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Vol. 29 (2026 year), No. 2, DOI: 10.21443/1560-9278-2026-29-2

Butvina V. G., Limanov E. V.
Experimental study of the interaction of model garnet-harzburgite with H₂O – CO₂ – (K, Na)Cl fluids at 5 GPa and 1 100 °С

In modern petrological and geochemical literature, considerable attention is paid to the issue of the transformation of mantle rocks during their interaction with fluids and melts of various origins. An additional approach to building a picture of the mantle metasomatism process is to conduct modeling, both experimentally in high-pressure facilities and numerically, using specialized software packages for modeling phase equilibria in systems with a given gross composition, one of which is Perple_X. In order to simulate the reactions of phlogopitization and amphibolization during mantle metasomatism, an experimental study of the interaction of a model garnet-harzburgite with a water-carbon dioxide fluid H₂O – CO₂ – (K, Na)Cl at a pressure of 5 GPa and a temperature of 1 100 °C has been conducted. It has been found that the introduction of alkaline fluid components into the system provokes modal metasomatism: clinopyroxene and spinel are formed due to the decomposition of primary orthopyroxene and garnet, phlogopite appears in potassium systems, and amphibole appears in sodium systems. At the same time, the content of Al₂O₃ in the clinopyroxene increases, and a consistent change in the parameters Ca/(Ca+Mg+Fe) and Cr/(Cr+Al) in the garnet has been observed. The obtained results are compared with thermodynamic modeling (Perple_X), which reproduces the observed phase associations and clarifies the influence of H₂O and K₂O activities on the stability of minerals.

(in Russian, стр.9, fig. 3, tables. 9, ref 11, AdobePDF, AdobePDF 0 Kb)