This property is very important to our interpretation of metamorphic rocks. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition. With more heat and pressure gneiss will begin to melt. Most metamorphic rocks have the same overall chemistry as the parent rock from which they formed this chemistry determines how the rock will change during metamorphism. By observing the mineral assemblage set of minerals within a metamorphic rock, it is. As strain increases, the foliation becomes more intense, and the minerals may sort themselves into thicker layers. Characteristics of sedimentary, igneous and metamorphic rocks. 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. The rocks provide clues to their transformation into a metamorphic rocks.
The properties of the metamorphic rock quartzite depend on the. Anisotropy of physical properties in metamorphic rocks. Metamorphism and metamorphic rocks tulane university. This lesson focuses on the properties of metamorphic rocks that help in its identification, most notably characteristics such as banding and foliation. Metamorphic rocks are formed deep within the earth when igneous or sedimentary rocks are changed under heat and intense pressure. Physical properties of rocks, 2nd edition, describes the physical fundamentals of rock properties, based on typical experimental results and relevant theories and models. Metamorphic rocks were once igneous or sedimentary rocks, but have been changed metamorphosed as a result of intense heat andor pressure within the earths crust. Metamorphic rocks form when existing sedimentary or igneous rocks get heated to the extent that the existing minerals start to recrystallize into new minerals. Most metamorphic rocks are comprised of the relatively insoluble silicate minerals. 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. 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. They are crystalline and often have a squashed foliated or banded texture. For example, slate and marble are building materials, garnets are used as gemstones. All civil engineering structures are built on rock so, engineering properties of rocks are very much important.
The x axis is temperature in celsius and the y axis is kilometers below the surface. The color of a rock describes the hue or tone of the rock. Metamorphic textures and mineralogy develop progressively over several hundreds of feetmeters of drilling. Generally, metamorphic grade is closely associated with the maximum temperature of metamorphism so that highergrade rocks have experienced higher. Slate is made of finegrained interlocking crystals which lie flat in the same direction, known. Explain what an open and closed metamorphic system is.
There is also an exploration of the properties of contact metamorphism, a process of baking the rock from nearby intrusions that result in low to midgrade metamorphism. Some sandstones are made almost entirely of quartz sand grains. The properties of the metamorphic rock quartzite depend on the properties of its parent rock, sandstone. The two characteristics used to classify metamorphic rocks are foliation and lineation.
Metamorphic rocks were once igneous or sedimentary rocks, but have been changed metamorphosed as a result of intense heat andor pressure within the. This second set of lecture notes focuses on physical properties such as weathering potential, slaking potential, swelling potential, hardness, abrasiveness, and other properties such as porosity, density, water content, etc. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. When sedimentary rocks or igneous rocks go through the physical process such as pressure exposure, heat changes, and tectonic plate movement at plate edges. Studies of metamorphic rocks provide insights into the physical and chemical changes that take place deep within earth. Under heat and pressure, the spaces between the sandstones grains are filled, and the rock recrystallizes into quartzite. At this point in your course, you should appreciate that rock properties tend to vary widely, often over short distances. Under greater heat and pressure, as metamorphic minerals such as mica and feldspar begin to form, strain orients them in layers.
Start studying characteristics of sedimentary, igneous and metamorphic rocks learn vocabulary, terms, and more with flashcards, games, and other study tools. Discuss the mode of occurrence and characteristic textures common in metamorphic rocks. The foliation is usually perpendicular to the direction of the applied stress. It provides readers with all relevant rock properties and their interrelationships in one concise volume. Figure 3 classification scheme for metamorphic rocks. Metamorphic rocks are best identified when looking at the rock as you see them in nature. Rocks of the earth their composition and classification 5 1. Physical properties of rocks, volume 8 1st edition. Also, the chapters introduction and grade have undergone several major changes. 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. The cookbook for making metamorphic rock starts by partially melting the ingredients in this.
Zoback a,1, abbas khaksar b,2 a department of geophysics, stanford university, palo alto, ca 943052215, usa b geomechanics international, inc. Experiments suggest that the time involved is tens of millions of years. Empirical relations between rock strength and physical. The resulting rocks are generally finegrained and lack attitudinal features.
Models as a basis for rock physics theories an overview 16. Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. In the large outcrop of metamorphic rocks in figure 1, the rocks platy appearance is a result of the process metamorphism. The velocity of elastic waves has been measured along the principal fabric directions in 110 alpine rocks, and these data are analyzed in conjunction with previously measured data on density, porosity, specific heat, and thermal diffusivity for the same rocks. A corollary of this is that during engineering practice, the penalties for geologic mistakes can be severe. Ii origin, texture, and classification of metamorphic rocks teklewold ayalew encyclopedia of life support systems eolss as on the properties of the country rock. These rocks are identified by the presence of certain mineral types and specific textures. This planar fabric is characteristic of many metamorphic rocks.
Also, a dark piece of glass may appear to be opaque if it is thick enough. A striped pattern, for example, may be used to describe a. Outline the role of volatiles in metamorphic processes. Some types of metamorphic rocks, such as quartzite and marble, which also form in directedpressure situations, do not necessarily exhibit foliation because their. Field description of metamorphic rocks the basic procedural aspects of writing a description for metamorphic rocks or rock units are identical to those for sedimentary rocks and rock units. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 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. Metamorphic rocks metamorphic rocks are formed when rock changes over a period of time due to a lot of physical changes like pressure, heat and different chemical activity. Remember that glass can be almost any color, including black, so dont be fooled by the color. 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. A new approach for estimation of properties of metamorphic rocks. Because of how they are formed, metamorphic rocks constitute a great deal of the bedrock in earths crust.
