Sedimentary Rocks: Review

Metamorphic Rocks Dr. David Steer

Rock Cycle

Metamorphic Rocks Change in composition and/or texture of a rock Occurs as the result of increasing pressure and/or temperature.

Regional Metamorphism Regional metamorphism occurs when rocks undergo increased temperatures and pressures Associated with the formation of mountain belts. Rocks may be buried to great depths (10-20 km) Temperatures in excess of 700 oC and pressures of 7 kilobars (7 million atmospheres). Increase in grain size Platy minerals become aligned (foliated) At high enough grades segregation of light and dark minerals occur (gneiss)

Regional Metamorphism Draw a schematic picture of the process

Examples of Regional Metamorphic Rocks Schist Forms when mudrocks are heated Gneiss Forms when rocks ranging from mudrocks to granites are heated and pressurized

Contact Metamorphism Contact metamorphism occurs when rocks come in contact with a heat source (usually a magma body). Essentially the rocks are getting baked, like in an oven. Grain size increases as the result of increased temperature. Grains are often randomly oriented

Contact Metamorphism Draw a schematic picture of the process

Review Two of these rocks are igneous, 2 are metamorphic and one is sedimentary. Which rocks most likely metamorphic? Temperature A B C Depth E D

Examples of contact metamorphic Rocks Marble forms when limestone is heated Quartzite forms when sandstone is heated

Create a Concept Map Key Words: Linking phrases: regional metamorphism gneiss magma chambers contact metamorphism heat heat and pressure mountain belts grain size marble non-foliated rocks Linking phrases: surrounding can be formed by classified by caused by increasing that results in such as formed from an existing rock like associated with

Identify your metamorphic rocks