Staurolite stability depending on the H<sub>2</sub>O:CO<sub>2</sub> ratio in the fluid: thermodynamic analysis of mineral parageneses
The article discusses the solution to the problem of the staurolite stability inconsistency obtained experimentally and empirically, known as the «staurolite dilemma». The authors consider the influence of the water- carbon dioxide fluid composition on the position of staurolite parageneses in the PT space using thermodynamic modeling. It was found that with a decrease of H<sub>2</sub>O fraction in the fluid, the position of staurolite-forming reactions moves to lower PT; quantitative estimates of these displacements were obtained. It is concluded that it is necessary to take into account the composition of the fluid (water activity) to make experimental results close to natural data.