Elasticity of davemaoite as a primary contributor to lower-mantle heterogeneities.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41308144.
- Also identified by DOI 10.1126/science.adx8356.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Geophysical detection of subducted mid-ocean ridge basalt (MORB) in the lower mantle is hindered by uncertainties in the elasticity of Fe,Al,Mg,Ti-bearing davemaoite, a key MORB component. Using Brillouin spectroscopy and x-ray diffraction, we determined the elasticity of a Ca<sub>0.906(1)</sub>Fe<sup>2+</sup><sub>0.027(1)</sub>Fe<sup>3+</sup><sub>0.042(1)</sub>Mg<sub>0.033(1)</sub>Al<sub>0.072(1)</sub>Ti<sub>0.020(1)</sub>Si<sub>0.912(1)</sub>O<sub>3</sub> davemaoite up to 113 gigapascals and 2294 K. We found that it exhibited a shear wave velocity 10 to 20% slower than end-member davemaoite, making it the slowest phase among major lower-mantle minerals. Our models show that MORB, containing 20 to 25 volume percent davemaoite, potentially contributes to large low-shear-velocity provinces (LLSVPs), whereas a cumulate layer enriched in davemaoite crystallized from basal magma ocean may comprise ultralow-velocity zones (ULVZs). Davemaoite's ability to host incompatible and heat-producing elements possibly links LLSVPs and ULVZs to mantle plume initiation and geochemical signatures of ocean island basalts.