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saved searches - My saved topics - My newsletter Syenites are
usually peralkaline and peraluminous, with high proportions of
alakali elements and aluminium. Syenites are formed from
alkaline igneous activity, generally formed in thick continental
crustal areas, or in Cordilleran subduction zones. To produce a
syenite, it is necessary to melt a granitic or igneous protolith
to a fairly low degree of partial melting. This is required
because potassium is an incompatible element and tends to enter
a melt first, whereas higher degrees of partial melting will
liberate more calcium and sodium, which produce plagioclase, and
hence a granite, adamellite or tonalite. Syenite is not a common
rock, some of the more important occurrences being in New
England, Arkansas, Montana, New