The characteristic contact metamorphic effects produced around an igneous intrusion, the formation of metamorpic zones and associated rock types that are formed in contact metamorphism environment will be discussed here below. Igneous and sedimentary rocks both have the potential to become a metamorphic rock. Rocks are classified into three distinct groups igneous, sedimentary, and metamorphic and each is discussed in a separate section. Ordinarily a finegrained, compact rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock and classified as a metamorphic rock.
Metamorphic rocks contain regular layers of crystals that sometimes have a wavy or zigzag arrangement. Rock and mineral identification for engineers fhwa us. Gneiss is formed from another metamorphic rock called schist. Finally, students may need their earth science reference tables esrt for parts of the lesson a document used widely in the new york state earth science. Metamorphic rocks form at higher temperatures and pressures than sedimentary rocks. Metamorphic rocks can form in different conditions, in different temperatures up to 200 c and pressures up to 1500 bars. The synthetic investigation of rocks proceeds by experimental work that attempts to reproduce different rock types and to elucidate their origins and structures. Metamorphic rocks metamorphic rocks are formed by great heat and pressure. The two major factors that influence the development of metamorphic rocks are heat and pressure. Formation of metamorphic rocks macomb science olympiad. Pdf petrogenesis of metamorphic rocks, 8th edition. These rocks were once igneous or sedimentary rocks.
A metamorphic rock bsedimentary rock cigneous rock dvolcanic rock 2. Rocks are an aggregate of one or more minerals held together by chemical bonds. Formed by modification of previously existing rocks by the application of heat and or pressure within the earth. Rocks that form from the cooling of magma below the earths crust or lava are called igneous rocks. Metamorphic rocks formation,classification, type, distribution slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. This worksheet has 22 short answer questions about metamorphic rock diagrams and graphs. Because the dark colored minerals tend to form elongated crystals, rather than sheet like crystals, they still have a preferred orientation with their long directions perpendicular to the maximum differential stress. These are the rocks that form by the effects of heat, pressure, and shear upon igneous and sedimentary rocks. Heat and pressure without melting change rocks, forming metamorphic rocks. Relevant vocabulary is also listed on each learning activity page. Formation of the san andreas fault system through time from this dynamic earth modified from usgs.
They are subject to forces from the huge weight of soil, sediments and other rocks. Metamorphic processes generally cannot be observed directly. Metamorphic rock such as gneiss, phyllite, schist and slate which have a layered or banded appearance that is produced by exposure to heat and directed pressure. Metamorphic rocks rocks ks3 chemistry revision bbc. These dark colored minerals tend to become segregated into distinct bands through the rock this process is called metamorphic differentiation, giving the rock a gneissic banding. They are generally found inside the earths crust where there is enough heat and pressure to form the rocks. Metamorphic rocks and processes metamorphism comes from the greek words meta change morphe form metamorphic rocks form by solidstate no melting transformation of preexisting rock by processes that take place beneath earths surface. Most metamorphic rocks are ls tectonites that form from a more general strain history. The recrystallization of unmelted material under high temperature and pressure results in aslate bdunite cgneiss dquartzite 3. Access the answers to hundreds of metamorphic rock questions that are explained in a way thats easy for you to understand.
This classification is based on the mode or process of formation of a rock. For example, shale, a sedimentary rock, can be changed, or metamorphosed, into a metamorphic rock. Depending on the way a rock has formed it will belong to one of these groups. Rocks with purely planar fabrics are called s tectonites and form by a flattening deformation oblate strain ellipsoid. Rocks are classified into three distinct groups based on how they are formed. The lunar highlands are formed of anorthosite, an igneous rock predominantly of calciumrich plagioclase. Formation of metamorphic rocks metamorphic rocks have been changed by heat, and or pressure metamorphic rocks can originate from any other type of rock the original rock type is called the parent rock.
They are subject to forces from the huge weight of soil, sediments and other rocks above them. As per wikipedia, metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. Rock formed by high temperatures and pressures that cause changes in the parent rock while in the solid form. Metamorphic rocks sometimes show distortions caused by the movements that led to their formation. Some form during mountainbuilding by forces of others from the heat of igneous intrusions in regional metamorphism others from the heat of igneous intrusions in contact metamorphism. A rock or a rock complex may bear the effects of more than one metamorphic event e. They are not made from molten rock rocks that do melt form igneous rocks instead.
