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  2. Metamorphic rock - Wikipedia

    en.wikipedia.org/wiki/Metamorphic_rock

    A metamorphic facies is a set of distinctive assemblages of minerals that are found in metamorphic rock that formed under a specific combination of pressure and temperature. The particular assemblage is somewhat dependent on the composition of that protolith, so that (for example) the amphibolite facies of a marble will not be identical with ...

  3. Metamorphism - Wikipedia

    en.wikipedia.org/wiki/Metamorphism

    Metamorphic rock formed in these settings tends to shown well-developed foliation. [33] Foliation develops when a rock is being shortened along one axis during metamorphism. This causes crystals of platy minerals, such as mica and chlorite , to become rotated such that their short axes are parallel to the direction of shortening.

  4. List of rock types - Wikipedia

    en.wikipedia.org/wiki/List_of_rock_types

    Cataclasite – Rock found at geological faults – A rock formed by faulting; Eclogite – Metamorphic rock formed under high pressure; Gneiss – Common high-grade metamorphic rock; Granulite – Class of high-grade medium to coarse grained metamorphic rocks; Greenschist – Metamorphic rock – A mafic metamorphic rock dominated by green ...

  5. Rock (geology) - Wikipedia

    en.wikipedia.org/wiki/Rock_(geology)

    Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of existing rocks. Metamorphic rocks are formed when existing rocks are subjected to such high pressures and temperatures that they are transformed without significant melting.

  6. Formation of rocks - Wikipedia

    en.wikipedia.org/wiki/Formation_of_rocks

    Igneous rocks can be seen at mid-ocean ridges, areas of island arc volcanism or in intra-plate hotspots. Metamorphic rocks once existed as igneous or sedimentary rocks, but have been subjected to varying degrees of pressure and heat within the Earth's crust. The processes involved will change the composition and fabric of the rock and their ...

  7. Subduction zone metamorphism - Wikipedia

    en.wikipedia.org/wiki/Subduction_zone_metamorphism

    Subduction zones host a unique variety of rock types formed by the high-pressure, low-temperature conditions a subducting slab encounters during its descent. [4] The metamorphic conditions the slab passes through in this process generates and alters water bearing (hydrous) mineral phases, releasing water into the mantle.

  8. Foliation (geology) - Wikipedia

    en.wikipedia.org/wiki/Foliation_(geology)

    Nonfoliated metamorphic rocks are typically formed in the absence of significant differential pressure or shear. [1] Foliation is common in rocks affected by the regional metamorphic compression typical of areas of mountain belt formation (orogenic belts). More technically, foliation is any penetrative planar fabric present

  9. Shield (geology) - Wikipedia

    en.wikipedia.org/wiki/Shield_(Geology)

    A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. [1] These rocks are older than 570 million years and sometimes date back to around 2 to 3.5 billion years.