Planar arrays of synthetic fluid inclusions in spontaneously nucleated forsterite crystals grown at constant pressure and temperature in a hydrostatic environment

Abstract

Planar arrays of H 2O-CO 2-NaCl fluid inclusions have been observed in synthetically produced forsterite crystals which were nucleated and grown at constant P and T in a hydrostatic environment. Planar inclusion arrays are only observed in two runs performed with fluid compositions of 0.31 and 0.26 mol% CO 2 (moles CO 2/(total moles fluid)) and 25 and 40 wt% NaCl relative to H 2O, respectively. The origin of these inclusion arrays is probably related to the decoration of either 1. (1) irregular growth fronts formed during host growth or 2. (2) fractures resulting from stress buildup caused by lattice misfits formed during rapid host growth (as suggested by Roedder, 1984). The distinction between these two mechanisms determines whether these inclusions are of primary or pseudosecondary origin. Regardless of the mechanism, these experiments demonstrate that curved planar surfaces can be generated in a crystal growing under constant hydrostatic pressure-temperature conditions.