Processes which modify the composition of primary magmas

Abstract

In Chapter 3 we discussed the origins of the spectrum of primary basic and ultrabasic magmas generated by partial melting processes within the upper mantle. Once such magmas have segregated from their source region they may undergo a variety of complex fractionation, mixing and contamination processes en route to the surface, during transport and subsequent storage in high-level magma chambers. These processes are of fundamental importance in producing the diversity of igneous rocks presently exposed at the Earth’s surface.