Summarize the progression of different rock types produced by regional. Black, red, green or blue may be used to describe the color. There is also an exploration of the properties of contact metamorphism, a process of baking the rock from nearby intrusions that. Metamorphic rocks types and properties of metamorphic rocks. Results of experimental investigations an overview 15 1. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of.
A new approach for estimation of properties of metamorphic. Physically detennined classification of rocks 12 1. Metamorphic rocks are the third major type of rock, the other two being igneous and sedimentary. Microstructure, filtration, elastic and thermal properties of granite rock samples. 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. For this purpose a companion web site contains a selection of model based equations. The presence of mineral layers, called foliation, is an important feature for classifying metamorphic rocks. Metamorphic rocks are those formed by other types of rocks that have been exposed to heat, pressure and time, which change them into a different type of rock. Classification of rocks and description of physical properties of rock introduction uniformity of definitions, descriptors, and identification of rock units is important to maintain continuity in geologic logs, drawings, and reports from a project with multiple drilling sessions, different loggers and. Increasing effect of metamorphism on rock properties. Their study provides us with important data regarding formation of the earth and the past geological environment. What are some properties of metamorphic rocks answers. Variability of intact rock mechanical properties for some metamorphic rock types and its implications on the number of test specimens article in bulletin of engineering geology and the environment. We can measure the mineral compositions and assemblage i.
Igneous rocks form from magma, which is not a rock since it is a fluid and sedimentary rocks lithify from loose sediment or precipitate from a solution. Mineral properties revised on 8272012 page 3 of vitreous lusteris like that of glass, shiny and translucent to transparent. These properties make it useful for a wide variety of architectural, practical, and artistic uses. Grade of metamorphism metamorphic grade is a general term for describing the relative temperature and pressure conditions under which metamorphic rocks form.
Characteristics of metamorphic rocks science struck. Variability of intact rock mechanical properties for some. Igneous rocks as igneous rocks form out of magma and lava from the interior of the earth, they are known as primary rocks. Pdf on jun 1, 2018, zozk abdaqadir and others published physical and mechanical properties of metamorphic rocks find, read and cite all the research you need on researchgate. The presence of index minerals in metamorphic rocks allows geologists to assess the temperatures and pressures the parent rock encountered. During metamorphism the protolith undergoes changes in texture of the rock and the mineral make. The original rock is subjected to heat temperatures greater than 150 to 200 c and pressure 100 megapascals 1,000 bar or more, causing profound physical or chemical change. Metamorphic rocks pictures of foliated and nonfoliated types. Effect of compositional and 255 structural variations on log responses of igneous and metamorphic rocks. Rocks have very much importance in engineering point of view. Physical properties of rocks, volume 65 2nd edition.
Many precious materials, such as marble and many types of gemstones, including diamonds, are formed by the metamorphic process. All chapters of part ii of the book have been rewritten. Knowledge of metamorphic processes and rocks is valuable, because metamorphic. The heat and pressure cook the rocks changing their original structure considerably. Classification of rocks and description of physical properties of rock introduction uniformity of definitions, descriptors, and identification of rock units is important to maintain continuity in geologic logs, drawings, and reports from a project with multiple drilling sessions, different loggers and mappers. A brief geology of the study area is described in order to provide the background for the metamorphic implication of the influence of the mafic intrusion of the bushveld igneous complex into the transvaal supergroup in south africa on the properties of the host rocks.
This work therefore studied the metamorphic effect of ultramafic and mafic magma intrusion of the bushveld complex, into the transvaal supergroup on the properties of rocks in the immediate vicinity and progressively away from the source of intrusion to the lower southern part of kalahari basin in south africa which appears to be relatively. 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. Thus coarse grained metamorphic rocks involve long times of metamorphism. Empirical relations between rock strength and physical properties in sedimentary rocks chandong chang a. Origin, texture, and classification of metamorphic rocks. The protolith may be a sedimentary, igneous, or existing metamorphic rock. A workbook is a symbiosis of a brief description of physical fundamentals of rock properties based on typical experimental results and relevant theories and models with a guide for practical use of different theoretical concepts. 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. For this purpose a companion web site contains a selection of model based equations in excel worksheets for practical application and. Ppt engineering properties of rocks powerpoint presentation.
However, metamorphic rocks can form from metamorphic parent rocks as well. It is composed primarily of the mineral calcite caco 3 and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite. 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. Note the strong vertical fabric of the canyon wall. C thermal properties thermal expansion, conductivity, and c in situ stresses. Metamorphic rocks can be formed from sedimentary, igneous and even other metamorphic rocks.
The texture of some rocks can be determined by looking at the rock as well as feeling it. For example, if slate is exposed to higher temperature and pressure, it will become a rock called schist. 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. Almost invariably this leads to the development of interlocking textures with low porosities. Smooth, rough, hard or soft are common descriptions. Slate tends to break into flat sheets or plates, a property described as slaty cleavage. Pdf physical and mechanical properties of metamorphic rocks. Metamorphic rock definition and limits including hydrothermally. Read this sciencestruck article to gain extensive information about the main features of these rocks. Since new minerals are created during metamorphism, the end product metamorphic. The five physical properties of rocks are color, luster, shape, texture and pattern. 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 separated from its. This rock is therefore half igneous and half metamorphic.