POLYFACIES MODE OF IGNEOUS ROCKS AND METEORITES

Abstract

The polyfacies mode of rocks and meteorites is related to their formation in several stages, which strongly differ in PT conditions. The polyfacies mode appears in igneous rocks during crystallization of magma owing to decrease in lithostatic pressure (depth) at the following stages: primary magma chamber–intermediate magma chambers–final consolidation of magma in intrusions or volcanic effusions (low-pressure minerals and volcanic glass). In contrast, minerals transported from deep-seated chambers are represented by high-pressure abyssal modifications.