Melting temperatures of MgO under high pressure by micro-texture analysis

• Published in: Nature communications Vol. 8; no. 1; p. 15735
• Main Authors: Kimura, T., Ohfuji, H., Nishi, M., Irifune, T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05-06-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 140/133; 704/2151/2809; 704/2151/431; Behavior; Deformation; Experiments; Humanities and Social Sciences; Lasers; Minerals; multidisciplinary; Rheology; Science; Science (multidisciplinary); Temperature; Japan
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15735

Periclase (MgO) is the second most abundant mineral after bridgmanite in the Earth’s lower mantle, and its melting behaviour under pressure is important to constrain rheological properties and melting behaviours of the lower mantle materials. Significant discrepancies exist between the melting temperatures of MgO determined by laser-heated diamond anvil cell (LHDAC) and those based on dynamic compressions and theoretical predictions. Here we show the melting temperatures in earlier LHDAC experiments are underestimated due to misjudgment of melting, based on micro-texture observations of the quenched samples. The high melting temperatures of MgO suggest that the subducted cold slabs should have higher viscosities than previously thought, suggesting that the inter-connecting textural feature of MgO would not play important roles for the slab stagnation in the lower mantle. The present results also predict that the ultra-deep magmas produced in the lower mantle are peridotitic, which are stabilized near the core–mantle boundary.
Melting behaviour of MgO under pressure remains unclear despite the importance of constraining the rheology and composition of the Earth’s mantle. Here, the authors show that melting temperatures in earlier static experiments were underestimated based on micro-texture analysis of the quenched samples.