Normally a geothermal gradient increases in temperature with depth at about 30c per kilometer. Metamorphic petrology 1 metamorphic processes, contact, regional, t and p variations. Metamorphic rocks are best identified when looking at the rock as you see them in nature. Pdf stable isotope geochemistry of metamorphic rocks. The preexisting rocks may be igneous, sedimentary, or other metamorphic rocks.
Metamorphic petrology 2 metamorphic facies heat flow and heat production in crust. B relate plate tectonics to the formation of crustal features. Their study provides us with important data regarding formation of the earth and the past geological environment. The presence of index minerals in metamorphic rocks allows geologists to assess the temperatures and pressures the parent rock encountered. Metamorphic petrology 3 metamorphism of pelitic rocks minerals and isograds. One of the oldest types of rocks on our planet, metamorphic rocks are mainly formed due to changes in the parameters of temperature and pressure, which act on the parent material. Banding means that the rock consists of alternating, thin layers typically 1 mm to 1 cm of two different mineral compositions. They are formed when sedimentary and igneous rocks become changed by pressure and heat. One source of confusion is that we have both texture names and rock names, and although they often refer to the same thing, there are exceptions. Knowledge of metamorphic processes and rocks is valuable, because metamorphic.
This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. In many cases the bulk chemical composition of the rocks involved remains the same, such that the resultant change are in mineralogy and texture. Metamorphic rock names based on parent rock, geologic setting, and metamorphic grade. The domain of this classification system includes not only metamorphic rocks as commonly understood, but also a variety of hydrothermally altered, myloniteseries, cataclastic, and impact metamorphic rocks.
Metamorphism and metamorphic rocks chapter questions. Texture in metamorphic rocks individual minerals may or may not be bounded by crystal faces. Thus coarse grained metamorphic rocks involve long times of metamorphism. Note that classification is generally loose and practical such that names can be adapted to describe the rock in the most satisfactory way that conveys the important characteristics. These rocks with new texture and composition are metamorphic rocks. Because of how they are formed, metamorphic rocks constitute a great deal of the bedrock in earths crust. Apr 20, 2017 metamorphic differentiation rocks are inhomogeneous so is the deformation in rocks experiencing shear separation of high and low shear zones by transition zones. Metamorphic differentiation rocks are inhomogeneous so is the deformation in rocks experiencing shear separation of high and low shear zones by transition zones. Metamorphic rocks are usually highly deformed because they have been subjected to high temperature and pressure. Experiments suggest that the time involved is tens of millions of years. Mechanical deformation and chemical recrystallization are the two processes that affect rock during metamorphism. The rocks provide clues to their transformation into a metamorphic rocks. Metamorphic textures and mineralogy develop progressively over several hundreds of feetmeters of drilling. Metamorphic rocks are identified on these textures click image for large version, or go to metamorphic texture for more details.
Parent rocks the rock that the metamorphic rock comes from. A univariant assemblage f1 would be less likely to occur, and an invariant assemblage f0 would represent equilibrium at a fixed point in temperature and. Metamorphic settings b, r, s b, r, s s b, r, s b, r, s parent rock shale granite basalt chert sio2 limestone. Composition of metamorphic rocks and some aspects of evolution of.
Geochemistry of metamorphic rocks of the kurai block gorny altai article pdf available in russian geology and geophysics 554. Stages of metamorphism foliated rocks slate schist gneiss gneiss stripes. Classification of metamorphic rocks is based on mineral assemblage, texture, protolith, and bulk chemical composition of the rock. Note the strong vertical fabric of the canyon wall. Metamorphic petrology 4 pelites the akfm system continuous and. Metamorphic rocks are the third major type of rock, the other two being igneous and sedimentary. Pdf geochemistry of metamorphic rocks of the kurai block. Origin, texture, and classification of metamorphic rocks. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. Outline the role of volatiles in metamorphic processes. As per wikipedia, metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. Lecture notes metamorphism introduction metamorphism is a change of form that includes the growth of new minerals, typically in response to a rise in temperature and normally without the involvement of a magma. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of new minerals from old minerals. Metamorphism metamorphic environment is classified as regional, contact, dynamic, burial, hydrothermal, impact, metamorphism along fault zones.
