What is Divariant reaction?
Varying the pressure or temperature within defined limits will not initiate reactions within the equilibrium assemblage of minerals. Since two independent variables, pressure and temperature, can be changed or varied without upsetting the equilibrium, the assemblage of minerals is said to be in divariant equilibrium.
What are the major general types of metamorphic reactions?
Metamorphic reactions are divided into solid-solid, volatile-involving and melting reactions. Solid-solid reactions involve polymorphic transformation, solid net transfer, exchange and exsolution reactions.
What are metamorphic dehydration reactions?
Metamorphic reactions influence the evolution of the Earth’s crust in a range of tectonic settings. We analyse the dehydration of gypsum to form bassanite and H2O which, like most dehydration reactions, produces a solid volume reduction leading to the formation of pore space.
What is metamorphic mineral reaction?
A metamorphic reaction is a chemical reaction that takes place during the geological process of metamorphism wherein one assemblage of minerals is transformed into a second assemblage which is stable under the new temperature/pressure conditions resulting in the final stable state of the observed metamorphic rock.
What is net transfer reaction?
Net-transfer reactions involve chemical components being “transferred” from one phase or set of phases to others (new phases are produced as old ones disappear). An example is: anorthite = grossular + kyanite + quartz. Net-transfer reactions may be terminal reactions or tie-line flip reactions (discussed below).
What is Divariant?
divariant assemblage Two or more metamorphic minerals in equilibrium over a range of pressure and temperature (see METAMORPHISM). Since two independent variables, pressure and temperature, can be changed or varied without upsetting the equilibrium, the assemblage of minerals is said to be in divariant equilibrium.
What is prograde and retrograde metamorphism?
In metamorphic rock: Retrograde metamorphism. In general, the changes in mineral assemblage and mineral composition that occur during burial and heating are referred to as prograde metamorphism, whereas those that occur during uplift and cooling of a rock represent retrograde metamorphism.
What are types of metamorphism?
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.
How do solid solid net transfer reactions differ from polymorphic transformations?
Solid-solid net transfer reactions (often just called solid-solid reactions) occur among solid phases of differing composition. Polymorphic reactions are a special type of solid-solid reaction that involves phases of identical composition.
What is prograde metamorphism?
In general, the changes in mineral assemblage and mineral composition that occur during burial and heating are referred to as prograde metamorphism, whereas those that occur during uplift and cooling of a rock represent retrograde metamorphism.
What is an Univariant system?
[¦yü·nə¦ver·ē·ənt ′sis·təm] (thermodynamics) A system which has only one degree of freedom according to the phase rule.
What is a solid-solid net transfer reaction?
Solid-solid net transfer reactions(often just called solid-solid reactions) occur among solid phases of differing composition. These phases may include elements found in fluids (H, C), but those elements are conserved in the solid phases so that no fluid phases (H2O, CO2) are involved as reactants or products.
What is a net transfer reaction?
Net-transfer reactions involve chemical components being “transferred” from one phase or set of phases to others (new phases are produced as old ones disappear). An example is: Net-transfer reactions may be terminal reactions or tie-line flip reactions (discussed below).
Why are some solid-solid reactions continuous?
Many solid-solid reactions are continuousbecause they involve phases whose compositions are changing as their modes change. This occurs because the phases contain appreciable solid solution. Specific reactions are difficult to express, but schematically, one would be:
What is a fluid solid reaction?
Fluid–solid reactions usually involve the adsorption of fluid reactants at preferred sites on the solid surface and the formation of nuclei of the solid product. For small particles the period of the formation and growth of the nuclei occupies essentially the entire conversion range.