Work

Thermodynamic and elastic properties of uvarovite at mantle conditions: Insights from first-principles calculations

Year: 2025

Type: article

Abstract: Uvarovite, an important garnet component in the Earth’s mantle, plays a critical role in interpreting seismic signatures of the deep Earth. In this study, we employed first-principles calculations based on density functional theory (DFT) to examine the thermodynamic and elastic properties of uvarovite under high-pressure and high-temperature conditions (up to 30 GPa and 3000 K). Our results show that elastic moduli and seismic velocities increase with pressure but decrease with temperature and display a slightly nonlinear response. The relatively low AVP of uvarovite suggests that its contribution to the observed seismic anisotropy in the upper mantle is likely negligible. We simulated the variations in density and wave velocity of uvarovite along the geotherm, and investigated the potential geophysical effects of its enrichment in different geological bodies. At depths of 50–250 km, uvarovite exhibits higher density while maintaining shear wave velocities (VS) comparable to the reference model, implying that minor compositional variations may drive density heterogeneities within the subcontinental lithospheric mantle (SCLM) and potentially promote craton delamination. At depths of 250–660 km, uvarovite shows higher density and lower seismic velocities (VP, VS) relative to the upper mantle (UM) and mantle transition zone (MTZ). Our results demonstrate that at 660 km depth, the addition of 20 vol% uvarovite to pyrolite increases density by +4.0%, while reducing compressional wave (VP) and shear wave (VS) velocities by –2.0% to –2.9%. If uvarovite becomes locally enriched in the mantle transition zone, it is likely to generate seismically detectable low-velocity layers, which could significantly influence Earth’s mantle dynamics.

Source: American Mineralogist

DOI: 10.2138/am-2025-9947

Authors: Xu Zheng, Yi Wang, Jiajun Jiang, Feiwu Zhang

Institutions: Chinese Academy of Sciences, Institute of Geochemistry, University of Chinese Academy of Sciences, Ehime University

Language: English

Topic: High-pressure geophysics and materials

Subfield: Geophysics

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: bronze

Funders: National Natural Science Foundation of China, China Postdoctoral Science Foundation, Guizhou Science and Technology Department, National Key Research and Development Program of China

Awards: G2676166339, G3038792932, G3193055971