Living Reference Work Entry

Encyclopedia of Geochemistry

Part of the series Encyclopedia of Earth Sciences Series pp 1-6

Date: Latest Version

Fractional Crystallization and Assimilation

  • Frank SperaAffiliated withDepartment of Earth Science, University of California Santa Barbara Email author 
  • , Melissa ScruggsAffiliated withDepartment of Earth Science, University of California Santa Barbara Email author 

Definitions

Fractional crystallization is one of the most important petrogenetic processes contributing to the compositional diversity of magmas and associated igneous rocks of the Earth’s continental and oceanic crust. N.L. Bowen, one of the guiding lights of modern petrology, brought this mechanism to the fore in the early part of the twentieth century. A multicomponent silicate liquid (melt) undergoes fractional crystallization when crystals precipitated from the melt do not remain in equilibrium with residual melt during crystallization. This may occur, for example, by physical separation of crystals from melt (e.g., by gravitative settling or floatation of crystals) or by sluggish crystal-melt reaction kinetics (nucleation and growth) without physical separation. Fractional crystallization in multicomponent silicate liquids is complex compared to crystallization in unary systems because the composition of removed crystals is gene ...

This is an excerpt from the content