unreserved career advises. Their extensive knowledge and perspective have been a constant source of inspiration. I owe special thanks to Jie Deng, Yufan Xu, Xuesong Ding, Tian Feng, Jiaqi Li, and Yida Li, as well as my groupmates and other colleagues. The daily enriching conversations and their selfless support in both personal and professional areas have been incredibly beneficial. Finally, my heartfelt gratitude goes to my parents and fiancée, whose unwavering love and support have been my anchor. Their belief in me has been my strength in moments of doubt and retreat. This award is a reflection of the collective wisdom, guidance, and support of each one of you. I am grateful and committed to advancing our understanding of Earth’s deep interior with the same passion and integrity that you all have instilled in me. —Xiyuan Bao, University of California, Los Angeles