The transformation of existing rock, the protolith, into rock with a different mineral composition or texture, usually above 150 degrees Celsius and often at elevated pressure or in the presence of chemically active fluids, while the rock stays mostly solid. Regional, contact, hydrothermal, shock and dynamic metamorphism differ in their characteristic temperatures, pressures and fluids, and the process is distinct from weathering and diagenesis, which work at or just beneath the surface. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
TimescaleThousands of years near a hot intrusion (contact metamorphism) to tens of millions of years during regional metamorphism accompanying mountain building. 1 Driving ForceElevated heat and pressure, generated by burial, tectonic stress or contact with magma, acting on existing rock without melting it. 1 Resulting FeatureRecrystallizes the minerals and often the texture of the parent rock, producing metamorphic rock such as marble from limestone or schist from shale. 1 SignificanceMetamorphic rock and its mineral assemblages record the temperature and pressure history of a rock, revealing its tectonic setting long after the original rock is gone. 1 Driving Force
Driving Force (category) Driving Force (category) Timescale
Timescale (category) Metamorphism
Filter Results1 entry
Connections
Causes
Forms by regional or contact metamorphism of mafic igneous rock (basalt or gabbro) or of impure marl.
Forms under the high-pressure, low-temperature metamorphism characteristic of subduction zones.
Forms only under the high-pressure metamorphism of deep subduction, converting basaltic protoliths to garnet and omphacite.
Source Gneiss (Wikipedia)
Forms under low-grade regional metamorphism of mafic protoliths, named for its diagnostic green chlorite and actinolite.
The textbook contact-metamorphic rock, baked fine-grained and hard by heat from a nearby igneous intrusion.
Source Marble (Wikipedia)
Forms at the highest metamorphic grades, where partial melting segregates light and dark mineral bands.
A fault rock formed by dynamic (ductile shear) metamorphism, grain size reduced along a shear zone.
Source Outer Hebrides (Wikipedia)
Caused by regional metamorphism (heat and pressure, usually tectonic compression in orogenic belts) acting on sandstone.
Source Quartzite (Wikipedia)
Typically forms during regional metamorphism accompanying mountain building.
Source Schist (Wikipedia)
Source Serpentinite (Wikipedia)
A classic contact-metamorphic rock formed where an igneous intrusion metasomatizes carbonate country rock.
Derived from a shale-type sedimentary rock through low-grade regional metamorphism.
Source Slate (Wikipedia)
Source Soapstone (Wikipedia)
In Discipline
Metamorphic petrology is the study of metamorphism.
Source Metamorphism (Wikipedia)
Sources
1. Metamorphism (Wikipedia)
Wikimedia FoundationLead sectionQuote, Lead section
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture.
Quartzite (Wikipedia)
Wikimedia FoundationCauses: Quartzite, Lead sectionQuote, Causes: Quartzite, Lead section
Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts, and hence quartzite is a metasandstone.
Marble (Wikipedia)
Causes: Marble, Lead paragraphQuote, Causes: Marble, Lead paragraph
Marble is a metamorphic rock consisting of carbonate minerals (most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2) that have recrystallized under the influence of heat and pressure
Gneiss (Wikipedia)
Causes: Gneiss, Lead paragraphQuote, Causes: Gneiss, Lead paragraph
Gneiss ( NYSE) is a common and widely distributed type of metamorphic rock
Soapstone (Wikipedia)
Wikimedia FoundationCauses: Soapstone, Lead paragraphQuote, Causes: Soapstone, Lead paragraph
Soapstone (also known as steatite or soaprock) is a talc-schist, which is a type of metamorphic rock
Serpentinite (Wikipedia)
Wikimedia FoundationCauses: Serpentinite, Lead paragraphQuote, Causes: Serpentinite, Lead paragraph
Serpentinite is a metamorphic rock composed predominantly of serpentine group minerals formed by serpentinization of mafic or ultramafic rocks
Outer Hebrides (Wikipedia)
Causes: Outer Hebrides, Lead sentenceQuote, Causes: Outer Hebrides, Lead sentence
Most of the islands have a bedrock formed from ancient metamorphic rocks, and the climate is mild and oceanic.
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