PETROLOGY OF MAFIC-ULTRAMAFIC LAYERED INTRUSIONS IN PRECAMBRIAN PLATFORMS: STATE OF THE ART AND NEW APPROACHES

Abstract

Phase layering in mafic and ultramafic intrusions cannot be explained in terms of convection and crystal accumulation in magma chamber, as vigorous convection of melts enriched in suspended crystals is impossible. Emplacement of a heterogeneous magma containing 40-50% crystals is rather accompanied with compaction of the cumulate pile, whereby the intercumulus liquid seems to squeeze out towards the roof of the chamber