Experimental investigation of silicate systems containing two volatile components; Part 3, The effects of SO_3, P_2O_5, HCl, and Li_2O, in addition to H_2O, on the melting temperatures of albite and granite

Abstract

Mixtures composed of 50 weight percent of silicate (albite, granite, or glass) and 50 weight percent of aqueous solutions of H_2SO_4, H_3PO_4, HCl, and LiOH were sealed in gold capsules and held at various temperatures at a constant pressure of 2750 bars. In the presence of H_2O alone at this pressure, albite melts at 810°C and granite begins to melt at 665°C. In the presence of aqueous solutions containing 5 weight percent of the second volatile component the temperature of beginning of melting of albite is 710°C for SO_3, 660°C for P_2O_5, and 708°C for HCl; and that of granite is 665°C for SO_3, 645°C for P_2O_5, 680°C for HCl, and 575°C for LiO_2. Applications of these experimental results, together with results obtained previously for the volatile components HF, NH_3, and CO_2, are briefly discussed in connection with the origin of granites, pegmatites, alumina- undersaturated alkaline rocks, and thermal waters of volcanic origin.