Role of oxygen pressure in the crystallization and differentiation of basaltic magma

Author:
  • EOElburt Franklin Osborn
    Elburt Franklin Osborn
Publisher website
Google Scholar
Abstract
Two types of crystallization paths in iron oxide systems are illustrated by describing equilibrium crystallization in the fayalite field of the system FeO-Fe 2 O 3 -SiO 2 . In one type where total composition of the mixture remains constant, composition of the liquid changes along a path leading to a boundary curve and thence to an invariant point. In the other type oxygen partial pressure remains constant causing the liquid of the crystallizing mixture to follow an oxygen isobaric line on the liquidus surface. In this second type of crystallization the oxygen content of the mixture changes. These principles are extended into an examination of crystallization phenomena in the quaternary system MgO-FeO-Fe 2 O 3 -SiO 2 .