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Melting reactions in the system KAlSi_3O_8-SiO_2-H_2O to 18.5 kilobars

Lambert, I. B. and Robertson, J. K. and Wyllie, P. J. (1969) Melting reactions in the system KAlSi_3O_8-SiO_2-H_2O to 18.5 kilobars. American Journal of Science, 267 (5). pp. 609-626. ISSN 0002-9599. doi:10.2475/ajs.267.5.609.

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Synthetic sanidine with composition Or_(95)Ab_5 was crystallized from gel, and a portion was mixed with 15 wt percent natural quartz. The sanidine and sanidine-quartz mixture were reacted with 30 to 40 wt percent water in sealed platinum capsules, using piston-cylinder apparatus. The melting relationships for these two crystalline mixtures, in the presence of excess water, were determined to 18.5 kb pressure. The divariant melting intervals located for each sample, along with the results of previous studies in the system KAlSi_3O_8-SiO_2-H2_O, provided good estimates of the positions of univariant curves for the two reactions: (a) Or + V <--> L, and (b) Or + Qz + V <--> L. Values for reaction (a) are 5 kb-875°C; 10 kb-825°C; 15 kb-795°C; 20-775°C. Values for reaction (b) are 5 kb-740°C; 10 kb-710°C; 15 kb-700°C; 20 kb- 697°C. Muscovite was present in trace amounts in all runs, including those quenched from conditions well above its maximum temperature stability limit, but it was not found enclosed in glass. We therefore conclude that muscovite was a deposit from the vapor phase. Schematic phase diagrams for the system K_2O-Al_2O_3-SiO_2-H_2O indicate that muscovite would not be expected as a stable liquidus phase for mixtures on the join KAlSi_3O_8-SiO_2-H_2O at pressures less than 10 kb.

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Alternate Title:Melting reactions in the system KAlSi3O8-SiO2-H2O to 18.5 kilobars
Additional Information:© 1969 American Journal of Science. We gratefully acknowledge the following support: National Science Foundation for Grant GA-923; Advanced Research Project Agency for the assistantship for J. K. Robertson and for some of the apparatus used. We thank R. C. Newton for critical review of the manuscript.
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Advanced Research Projects Agency (ARPA)UNSPECIFIED
Issue or Number:5
Record Number:CaltechAUTHORS:20160121-140123957
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Official Citation:I. B. Lambert, J. K. Robertson, and P. J. Wyllie Melting reactions in the system KAlSi 3 O 8 -SiO 2 -H 2 O to 18.5 kilobars Am J Sci May 1, 1969 267:609-626; doi:10.2475/ajs.267.5.609
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63854
Deposited By: Tony Diaz
Deposited On:21 Jan 2016 22:23
Last Modified:10 Nov 2021 23:22

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