Lithosphere control of continental rift magmatism

Abstract

The proposition that intra-continental magmatism is caused by plumes which have fixed sources below the lithosphere is critically examined and found to be false. Repetition of alkaline/carbonatite activity at continental rift intersections, over periods of large-scale plate movement, demands that the structural fabric of the lithosphere is determining the site of the magmatism. It is concluded that the structure and thickness of the continental slab modulate the escape of heat and volatiles from the deep mantle, and the lithosphere thus also controls the character of the magmatism.