The Problem of the Potash-rich Basaltic Rocks

Germaine A. Joplin
Department of Geophysics, Australian National University

Summary: It is suggested that the name shoshonite be revived for a group of potash-rich basalts and that the magma from which monzonites, potash-rich syenites, many lamprophyres, nepheline monzonites, shonkinites, eovites, ijolites, leucite basalts, leucitophyres, etc., have crystallized be called the shoshonite magma-type. This series shows parallels with the alkali basalt magma series, and the question of the relation of the two magma-types is discussed.

The name latite is discussed and rejected as a name for this potash-rich magma type. It is further shown that rocks of this composition invade geosynelinal regions that have been recently stabilized, one group of shoshonites being associated with an environment that is still subjected to minor folding and showing some relation to the cale-alkaline rocks, the other a true alkaline suite associated with non-orogenic conditions.

Mineralogical Magazine; 1965 v. 34; no. 268; p. 266-275; DOI: 10.1180/minmag.1965.034.268.22
© 1965, The Mineralogical Society
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