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Weak cubic CaSiO₃ perovskite in the Earth's mantle

Title data

Immoor, Julia ; Miyagi, L. ; Liermann, H.-P. ; Speziale, S. ; Schulze, K. ; Buchen, Johannes ; Kurnosov, Alexander ; Marquardt, Hauke:
Weak cubic CaSiO₃ perovskite in the Earth's mantle.
In: Nature. Vol. 603 (2022) . - pp. 276-279.
ISSN 1476-4687
DOI: https://doi.org/10.1038/s41586-021-04378-2

Abstract in another language

Cubic CaSiO3 perovskite is a major phase in subducted oceanic crust, where it forms at a depth of about 550 kilometres from majoritic garnet. However, its rheological properties at temperatures and pressures typical of the lower mantle are poorly known. Here we measured the plastic strength of cubic CaSiO3 perovskite at pressure and temperature conditions typical for a subducting slab up to a depth of about 1,200 kilometres. In contrast to tetragonal CaSiO3, previously investigated at room temperature, we find that cubic CaSiO3 perovskite is a comparably weak phase at the temperatures of the lower mantle. We find that its strength and viscosity are substantially lower than that of bridgmanite and ferropericlase, possibly making cubic CaSiO3 perovskite the weakest lower-mantle phase. Our findings suggest that cubic CaSiO3 perovskite governs the dynamics of subducting slabs. Weak CaSiO3 perovskite further provides a mechanism to separate subducted oceanic crust from the underlying mantle. Depending on the depth of the separation, basaltic crust could accumulate at the boundary between the upper and lower mantle, where cubic CaSiO3 perovskite may contribute to the seismically observed regions of low shear-wave velocities in the uppermost lower mantle, or sink to the core–mantle boundary and explain the seismic anomalies associated with large low-shear-velocity provinces beneath Africa and the Pacific.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Research Institutions > Research Centres > Bavarian Research Institute of Experimental Geochemistry and Geophysics - BGI
Graduate Schools > Bayreuth Graduate School of Mathematical and Natural Sciences (BayNAT)
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 510 Mathematics
Date Deposited: 11 May 2022 08:18
Last Modified: 11 May 2022 08:18
URI: https://eref.uni-bayreuth.de/id/eprint/69591