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Slate in turn is converted to phyllite, which is fine-grained and found in areas of low grade metamorphism. Schist is medium to coarse-grained and found in areas of medium grade metamorphism. High-grade metamorphism transforms the rock to gneiss, which is coarse to very coarse-grained. [37]
The albite-epidote-hornfels facies is a facies at low pressure and relatively low temperatures. It is named for the two minerals albite and epidote, though they are also stable in other facies. Hornfels is a rock formed by contact metamorphism, a process that characteristically involves high temperatures but low pressures/depths. This facies is ...
Chlorite is a common mineral, found in metamorphic, igneous, and sedimentary rocks. It is an important rock-forming mineral in low- to medium-grade metamorphic rock formed by metamorphism of mafic or pelitic rock. [9]
The greenstone belts are surrounded by high-grade gneiss terrains showing highly deformed low-pressure, high-temperature (over 500 °C (932 °F)) metamorphism to the amphibolite or granulite facies. These form most of the exposed rock in Archean cratons. [38]
This low grade metamorphic technique can also be put into use when there is an absence in change of mineral structure which applies to higher grade metamorphism. [2] Early use of illite crystallinity was in the petroleum industry to determine the transition from a dry gas phase to an unproductive rock.
Slate – Metamorphic rock - A low grade metamorphic rock formed from shale or silt; Suevite – Rock consisting partly of melted material formed during an impact event – A rock formed by partial melting during a meteorite impact; Talc carbonate – A metamorphosed ultramafic rock with talc as an essential constituent; similar to a serpentinite
Zeolite facies describes the mineral assemblage resulting from the pressure and temperature conditions of low-grade metamorphism.. The zeolite facies is generally considered to be transitional between diagenetic processes which turn sediments into sedimentary rocks, and prehnite-pumpellyite facies, which is a hallmark of subseafloor alteration of the oceanic crust around mid-ocean ridge ...
In contact metamorphism (metamorphism caused by high temperatures at low pressure in the vicinity of an igneous intrusion) a local contact aureole of zones is formed around a heat source. In rocks in subduction zones , that are transported to great depths in relatively low temperatures, rare types of metamorphic zones can develop.