Week 5-6. Paired metamorphic belts

Paired metamorphic belts

The concept of paired metamorphic belts was originally theorized by the Japanese geologist, Akiho Miyashiro in 1961. The parallel arrangement between the metamorphic belts and the similar ages of each belt, this led Miyashiro to the idea that metamorphic belts formed together as pairs.

Paired metamorphic belts

  • Are sets of parallel linear rock units that display contrasting metamorphic mineral assemblages.
  • These paired belts develop along convergent plate boundaries where subduction is active.
  • Each pair consists of one belt with a low-temperature, high-pressure metamorphic mineral assemblage.
  • Another characterized by high-temperature, low-pressure metamorphic minerals.

Example of paired metamorphic belts

  • The example is represented by the western U.S. where the Franciscan complex contains rocks metamorphosed at high pressure and low temperature.
  • Whereas rocks exposed in the and Sierra Nevada  rocks metamorphosed at low pressure and high temperature.

  • Occurrences of paired belts have since been recognized throughout the world include areas in New Zealand, Indonesia, Washington State in the U.S. , Chile, the Alps of central Europe and the northern coast of South America.

 

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