What do you mean by metamorphic facies?
What do you mean by metamorphic facies?
A metamorphic facies is a group of rocks which for identical bulk composition exhibits an identical mineral composition, but whose mineral composition for varying bulk composition varies according to definite laws.
What is metamorphism and plate tectonics?
Metamorphic rocks result from the forces active during plate tectonic processes. Generally speaking, the greater the tectonic forces, the higher the pressures and temperatures affecting a rock mass and the greater the amount of resulting structural deformation and metamorphism. …
What is a metamorphic setting?
Section 1 Metamorphic Rock Type and Tectonic Setting Metamorphism is a process of mineral assemblage and texture variation that results from the physical-chemical changes of solid rocks, caused by factors such as crust movement, magma activity, or thermal fluid change in the earth.
What are the types and tectonic settings of metamorphism?
1 Environments of metamorphism in the context of plate tectonics: (a) regional metamorphism related to mountain building at a continent-continent convergent boundary, (b) regional metamorphism of oceanic crust in the area on either side of a spreading ridge, (c) regional metamorphism of oceanic crustal rocks within a …
What is a facies in geology?
In geology, a facies (/ˈfeɪʃiːz/ FAY-sheez; plural also facies) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formation), and the changes that may occur in those attributes over a geographic area.
What is amphibolite facies in geology?
amphibolite facies, one of the major divisions of the mineral-facies classification of metamorphic rocks, the rocks of which formed under conditions of moderate to high temperatures (500° C, or about 950° F, maximum) and pressures. Water is usually lost from the parent rock as these changes take place.
What tectonic setting makes regional metamorphism?
Regional metamorphism occurs when rocks are buried deep in the crust. This is commonly associated with convergent plate boundaries and the formation of mountain ranges. Because burial to 10 km to 20 km is required, the areas affected tend to be large.
In what plate tectonic setting does regional metamorphism usually take place?
Convergent plate boundaries
Regional metamorphism. In what plate tectonic setting does regional metamorphism usually take place? Convergent plate boundaries.
What do you mean by metamorphism in geography?
Metamorphism is the addition of heat and/or pressure to existing rocks, which causes them to change physically and/or chemically so that they become a new rock. Any type of rock—igneous, sedimentary, or metamorphic—can become a metamorphic rock.
What environment produces the Blueschist facies?
Blueschist, which contains the blue mineral glaucophane, forms in subduction zones under high pressures and low temperatures, and its rare occurrence in Precambrian rocks may indicate that temperatures in early subduction zones were too high for its formation.
What do you mean by facies?
Definition of facies 1 : general appearance a plant species with a particularly distinct facies. 2 : an appearance and expression of the face characteristic of a particular condition especially when abnormal adenoid facies.
What is facies analysis?
Facies analysis is the description and classifi- cation of any body of sediment followed by the interpretation of its processes and environments of deposition, usually in the form of a facies model (Table 1).
Which is the best definition of a metamorphic facies?
A “metamorphic facies” therefore, may be defined as a group of metamorphic rocks that have formed under the same set of phsico-chemical conditions and is characterized by a definite set of minerals. P.
What are the P-T conditions of a metamorphic rock?
Metamorphic facies, defined by mineral assemblage observed from the metamorphic rocks, represent the P-T conditions at Tmax of the P-T-t path in most cases ( Fig. 3 E). Across an orogenic belt, a progressive change of metamorphic facies is observed.
How are mineral assemblages in metamorphic rocks determined?
As metamorphic rocks change under heat and pressure, their ingredients recombine into new minerals that are suited to the conditions. The concept of metamorphic facies is a systematic way to look at the mineral assemblages in rocks and determine a potential range of pressure and temperature (P/T) conditions that were present when they formed.
How are plate tectonics and metamorphism related to each other?
All of the important processes of metamorphism that we are familiar with can be directly related to geological processes caused by plate tectonics. The relationships between plate tectonics and metamorphism are summarized in Figure 7.14, and in more detail in Figures 7.15, 7.16, 7.17, and 7.19.
