Why is the regional metamorphism of ocean crust in a subduction zone considered separately from regular regional metamorphism?
A) Because this setting does not involve any strain deformation.
B) The ocean crust has no hydrous minerals to destroy or recrystallize.
C) Unlike regular regional metamorphism, this does not occur on plate margins.
D) Both the basaltic composition and very low geothermal gradient (Low T, Hi P) are unique and lead to different facies than seen in continental rocks.

Question

Quizplus · Accepted Answer

The ocean crust undergoing subduction experiences unique conditions due to its basaltic composition and the very low geothermal gradient (Low Temperature, High Pressure) it encounters. This combination leads to the formation of metamorphic facies that are distinct from those found in continental settings, thus necessitating a separate consideration from regular regional metamorphism.

Why Is the Regional Metamorphism of Ocean Crust in a Subduction