Phase equilibria in the undersaturated part of Petrogeny's residua system; a preliminary graphical analysis of its potassic field with potential implications for the origin of pseudoleucite

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Authors:Korobeinikov, A. N.; Dubrovskii, Mikhail; Laajoki, Kauko; Gehör, Seppo
Author Affiliations:Primary:
Kola Scientific Centre, Geological Institute, Apatity, Russian Federation
Other:
University of Oulu, Finland
Volume Title:Neues Jahrbuch für Mineralogie. Monatshefte
Source:Neues Jahrbuch für Mineralogie. Monatshefte, 1998(6), p.241-252. Publisher: E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Federal Republic of Germany. ISSN: 0028-3649
Publication Date:1998
Note:In English. 24 refs.; illus., incl. 1 table, table
Summary:Several P(H2O)-T projections with isobaric T-X sections for the system NaAlSiO4-KAlSiO4-SiO2-H2O have been constructed for a range of P(H2O) reasonable for igneous activity. In addition to earlier known relationships, two eutectics (nepheline + kalsilite + leucite = melt and nepheline + leucite + orthoclase = melt) are depicted at different P(H2O) values. The excess amounts of Na2O within micrographic nepheline-orthoclase-kalsilite intergrowths are responsible for forming 'pseudoleucite'. These nepheline-orthoclase-kalsilite microsymplectites can be interpreted either as products of direct eutectic crystallization of these minerals from a magma or eutectic crystallization of nepheline + orthoclase + leucite or nepheline + kalsilite + leucite, with subsequent subsolidus breakdown of leucite and formation of additional amounts of kalsilite and orthoclase within the intergrowths. [R.A.H.]
Sections:Experimental mineralogy
Subsections:Silicates
Subjects:Albite; Alkali feldspar; Crystallization; Feldspar group; Framework silicates; Genesis; Graphic texture; Intergrowths; Kalsilite; Leucite; Liquid phase; Melts; Nepheline; Nepheline group; Orthoclase; P-T conditions; Phase equilibria; Plagioclase; Pseudoleucite; Silicate melts; Silicates; Symplectite; Textures
Abstract Numbers:99M/384
Record ID:2001059524
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from Geoline, Bundesanstalt fur Geowissenschaften und Rohstoffe
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