Abstract

Ferrobasaltic layered intrusions have been extensively studied and have contributed to our understanding of how cumulate rocks form and how layering develops. Nevertheless, some very important questions, especially concerning the composition of the liquid having crystallized these intrusions, still remain unsolved. In this talk, I will present the various hypotheses that have been proposed concerning the evolution of silicate liquid composition during the differentiation of ferrobasaltic intrusions. I will then discuss how the physical properties of the liquids affect the crystallization of the magma chambers and control the mineralogical assemblages of cumulate rocks. Finally, I will use the Sept Iles layered intrusion (Canada) has an example of ferrobasaltic layered intrusion and discuss the crystallization and geochemistry of various rocks observed within this intrusion.

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