What is Barrovian metamorphism?
Barrovian metamorphism takes place during regional metamorphism, caused by crustal thickening in the roots of an orogenic belt (under mountain chains). Barrovian zones are especially easy to recognize in pelitic rocks.
What are the different types of metamorphic zones?
The sequence of zones now recognized, and the typical metamorphic mineral assemblage in each, are:
- Chlorite zone. Pelitic rocks are slates or phyllites and typically contain chlorite, muscovite, quartz and albite.
- Biotite zone.
- Garnet zone.
- Staurolite zone.
- Kyanite zone.
- Sillimanite zone.
Which type of metamorphism Favours growth of dense minerals?
In general, increasing pressure favours denser mineral structures, whereas increasing temperature favours anhydrous and less dense mineral phases.
Which of the following lists the rocks in the order of increasing grain size and increasing grade of metamorphism?
In order of increasing grain size, foliated textures are referred to as SLATY (aphanitic, very fine-grained), PHYLLITIC (aphanitic, fine-grained), SCHISTOSE (phaneritic). The corresponding rock types are called SLATE, PHYLLITE, and SCHIST. These rocks are not normally banded.
How many zones are there in barrovian zone?
In Barrovian metamorphism there are three facies. Commonly we call then low, middle, and high grade metamorphism, but geologically they are the greenschist facies, amphibolite facies, and granulite facies.
What type of tectonic setting does barrovian style metamorphism generally occur?
metamorphism, the Barrovian sequence, occurs in subduction zone backarcs prior to and not, as commonly inferred, as a consequence of heating during continental collision orogeny.
Which rock can form in a contact metamorphic zone?
The original rock with thermal contact metamorphism is mainly mudstone, carbonate rock, clastic rock, and igneous rock that can form different thermal contact metamorphic rock types.
Which metamorphism is associated with subduction zone?
Subduction zone metamorphism is characterized by a low temperature, high-ultrahigh pressure metamorphic path through the zeolite, prehnite-pumpellyite, blueschist, and eclogite facies stability zones of subducted oceanic crust.
Which rock is only formed by regional metamorphism?
Regional metamorphism usually produces foliated rocks such as gneiss and schist.
What are the five basic textures of metamorphic rocks?
The five basic metamorphic textures with typical rock types are:
- Slaty: slate and phyllite; the foliation is called ‘slaty cleavage’
- Schistose: schist; the foliation is called ‘schistocity’
- Gneissose: gneiss; the foliation is called ‘gneisocity’
- Granoblastic: granulite, some marbles and quartzite.
Which rocks comprise the barrovian sequence?
Barrow outlined a progression of index minerals, named the Barrovian Sequence, that represents increasing metamorphic grade: chlorite (slates and phyllites) -> biotite (phyllites and schists) -> garnet (schists) -> staurolite (schists) -> kyanite (schists) -> sillimanite (schists and gneisses).
What minerals are in Blueschist?
Abstract. The blueschist metamorphic facies are characterized by the minerals jadeite, glaucophane, epidote, lawsonite, and garnet. They record metamorphism in the cool high-pressure/low-temperature thermal gradients at less than 7°C/km in subduction zones in the last 1 billion years.
What type of metamorphism is quartzite?
Contact (heat-dominated) metamorphism occurs when molten rock (magma) comes into contact with other surrounding rocks (called the country rock)….
Summary Chart of Common Metamorphic Rocks | Original Rocks | sandstone |
---|---|---|
Metamorphic Equivalent | quartzite | |
Foliated? | no | |
Metamorphism | regional & contact |
What types of rocks are formed at subduction zones?
Subduction zone has distinct metamorphic rocks: formation of jadeite and glaucophane of blueschist faceis. Metamorphism in subduction zone is related to dewatering processes in magma generation. Dewatering and higher pressure and temperature induce prograde metamorphism.
Which of the following minerals is typically found in the metamorphic rocks found along the subduction zone?
Hydrous minerals of a subducting slab The most significant hydrous minerals are lawsonite (11 wt% H2O), phlogopite (2 wt% H2O) and amphibole (2 wt% H2O).
What are 3 metamorphic textures?
Metamorphic rock textures are foliated, non-foliated, or lineated are described below.
What are the 3 types of metamorphism?
There are three ways that metamorphic rocks can form. The three types of metamorphism are Contact, Regional, and Dynamic metamorphism. Contact Metamorphism occurs when magma comes in contact with an already existing body of rock.
What minerals are in eclogite?
Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with small amounts of various other stable minerals—e.g., rutile. They are formed when volcanic or metamorphic rocks rich in such mafic minerals are subjected to extremely high pressures and moderate to relatively high temperatures.