Section 3 Metamorphic Rocks Metamorphic rocks form when

Section 3: Metamorphic Rocks Metamorphic rocks form when preexisting rocks are exposed to increases in temperature and pressure and to hydrothermal solutions. K What I Know W What I Want to Find Out L What I Learned

Essential Questions • What are the different types and causes of metamorphism? • How are metamorphic textures described? • How do mineral and compositional changes occur during metamorphism? • How are rocks classified using the rock cycle? Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Vocabulary Review New • • intrusive Copyright © Mc. Graw-Hill Education foliated nonfoliated regional metamorphism contact metamorphism hydrothermal metamorphism rock cycle Metamorphic Rocks

Recognizing Metamorphic Rock • When high temperature and pressure combine and change the texture, mineral composition, or chemical composition of a rock without melting it, a metamorphic rock forms. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Recognizing Metamorphic Rock • The high temperatures required for metamorphism are ultimately derived from Earth’s heat, either through deep burial or from nearby igneous intrusions. • The high pressures required for metamorphism come from deep burial or from compression during mountain building. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Recognizing Metamorphic Rock Metamorphic minerals • During metamorphism, the minerals in a rock undergo solid-state alterations, which means that they change into new minerals that are stable under the new temperature and pressure conditions. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Recognizing Metamorphic Rock Metamorphic textures • Foliated metamorphic rocks are characterized by layers and bands of minerals caused by high pressure during metamorphism. • Foliation develops when pressure is applied from opposite directions. The foliation develops perpendicular to the pressure direction. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Recognizing Metamorphic Rock Metamorphic textures • Nonfoliated metamorphic rocks are composed mainly of minerals that form with blocky crystal shapes. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Recognizing Metamorphic Rock Metamorphic textures • Increasing grain size parallels changes in composition and development of foliation. Grain size is not a factor in nonfoliated rocks. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Grades of Metamorphism • Different combinations of temperature and pressure result in different grades of metamorphism. • Each of the grades—low, intermediate, and high—is associated with a different suite of minerals and textures. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Grades of Metamorphism • Metamorphism of shale results in the formation of minerals that provide the wide variety of color observed in slate. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Types of Metamorphism Regional metamorphism • When high temperature and pressure affect large regions of Earth’s crust, they produce large belts of regional metamorphism, ranging from low grade to high grade. • Regional metamorphism results in changes in minerals and rock types, plus folding and deforming of the rock layers that make up the area. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Types of Metamorphism Contact metamorphism • When molten material, such as that in an igneous intrusion, comes in contact with solid rock, a local effect called contact metamorphism occurs. • High temperatures and moderate-to-low pressure form mineral assemblages that are characteristic of contact metamorphism. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Types of Metamorphism Hydrothermal metamorphism • When very hot water reacts with rock and alters its chemical and mineral composition, hydrothermal metamorphism occurs. • Chemical changes are common during contact metamorphism near igneous intrusions and active volcanoes. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Economic Importance of Metamorphic Rocks and Minerals • Many of the economic mineral resources that make the modern way of life possible are produced by metamorphic processes. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Economic Importance of Metamorphic Rocks and Minerals Metallic mineral resources • Although deposits of pure metals are occasionally discovered, many metallic deposits are precipitated from hydrothermal solutions. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Economic Importance of Metamorphic Rocks and Minerals Nonmetallic mineral resources • Many nonmetallic resources are also produced by metamorphism, including talc, asbestos, and graphite. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

The Rock Cycle • • The three types of rock are grouped according to how they form. Igneous rocks crystallize from magma; sedimentary rocks form from cemented or precipitated sediments; and metamorphic rocks form from changes in temperature and pressure. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

The Rock Cycle • Any rock can be changed into any other type of rock. This continuous changing and remaking of rocks is called the rock cycle. • The rock cycle shows some of the series of changes rocks undergo above and beneath Earth’s surface. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Types of Rocks Brain. POP FPO Add link to Animation from Connect. ED here. Copyright © Mc. Graw-Hill Education Metamorphic Rocks

Review Essential Questions • What are the different types and causes of metamorphism? • How are metamorphic textures described? • How do mineral and compositional changes occur during metamorphism? • How are rocks classified using the rock cycle? Vocabulary • foliated • nonfoliated • regional metamorphism Copyright © Mc. Graw-Hill Education • contact metamorphism • hydrothermal metamorphism • rock cycle Metamorphic Rocks