| Инд. авторы: | Chepurov A., Sonin V., Dereppe J.-M., Zhimulev E.I., Chepurov A. |
| Заглавие: | How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology |
| Библ. ссылка: | Chepurov A., Sonin V., Dereppe J.-M., Zhimulev E.I., Chepurov A. How do diamonds grow in metal melt together with silicate minerals? An experimental study of diamond morphology // European Journal of Mineralogy. - 2020. - Vol.32. - Iss. 1. - P.41-55. - ISSN 0935-1221. - EISSN 1617-4011. |
| Внешние системы: | DOI: 10.5194/ejm-32-41-2020; РИНЦ: 43232868; SCOPUS: 2-s2.0-85078315520; WoS: 000508178000001; |
| Реферат: | eng: The origin and evolution of metal melts in the Earth's mantle and their role in the formation of diamond are the subject of active discussion. It is widely accepted that portions of metal melts in the form of pockets can be a suitable medium for diamond growth. This raises questions about the role of silicate minerals that form the walls of these pockets and are present in the volume of the metal melt during the growth of diamonds. The aim of the present work was to study the crystallization of diamond in a complex heterogeneous system: Metal-melt-basalt-carbon. The experiments were performed using a multianvil high-pressure apparatus of split-sphere type (BARS) at a pressure of 5.5 GPa and a temperature of 1500 °C. The results demonstrated crystallization of diamond in metal melt together with garnet and clinopyroxene, whose chemical compositions are similar to those of eclogitic inclusions in natural diamond. We show that the presence of silicates in the crystallization medium does not reduce the chemical ability of metal melts to catalyze the conversion of graphite into diamond, and, morphologically, diamond crystallizes mainly in the form of a cuboctahedron. When the content of the silicate material in the system exceeds 5 wt %, diamond forms parallel-growth aggregates, but 15 wt% of silicate phases block the crystallization chamber, preventing the penetration of metallic melt into them, thus interrupting the growth of diamond. We infer that the studied mechanism of diamond crystallization can occur at lower-mantle conditions but could also have taken place in the ancient continental mantle of the Earth, under reducing conditions that allowed the stability of Fe-Ni melts. © Author(s) 2020.
|
| Ключевые слова: | high pressure; experimental study; silicate melt; diamond; crystallization; experimental mineralogy; phase transition; |
| Издано: | 2020 |
| Физ. характеристика: | с.41-55 |