Regional metamorphism has altered the rocks to upper greenschist
These units have widespread exposure, high thickness and metamorphosed to greenschist
facies (Aliyari et al., 2009; Alizadeh-Dinabad et al., 2013; Almasi et al., 2015; Almasi et al., 2017) (Fig.
The oldest basement forming lithologies are mafic to tonalitic rocks metamorphosed under epidote amphibolite- and greenschist
The oldest formations in this area are Proterozoic greenschist
facies metamorphic rocks of the Heilongjiang Group.
Shi, "Study on creep damage constitutive relation of greenschist
specimen," Chinese Journal of Rock Mechanics and Engineering, vol.
Regional metamorphism is mostly at a greenschist
grade, but ranges locally from subgreenschist to amphibolite facies [46, 47].
The low magnetic values are related to the metamorphism of this unit into greenschist
1b-c), the walls of which display folded beds of sandstone, shale and coal that were deformed and metamorphosed to lower greenschist
facies in the Late Stephanian or Permian (ca.
The existing Burgers model has been modified based on the brittle damage characteristics of the greenschist
structure surface and the curves of shear creep tests.
The earliest (D1) was the most intense, and was synchronous with peak greenschist