RUSSIAN JOURNAL OF EARTH SCIENCES, VOL. 19, ES5006, doi:10.2205/2019ES000677, 2019
A. G. Simakin
Various geodynamic mechanisms can lead to the penetration of siliceous carbonates into the mantle wedge. Their thermal decomposition in the "mantle olivine autoclave" can be a mechanism for the formation of diamond erupted in subduction zone of Kamchatka. Using the theory of poroelasticity, we showed that rapid heating of a mixture of sideritic dolomite and silica on 150–200° C in the closed system conditions can temporarily lead to an increase in the fluid pressure by 2–3 GPa. With the initial parameters $P = 2$ GPa and $T = 830$° C, the carbonic fluid produced during the reaction would get into the PT stability field of the diamond. The growth of diamond at the fluid decomposition in the PT field of metastable graphite can be enhanced by microparticles of native Ni and Mn formed by the thermal decomposition of gaseous metals carbonyls. The corresponding abundant micro-inclusions of Ni and Mn were found in Kamchatka diamonds.
Received 14 May 2019; accepted 26 July 2019; published 3 November 2019.
Citation: Simakin A. G. (2019), Poroelastic response to rapid decarbonatisation as a mechanism of the diamonds formation in the mantle wedge of Kamchatka, Russ. J. Earth Sci., 19, ES5006, doi:10.2205/2019ES000677.
Copyright 2019 by the Geophysical Center RAS.