Deformation Features of Super-Deep Diamonds

• Published in: Minerals
• Main Authors: Alexey Ragozin, Dmitry Zedgenizov, Vladislav Shatsky, Konstantin Kuper, Hiroyuki Kagi
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: diamond; internal structure; electron backscatter diffraction; deformation; Mineralogy; QE351-399.2; Yakutia
• Online Access: https://doi.org/10.3390/min10010018; https://doaj.org/article/9ae1e3f1d5594c35aa8dea4c22402f8a

The paper presents new data on the internal structure of super-deep (sublithospheric) diamonds from Saõ-Luiz river placers (Brazil) and from alluvial placers of the northeastern Siberian platform (Yakutia). The sublithospheric origin of these diamonds is supported by the presence of mineral inclusions corresponding to associations of the transition zone and lower mantle. The features of morphology and internal structure have been studied by optical and scanning electron microscopy (SEM), cathodoluminescence topography (CL), and electron backscatter diffraction (EBSD) techniques. Diamonds typically have complicated growth histories displaying alternating episodes of growth, dissolution, and post-growth deformation and crushing processes. Most crystals have endured both plastic and brittle deformation during the growth history. Abundant deformation and resorption/growth features suggest a highly dynamic growth environment for super-deep diamonds. High temperatures expected in the transition zone and lower mantle could explain the plastic deformations of super-deep diamonds with low nitrogen content.