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A protolith (from Ancient Greek πρωτο (prōto) 'first', and λίθος (líthos) 'stone') is the original, unmetamorphosed rock from which a given metamorphic rock is formed.[1][2]
For example, the protolith of a slate is a shale or mudstone. Metamorphic rocks can be derived from any other kind of non-metamorphic rock and thus there is a wide variety of protoliths. Identifying a protolith is a major aim of metamorphic geology.
Protoliths are non-metamorphic rocks and have no protoliths themselves. The non-metamorphic rocks fall into two classes: sedimentary rocks, formed from sediment, and igneous rocks, formed from magma. The source of the sediment of a sedimentary rock is termed its provenance.
Magmatic protoliths can be further divided into three categories: ultramafic rock, mafic rock, and quartzo-feldspathic rock. Similarly, sedimentary protoliths can be classified as quartzo-feldspathic, pelitic, carbonate rocks, or some mixture of the three.[3]
On a geological time scale, the first protoliths were first formed shortly after the formation of the Earth during the Hadean eon.
^Hoinkes, G.; Hauzenberger, C. A.; Schmid, R. (2014-01-01), "Classification, Nomenclature, and Formation☆", Reference Module in Earth Systems and Environmental Sciences, Elsevier, doi:10.1016/b978-0-12-409548-9.09049-7, ISBN 978-0-12-409548-9, retrieved 2022-10-17
A protolith (from Ancient Greek πρωτο (prōto) 'first', and λίθος (líthos) 'stone') is the original, unmetamorphosed rock from which a given metamorphic...
new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F)...
type of the original rock (the protolith) is discernible, the schist is usually given a name reflecting its protolith, such as schistose metasandstone...
metamorphism creates minerals entirely based upon the chemistry of the protolith, certain 'dirty marls' and volcanic sediments may also metamorphose to...
Skarns may form by metamorphic recrystallization of impure carbonate protoliths, bimetasomatic reaction of different lithologies, and infiltration metasomatism...
Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place...
minerals present in each facies depends on the composition of the protolith. For a mafic protolith, the albite-epidote hornfels facies is characterized by albite...
Primary sedimentary textures and structures of the original carbonate rock (protolith) have typically been modified or destroyed. Pure white marble is the result...
meaning "leaf". The protolith (or parent rock) for phyllite is shale or pelite; or slate, which in turn came from a shale protolith. Its constituent platy...
metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock Metapsammite – A metamorphic rock with a protolith of quartz-rich (sandstone)...
layers. A common cause of nonhydrodynamic stress is the subjection of the protolith (the original rock material that undergoes metamorphism) to extreme shearing...
metamorphic. In the context of metamorphic rocks, the parent rock (or protolith) is the original rock before metamorphism occurred. Bedrock Regolith v...
high pressure during regional metamorphism of a protolith which is rich in aluminium (a pelitic protolith). Kyanite is also occasionally found in granite...
Napier Orogeny in Antarctica, 4,000 ± 200 Ma. 4031 Hadean Formation of protolith of the oldest known rock (Acasta Gneiss) c. 4,031 to 3,580 Ma. Possible...
original composition of and the pressure and temperature experienced by the protolith (parent rock), chemical reactions between minerals in the solid state...
temperature, or both). The original rock, prior to change (called the protolith), may be of any sort. Experimental petrology employs high-pressure, high-temperature...
Craton including gneisses and other metamorphic rocks with volcanic rock protoliths and rapakivi granites. These rocks are much older than the rest (Paleoproterozoic...
chlorite, from Maurienne Valley in the French Alps Composition Quartz Physical Characteristics Fabric Non-foliated Relationships Protoliths Quartz Sandstone...
unconsolidated sediment (protolith for future metamorphic rocks). As temperature and pressure increase with depth, a protolith passes through a diagenetic...
based on protolith, mineral composition, texture, or metamorphic facies. Naming based on texture and a pelite (e.g., shale, mudrock) protolith can be used...
and found to be felsic but is metamorphic and has no definite volcanic protolith, it may be sufficient to simply call it a 'felsic schist'. There are examples...
describe a metamorphosed sedimentary rock with a dominantly sandstone protolith. In Europe, this term was formerly used for a fine-grained, fissile, clayey...
ultramafic rock (the protolith) is peridotite, which is rich in olivine, considerable magnetite and hydrogen are produced. When the protolith is pyroxenite,...
metamorphic rock which exhibits fine laminations of clay materials. Its protolith is argillite. Kontogianni, V.; Tzortzis, A.; Stiros, S. (October 2004)...
undergone multiple deformations and multiple metamorphic episodes. The protolith age of the Narryer Gneiss Terrane is variable, but generally considered...
conditions that produce slate or phyllite, but with the parent rock (protolith) being conglomerate, rather than clay. The metaconglomerates of the Jack...
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