Clicker The transformation of one rock Metamorphism and Metamorphic Rocks into another by solid state recrystallization is known as a b c d e Sedimentation Metamorphism Melting Metasomatism Hydrothermal alteration Metamorphism Metamorphism is the solid state transformation of preexisting rock into texturally or mineralogically distinct new rock as the result of high temperature high pressure or both Metamorphism Diamond is Metamorphic The mineralogy of a metamorphic rock changes with temperature and pressure In general the highest temperature mineral assemblage is preserved It is possible to infer the highest P T conditions from the mineralogy 1 Metamorphic Environments Regional metamorphism involves the burial and metamorphism of entire regions hundreds of km2 Contact metamorphism results from local heating adjacent to igneous intrusions several meters Metamorphic Environments Metamorphic Environments Where do you find metamorphic rocks In the mountains and in continental shield areas Why Because elsewhere they are covered by sediments Regional Metamorphism Because the tectonic forces required to bury metamorphose and reexhume entire regions are slow most regionally metamorphosed terranes are old 500 MY and most Precambrian 500 MY terranes are metamorphosed Regional Metamorphism Regional Metamorphism Regional metamorphism is typically Regional metamorphism is typically isochemical composition of rock does not change although water may be lost Metasomatism is a term for nonisochemical metamorphism Contact metamorphism is typically metasomatic isochemical composition of rock does not change although water may be lost Metasomatism is a term for nonisochemical metamorphism Contact metamorphism is typically metasomatic 2 Conditions of Metamorphism Changing the mineralogy of a sediment requires temperature 300 C and pressures 2000 atmospheres 6 km deep Temperature increases downward at 20 C km in crust Pressure increases downward at 1000 atm 1kbar per 3 km 330 bar km Effect of Increasing Temperature Increases the atomic vibrations Decreases the density thermal expansion Increases the speed of reactions Effect of Increasing Pressure Increases the density compression Pressure can be hydrostatic equal in all directions or Pressure can be directed as a shear which can cause Foliation alignment of platy minerals Lineation alignment of needle like minerals Temperature and Pressure Continental temperatures increases by 30 C km 90 C 3 km Pressure increases by 330 atm km 1kbar 3km 3 Metamorphosed Sediments Conglomerate Sandstone Shale Shale Shale Limestone Gypsum Schist Metamorphosed Shale Metaconglomerate Quartzite Phyllite Slate Schist Gneiss Marble Anhydrite Blueschist Marble Blueschist Metamorphosed Shale Limestone Marble Metamorphosed Igneous Rock Granite Diorite Basalt Gabbro Gneiss Gneiss Eclogite All are high grade Partial melting Migmatite 4 Garnet in Schist Gneiss Migmatite Partial Melting Migmatite Partial Melting Garnet Amphibolite Gneiss Inner Gorge Grand Canyon 5 Garnet Amphibolite Gneiss Garnet Chlorite Schist Diamond in Eclogite Blueschist Aosta Valley Italy Black Canyon of the Gunnison Metamorphism Terms Regional Metamorphism Contact Metamorphism Isochemical Metasomatism Hydrostatic Foliation Lineation Terrane Quartzite Phyllite Slate Schist Gneiss Marble Eclogite Granulite Migmatite 6 Clicker Question Which is a term for metamorphism that involves significant chemical change A Regional metamorphism B Contact metamorphism C Metasomatism D Diapirism E Lithification Clicker Question The high grade metamorphic equivalent of limestone is A Eclogite B Quartzite C Marble D Slate E Gneiss Clicker Question A shale caught in a subduction zone and carried to high pressures at low temperatures would be a A Blueschist B Quartzite C Marble D Slate E Anhydrite Clicker Question Which is a term for metamorphism that involves significant chemical change A Regional metamorphism B Contact metamorphism C Metasomatism D Diapirism E Lithification Clicker Question The high grade metamorphic equivalent of limestone is A Eclogite B Quartzite C Marble D Slate E Gneiss Clicker Question A shale caught in a subduction zone and carried to high pressures at low temperatures would be a A Blueschist B Quartzite C Marble D Slate E Anhydrite 7
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