Search results
Results From The WOW.Com Content Network
Metamorphic rocks arise from the transformation of existing rock to 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) and, often, elevated pressure of 100 megapascals (1,000 bar ) or more, causing profound physical or chemical changes.
It is important because the processes that form and exhume ultra-high-pressure (UHP) metamorphic rocks may strongly affect plate tectonics, the composition and evolution of Earth's crust. The discovery of UHP metamorphic rocks in 1984 [1] [2] revolutionized our understanding of plate tectonics. Prior to 1984 there was little suspicion that ...
The intersection represents the likely P-T condition experienced by rock in its metamorphic history. Geothermobarometry is a quantitative measurement of the P-T conditions, which is widely used in analyzing the P-T conditions of metamorphic and intrusive igneous rocks .
Impactite is rock created or modified by one or more impacts of a meteorite. [1] [2] Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact. [3] On Earth, impactites consist primarily of modified terrestrial material, sometimes with pieces of the original meteorite. [3]
Tectonites are metamorphic or tectonically deformed rocks whose fabric reflects the history of their deformation, or rocks with fabric that clearly displays coordinated geometric features that indicate continuous solid (ductile) flow during formation.
Greenstones, aside from containing basalts, also give rise to several types of metamorphic rocks which are used synonymously with 'metabasalt' et cetera; greenschist, whiteschist and blueschist are all terms spawned from the study of greenstone belts. The West African early Proterozoic greenstone belts are similar to the Archean greenstone belts.
Metamorphism of crustal rocks in which peak temperature exceeds 900 °C, recognized either by robust thermobarometry or by the presence of a diagnostic mineral assemblage in an appropriate bulk composition and oxidation state, such as assemblages with orthopyroxene + sillimanite + quartz, sapphirine + quartz or spinel + quartz, generally at pressure conditions of sillimanite stability in ...
The Catalina Schist is a metamorphic rock complex primarily exposed on Santa Catalina Island of the Channel Islands of California. It formed during the Cretaceous Period of the Mesozoic Era . Geology