Ternary Systems with Feldspathoids

  • Alok Krishna Gupta
Part of the Springer Geology book series (SPRINGERGEOL)


In the fractionation scheme of basaltic magmas, CaO, MgO and total iron oxide (FeO + Fe2O3) contents decrease progressively, and those of Al2O3, Na2O and K2O increase with respect to silica (Harker 1909), as a result of which the residual liquid becomes enriched with respect to NaAlSiO4 (nepheline ), KAlSiO4 (kalsilite ), and SiO2 components. Bowen (1928), therefore, referred to the system NaAlSiO4–KAISIO4–SiO2 as petrogny’s residua system, in which the NaAISi3O8 (albite)–KAlSi3O8 (K-feldspar ) join acts as a thermal barrier at low pressures.


Bulk Composition Liquid Composition Alkali Feldspar Incongruent Melting Lead Isotopic Ratio 
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© Springer India 2015

Authors and Affiliations

  1. 1.Mineralogy and PetrologyUniversity of AllahabadAllahabadIndia

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