Blueschist facies indicate
A) formation at high temperature and high pressure.
B) evidence of an ancient subduction zone.
C) migmatite melting in a subduction zone.
D) all of these

Question

Quizplus · Accepted Answer

Blueschist facies are typically formed in subduction zones where oceanic crust is subducted beneath continental crust. Therefore, the presence of blueschist facies is evidence of an ancient subduction zone. Although high pressure is required for the formation of blueschist facies, the temperatures are relatively low compared to other metamorphic facies such as granulite facies, making choice A incorrect. Migmatite melting is not directly related to blueschist facies, making choice C incorrect. Thus, choice B is the best answer.

Blueschist Facies Indicate