polymetamorphism

polymetamorphism

[¦päl·i‚med·ə′mȯr‚fiz·əm]
(geology)
Polyphase or multiple metamorphism whereby two or more successive metamorphic events have left their imprint upon the same rocks.
References in periodicals archive ?
From the whole story of polymetamorphism it seems that kyanite belongs to the early events with deformation and andalusite and sillimanite (fibrolite) to the late (contact) metamorphism.
Important relationships seen at both macroscopic and microscopic scales include (1) rocks of the shear zone have undergone polymetamorphism, (2) an earlier phase of actinolitic amphibole (greenschist facies) is replaced in areas by a later phase of hornblendic amphibole (amphibolite facies), (3) zones of high strain correlate with rocks with a larger amount of hornblende, and (4) zones of lower strain correlate with rocks with a larger amount of porphyroclastic actinolite, surrounded by significant amounts of hornblende.