Most commonly used to describe lowgrade micaceous pelitic rocks such as. Feldspar and quartz are the most common minerals found in rocks. Interaction between metamorphic petrologists and geophysicists in the 1980s led to the realization that each metamorphic rock follows its own unique path through pressure depth temperature space during metamorphism and that these paths bear little or no resemblance to steadystate geotherms. Metamorphism and metamorphic rocks rocks created by heat, pressure andor chemically reactive fluids metamorphic rocks are produced from igneous rocks sedimentary rocks other metamorphic rocks 2. The preexisting rocks may be igneous, sedimentary, or other metamorphic rocks. This may give rise to wavy or zigzag patterns within the rock. Rocks and geology in the san francisco bay region usgs. Deposits of dead plants and animals are also called sediments. Metamorphic rocks are an important topic in geology.
A brief introduction to metamorphic rocks including a look at how they form as a result of exposure to intense heat andor pressure. Metamorphic rocks metamorphic rocks are the result of the transformation of a preexisting rock type, the protolith, in a process called metamorphism, which means change in form. Which metamorphic rock will have visible mica crystals and a foliated texture. Most metamorphic rocks formed by regional metamorphism have aligned crystals but some thermal metamorphic rocks have randomly orientated crystals was this rock metamorphosed by regional or thermal contact metamorphism. Barriers to college students learning how rocks form eric. Forms when rocks are changed into different kinds of rocks by great heat andor pressure they are heated, squeezed, folded, or chemically changed by contact with hot fluids andor tectonic forces. Formation of metamorphic rocks how they are formed igneous, sedimentary and metamorphic rocks can become buried below the earths surface, owing to the movements of the earths plates. Igneous rocks form when magma, molten rock, rises upward. In nature, there are different types of rocks available, i. Metamorphic rocks are formed under the surface of the earth from the metamorphosis change that occurs due to intense heat and pressure squeezing. Metamorphic rocks form at lower temperatures than igneous rocks. Sediments produced by weathering and erosion form sedimentary rocks through the process of lithification.
Metamorphic rocks may eventually be heated enough to melt, forming a new generation of igneous rocks. The rocks that result from these processes often have ribbon like layers and may have shiny crystals, formed. Types of rock and their formation earths crust is composed of rocks. However, feldspar and quartz are the most common minerals found in rocks. Sedimentary and metamorphic rocks notes can be accessed on notes section of website 6. Metamorphic rock, any rock that results from the alteration of preexisting rocks in response to changing conditions, such as variations in temperature, pressure, and mechanical stress, and the addition or subtraction of chemical components. Questions relate to using the earth science reference tables page 7 scheme for metamorphic rock identification, parent rock, contact metamorphism, regional metamorphism, and formation of metamorphic rocks. They are original rock made by magma that becomes trapped and cools. During metasomatism the rock remains in a solid state. Slate is a metamorphic rock that is formed from the sedimentary rock mudstone.
Theyre all connected to the endless rock cycle, moving from one type to a different and dynamic form, texture and even chemical composition of the method. Sedimentary rocks are formed from weathered and cemented pieces of other rocks. Have students bring in rocks they have found to show the class. Eighth grade lesson metamorphic rocks i betterlesson. Rocks do not have definite composition of mineral constituents. Metamorphic rocks are usually denser and harder than sedimentary rocks. Metamorphic rock, as its name suggests, is a rock that has changed form. Metamorphic rock metamorphic rock pressuretemperaturetime paths. Metamorphic rocks are rocks that have morphed into another kind of rock.
Igneous rocks that formed deep below the surface of the earth as the magma forced its way into the crust are termed intrusive rocks. Comparing metamorphic, igneous, and sedimentary rocks. Elements such as oxygen, and compounds like silica, magnesium, iron, aluminum and calcium fuse igneous rock into other forms called metamorphic rock. Rock formation 19th century efforts to synthesize rocks. The heat and pressure can change the composition and appearance of the minerals in rocks. Metamorphic rocks are often made from other types of rock. The breakdown products are deposited to form sedimentary rocks. Mylonite is ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones. Metamorphic rock is rock that has been created by the transformation of igneous rock. The protolith is subjected to heat greater than 150 degrees celsius andor extreme pressure causing profound physical andor chemical change.
Monometamorphism is a metamorphism resulting from one metamorphic. By being b uried deep enough for a long enough time, a rock will. The schist formed from fine grained sedimentary rocks often shale. Each rock group is further subdivided into subgroups that are defined by the mode of origin of the rocks.
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