Metamorphism and metamorphic rocks tulane university. Metamorphism is the addition of heat andor pressure to existing rocks, which causes them to change physically andor chemically so that they become a new rock. Hydrothermal metamorphism of mantle rock under a seafloor spreading center description. Geochemistry of metamorphic rock farhan farid r rock.
The chart below summarizes the parent rock, setting, and grade of common metamorphic rocks. Metamorphic rocks are formed deep within the earth when igneous or sedimentary rocks are changed under heat and intense pressure. In the large outcrop of metamorphic rocks in figure 1, the rocks platy appearance is a result of the process metamorphism. The heat and pressure cook the rocks changing their original structure considerably. Geochemistry of serpentinite muds and metamorphic rocks from the mariana forearc, odp sites 1200 and 778779, south chamorro and conical seamounts. The student knows that natural events can impact earth systems. The domain of this classification system includes not only metamorphic rocks as commonly understood, but also a variety of hydrothermally altered, myloniteseries, cataclastic, and impactmetamorphic rocks. All chapters of part ii of the book have been rewritten. Deep underground rocks are exposed to high pressures from the overlying layers of rocks and high temperatures from magma. To constrain the quantity of co2 released, fluiddriven reactions in metamorphic rocks can be studied by tracking fluidrock interactions along ancient fluid flow. Elsevier scientific publishing c o m p a n y, amsterdam o x f o r d n e w york coedition with academia, publishing house of the czechoslovak a c a d e m y of sciences, prague, 1983, 322 pp. Such features include folds, nappes, and faults with a wide variety of geometries. Metamorphic rocks metamorphic rocks are rocks from sedimentary and igneous origin that have been changed through high pressures and temperatures during orogenesis mountain building or during igneous intrusion contact metamorphism metamorphic rocks cont.
Proposals in this program generally address the petrology and hightemperature geochemistry of igneous and metamorphic rocks including mantle samples, mineral physics, economic geology, and volcanology. Generally, metamorphic grade is closely associated with the maximum temperature of metamorphism so that highergrade rocks have experienced higher. Read this sciencestruck article to gain extensive information about the main features of these rocks. Each of these will be discussed in turn, then we will summarize how metamorphic rocks are classified. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition. Naming metamorphic rocks once a root name is selected, then it may be pre. Classifying metamorphic rocks this system comes from the iugs subcommission on the systematics of metamorphic rocks scmr. Since new minerals are created during metamorphism, the end product metamorphic. B classify rocks as metamorphic, igneous, or sedimentary by the processes of their formation eighth grade scientific concept teks 9 earth and space. Grade of metamorphism metamorphic grade is a general term for describing the relative temperature and pressure conditions under which metamorphic rocks form. 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. Characteristics of metamorphic rocks science struck.
Studies of metamorphic rocks provide insights into the physical and chemical changes that take place deep within earth. Examples from cornwall that show the first tectonic and metamorphic fabrics in metasediments, plus a variety of sedimentary and igneous rock types in outcrop and hand specimen. Phyllosilicates accommodate better shear other minerals dissolve due to high shear. Right a metamorphic rock mylonite resulting from extreme deformation of granitic rocks. Metamorphism involves changes in mineral assemblage and rock texture and occurs in the solid state as a result of changes in temperature and pressure. Classification of metamorphic rocks depends on what is visible in the rock and its degree of metamorphism.
The mineral assemblages that occur in metamorphic rocks. Atlas of metamorphic minerals rockforming minerals of metamorphic rocks, in thin section a work in progress 1 olivine. This planar fabric is characteristic of many metamorphic rocks. Metamorphic grade is the extent or rank of metamorphism, measured by the amount of degree of difference between the parent rock and the metamorphic rock according to the agi glossary of geology. Normally, the two types of layers have the same kinds of minerals, but in different proportions, giving. There are a variety of processes involved, and they are collectively described by the term metamorphism. Explain what an open and closed metamorphic system is. Read this sciencestruck article to gain extensive information about the main. Metamorphism is the alteration of a preexisting rock the parent rock due to heat and pressure caused by burial in the earth.
