Constraining composition and temperature variations in the mantle transition zone.
Wen-Yi Zhou1,2, Ming Hao3,4, Jin S Zhang5,6
1Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, USA. zwy1993@unm.edu.
Nature Communications
|March 2, 2022
Summary
Hydrous wadsleyite properties reveal Earth
Area of Science:
- Earth Sciences
- Mineral Physics
- Geophysics
Background:
- The mantle transition zone (MTZ) is a critical region connecting Earth's upper and lower mantle.
- Wadsleyite is a key mineral within the MTZ, influencing its physical properties.
- Understanding MTZ composition and dynamics is vital for mantle convection and material exchange.
Purpose of the Study:
- To determine the elastic properties of hydrous, iron-bearing wadsleyite under high-pressure and high-temperature conditions.
- To model the global distribution of wadsleyite, temperature, and water content in the MTZ.
- To investigate thermochemical heterogeneities within the MTZ, particularly near subducted slabs and mantle plumes.
Main Methods:
- Single-crystal elastic properties of wadsleyite were measured using Brillouin spectroscopy.
- Mineral physics data were integrated with global seismic observations.
- Geophysical modeling was employed to map MTZ properties.
Main Results:
- High-pressure, high-temperature elastic properties of hydrous Fe-bearing wadsleyite were successfully measured.
- Models indicate colder temperatures, higher wadsleyite proportions, and increased hydration near subducted slabs.
- Regions associated with mantle plumes show distinct characteristics compared to subduction zones.
Conclusions:
- Direct evidence for significant thermochemical heterogeneities in the upper mantle transition zone was provided.
- The findings enhance our understanding of water transport and material cycling between mantle layers.
- This research contributes to a more comprehensive model of Earth's deep interior dynamics.
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