Solid Earth Dynamics

The Large Low Shear Velocity Provinces

What is the present-day physical and chemical state of the solid Earth? How did it dynamically evolve over geological time, leaving behind the geological, geophysical and geochemical signatures across the globe?

My research on solid Earth dynamics focuses on the following aspects:

• Not all hotspots are hot. Data-based interpretation of global volcanism, at hotspots (Bao et al. 2022; Cai et al. In Revision), mid-ocean ridges (Bao et al. 2024; Zhang et al. 2023; Wang et al. submitted) and subduction zones (Li et al. 2023).

An estimate of the global hotspot potential temperature, from Bao et al. (2022)

• Plumes in the lab. Dynamical modeling of mantle plume evolution pathways, source entrainment and surface expressions (Bao and Lithgow-Bertelloni 2024; Bao and Lithgow-Bertelloni Revision Under Review; Bao and Lithgow-Bertelloni Revision Under Review).

Rising lab plumes imaged by bubbles from a rigid half sphere, representing an end-member scenario of the Large Low Shear Velocity Province. From Bao (2024a)

• Mapping the deep mantle. Constraining the distribution of deep mantle heterogeneities and rheological properties (Bao et al. 2026; Bao 2024b). Using a graph-theory framework to trace plausible plume pathways through seismic tomography, and clustering them jointly with lava isotopes, we built the first joint geophysical-geochemical zoning map of the lowermost mantle beneath East Africa and the Indian Ocean, resolving at least three domains within the African LLSVP (Bao et al. 2026).

Seven ways scientists have pictured the deep mantle beneath East Africa and the Indian Ocean, from a single giant plume to many separate sources. Our map tests these ideas against both seismic images and lava chemistry. From Bao et al. (2026)

• Mantle minerals and melts. Structural controls on the properties of mantle minerals and melts, e.g. what makes MgSiO3 liquid resemble its crystalline polymorphs at the atomic scale (Acquadro et al. 2026).

The many forms of MgSiO3, the most abundant mineral in Earth’s mantle, across pressure and temperature. Each box shows how magnesium (orange), silicon (blue) and oxygen (red) are arranged in a crystal, or in the liquid at the top. From Acquadro et al. (2026)

Mantle rocks deform like viscous fluid over geological time-scales.

Related Work

1.

Bao, Xiyuan, Carolina R. Lithgow-Bertelloni, Matthew G Jackson, and Barbara Romanowicz. 2022. “On the relative temperatures of earth’s volcanic hotspots and mid-ocean ridges.” Science 375(6576): 57–61.

2.

Cai, Ronghua, Xiyuan Bao, Stephen F. Foley, Andrea Giuliani, Shihao Jiang, D. Graham Pearson, and Jingao Liu. In Revision. “Evidence for a highly fusible fundamental constituent in the convective mantle.”

3.

Bao, Xiyuan, Tushar Mittal, and Carolina R. Lithgow-Bertelloni. 2024. “Determining mid-ocean ridge geography from upper mantle temperature.” Earth and Planetary Science Letters 641: 118823.

4.

Zhang, Xubo, Eric L. Brown, Jinchang Zhang, Jian Lin, Xiyuan Bao, and William W. Sager. 2023. “Magmatism of shatsky rise controlled by plume-ridge interactions.” Nature Geoscience

5.

Wang, Wei, Xubo Zhang, Feng Xu, Zihua Cheng, Xiyuan Bao, Andreas Stracke, et al. submitted. “Ultra-depleted mantle beneath the marion rise and its implications for ocean rise uplift.”

6.

Li, Shaohua, Jiaqi Li, Thomas P Ferrand, Tong Zhou, Mingda Lv, Ziyi Xi, et al. 2023. “Deep geophysical anomalies beneath the changbaishan volcano.” Journal of Geophysical Research: Solid Earth: e2022JB025671.

7.

Bao, Xiyuan and Carolina R. Lithgow-Bertelloni. 2024. “Self-correction of the optical distortion effect of thermal plumes in particle image velocimetry.” Physics of Fluids

8.

Bao, Xiyuan and Carolina R. Lithgow-Bertelloni. Revision Under Review. “A method for measuring and analyzing four-dimensional flow fields in viscous rayleigh-benard convection.” https://arxiv.org/abs/2609.33036.

9.

Bao, Xiyuan and Carolina R. Lithgow-Bertelloni. Revision Under Review. “Morphology, interactions, and evolution of laminar thermal plumes revealed by four-dimensional velocity measurements and analysis: Application to earth’s mantle.” https://arxiv.org/abs/2609.33042.

10.

Bao, Xiyuan. 2024a. “PhD thesis: Hotspots from top to bottom.” https://escholarship.org/uc/item/4dx424br.

11.

Bao, Xiyuan, Mathurin D. Wamba, and Andreas Stracke. 2026. “A joint geophysical-geochemical deep-mantle zoning map beneath east africa and the indian ocean.” Science 393(6812): 684–689.

12.

Bao, Xiyuan. 2024b. “Giant impact and earth’s mysterious blobs: An interdisciplinary revelation.” Science Bulletin 69(3): 293–294.

13.

Acquadro, Jake, Xiyuan Bao, and Jie Deng. 2026. “Local atomic environments reveal structural controls on MgSiO3 liquid-crystal similarity.” PNAS Nexus: pgag347.