Imperial College Rock Library

Glossary: Barrovian Zones

    Barrovian zones are metamorphic zones that describe the changes in metamorphic mineral assemblages that occur in regionally metamorphosed pelitic rocks characterised by the Highlands of Scotland. Barrovian metamorphism is associated with many orogenic belts. Buchan metamorphism is similar to Barrovian but has elevated temperatures.
 
Barrovian zones are defined by the first appearance of index minerals that generally persist into higher grade zone (higher temperature). With increasing temperature these minerals are chlorite, biotite, garnet, staurolite, kyanite, and sillimanite. The zones are named after the index mineral. Barrovian zones extend across greenschist; amphibolite and granulite metamorphic facies.
 
The boundaries between zones form lines at the surface known as isograds. Often one or more of the zones in the Barrovian series may be missing.

Related Terms

metamorphic zone, metamorphic grade, metamorphic facies, regional metamorphism, index mineral