| Abstract: | Recent research into layered intrusions (intrusive bodies in which there are layers of different mineralogical composition) provides an interesting example of 'role–reversal'. Traditionally, crystal settling has been regarded as the main agent of differentiation, with magma convection as a useful subsidiary factor. Now the behaviour of the fluid phase – before, during and after the main crystallisation period – is assuming increasing importance, even to the extent of eliminating the need for crystal settling altogether. The 'new wave' of ideas is stimulating and challenging, but by no means sounds the death–knell of conventional magmatic sedimentation. |
