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Chemical and Physical Constraints for Crystallization of Feldspathoids and Melilite in Potassium-Rich Rocks

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

Abstract

Leucite appears as a mineral in K-rich lavas, if the SiO2 content of the rock varies between 44 and 56 wt% (Washington 1906). When the SiO2 content is close to 56 wt%, it may appear but then the SiO2/K2O ratio should be below 10; in that case the K2O content of the rock is close to 6 wt%. In silica-deficient rocks (SiO2 < 45 wt%), leucite may appear even though the K2O content is slightly higher than 1 wt%. The K2O/Na2O ratio is always greater than one in leucite-bearing rocks, but the prohibitive tendency of high soda may be eliminated if the SiO2/K2O ratio is low.

Keywords

Oxygen Fugacity SiO2 Content Ascent Rate Primary Phase Field Kimberlitic Magma 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer India 2015

Authors and Affiliations

  1. 1.Mineralogy and PetrologyUniversity of AllahabadAllahabadIndia

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