EXPERIMENTAL STUDY OF BINARY SOLID SOLUTIONS IN THE SYSTEM CaMgSi2O6-CaFeSi2O6-NaFeSi2O6 AND Mg AND Fe PARTITION BETWEEN Ca(Mg,Fe)Si2O6 AND K(Mg,Fe)3(AlSi3O10)[OH]2
A.R. Kotel’nikov1, A.M. Koval’skii1, N.I. Suk1, Z.A. Kotel’nikova2, P.A. Petukhov1, T.N. Koval’skaya1
1Institute of Experimental Mineralogy, Russian Academy of Sciences, Chernogolovka, 132432, Moscow Region, Russia
2Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, Staromonetnyi per. 35, Moscow, 119017, Russia
Keywords: Clinopyroxene, diopside, hedenbergite, biotite, experimental study, cation exchange equilibria
Abstract
Clinopyroxene binary solid solutions in the systems diopside-hedenbergite, diopside-aegirine, and hedenbergite-aegirine have been synthesized. Based on data from X-ray diffraction studies, the unit-cell parameters of these solid solutions have been refined, and their concentration dependences have been established. These clinopyroxene series are near-ideal continuous solid solutions. The partition of Mg and Fe between the diopside-hedenbergite binary solid solutions and biotite of the phlogopite-annite series was studied by the method of cation exchange equilibria at 650 and 750 ºC and 2 kbar. The application of KF solution as a reaction medium permitted achieving equilibrium in a considerably shorter time and from its both sides. The partition of Mg and Fe is near-ideal within the experimental error. The experimental results were compared with results of calculations based on literature data on the thermodynamic properties of pure end-members.
|