The parent rock must adapt to the new conditions and it does so by changing mineral composition and texture. Pdf igneous and metamorphic complexes of the guiana. While it retains many aspects of the traditional classi. If the temperature of metamorphism is high enough for partial melting of the rock to occur, the changes would still be called metamorphism until the melt is. For example, if slate is exposed to higher temperature and pressure, it will become a rock called schist. We can measure the mineral compositions and assemblage i. Many precious materials, such as marble and many types of gemstones, including diamonds, are formed by the. We classify these compositegenesis rocks according to descriptive properties that reflect the multiple processes that make the rock composite. Rockforming minerals of metamorphic rocks, in thin section a work in progress 1 olivine. Metamorphic rocks in nature shale to slate metamorphism deformation of sedimentary rocks metamorphic rocks record how temperature and pressure affected an area when it was forming. Metamorphic rocks and plate tectonics greenschist facies upper continental crust in mountain ranges, and seafloor metamorphism of basalt amphibolite and granulite facies form progressively deeper in the roots of mountains contact metamorphic rocks form near igneous intrusions in mountain ranges. Purchase petrology of metamorphic rocks, volume 9 1st edition. Atlas of metamorphic minerals university of oxford. This is referred to as isochemical metamorphism, and the metamorphic system in this.
Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Geochemistry of metamorphic rock farhan farid r free download as word doc. If the schist is exposed to even higher temperature and pressure, it will become gneiss a different kind of gneiss than the granitic gneiss because slate is its. Mineral found in metamorphic rock formation environment. Metamorphic rock metamorphic rock structural features. Also, the chapters introduction and grade have undergone several major changes. If you think about it, in metamorphic rocks where temperature and pressure can both vary during metamorphism, the most likely case would be to find a divariant f2 assemblage of phases. The foliation is usually perpendicular to the direction of the applied stress. Metamorphic rocks are often intimately related to largescale kilometres of tens of kilometres structural features of earth. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineralrich fluids or, more commonly, some combination of these factors. For example, slate and marble are building materials, garnets are used as gemstones.
Ii origin, texture, and classification of metamorphic rocks teklewold ayalew encyclopedia of life support systems eolss some metamorphic rocks, particularly those buried to depths of several kilometers, contain numerous veins rich in quartz and feldspar. Mottled green color smooth, slick sides looks like squished watermelon seeds green, mottled, massive. Without careful examination by the geologist, and the recognition of the subtle changes in mineralogy and texture, much time and money can be wasted by drilling past the economic basement. Mineral prefixes first choose a general rock name using the guide above. Lpi educationpublic outreach cience ctivities ages. During metamorphism the protolith undergoes changes in texture of the rock and the mineral make.
Metamorphic rocks are classified according to their source rock type, structure, microstructure and mineral scheme for classification of igneous rocks and the. Combined geological and petrochemical data suggest that the lapland granulite belt can be divi ded into a lower sedimentaryvolcanic unit and an upper. Mathscience nucleus 2001 1 metamorphic rocks teacher guide including lesson plans, student readers, and more information lesson 1 formation of metamorphic rocks lesson 2 metamorphic rock classification chart lesson 3 metamorphic rocks lab lesson 4 the many facies of metamorphic rocks lesson 5 michelangelo and marble designed to be used as an. Igneous rocks as igneous rocks form out of magma and lava from the interior of the earth, they are known as primary rocks. Agents of metamorphism heat pressure chemical activity heat is the most important agent of metamorphism. In many cases, the correlation of metamorphic isograds and their position in the structure implies a genetic relationship. In many cases, the correlation of metamorphic isograds and their position in the structure implies a genetic. Foliation is common in aphanitic as well as phaneritic metamorphic rocks. Discuss the mode of occurrence and characteristic textures common in metamorphic rocks. Lightcolored dikes and sills of igneous rock cut the metamorphic rocks. Summarize the progression of different rock types produced by regional. Metamorphic comes from the greek word meta and morph, meaning change in form. Pdf geochemistry of serpentinite muds and metamorphic. Petrology of metamorphic rocks, volume 9 1st edition.
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