Rocks change due to heat, weatheringerosion, and cooling, and pressure earth is like one big rock recycling machine. Igneous and metamorphic rocks of the serpentine hot springs. The third major rock type is metamorphic, meaning that the rocks have been changed. The presence of index minerals in metamorphic rocks allows geologists to assess the temperatures and pressures the parent rock encountered. Since new minerals are created during metamorphism, the end product metamorphic. However, metamorphic rocks can form from metamorphic parent rocks as well. Identify major minerals contained within a metamorphic rock. Metamorphism is the change of minerals or geologic texture distinct arrangement of minerals in preexisting rocks, without the protolith melting into liquid magma a solidstate change. 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. 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. We classify these compositegenesis rocks according to descriptive properties that reflect the multiple processes that make the rock composite. 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.
The protolith may be a sedimentary, igneous, or existing metamorphic rock. Petrophysics of the metamorphic and igneous rocks day 1 1 overview to igneous and metamorphic rocks terminology, main rock types, mineralogy, geochemistry, genetic evolution, fabric and structure, types of alteration 2 overview to the petrophysical characteristics of crystalline rocks. Seen on a global scale they constitute the dominant material of the earth. Metamorphic textures and mineralogy develop progressively over several hundreds of feetmeters of drilling. Lightcolored dikes and sills of igneous rock cut the metamorphic rocks. The diagrams help to determine the pressure and temperature conditions under which a given set of metamorphic rocks may have formed. Normally a geothermal gradient increases in temperature with depth at about 30c per kilometer. The original rock, or protolith, is subjected to heat and pressure which cause physical, chemical and mineralogical changes to the rock. Petrogenesis of metamorphic rocks by bucher, kurt, 1994, springerverlag edition, in english 6th ed. Summarize the progression of different rock types produced by regional. This planar fabric is characteristic of many metamorphic rocks.
Classification of metamorphic rocks metamorphic rocks are classified on the basis of texture and composition either mineralogical or chemical unlike igneous rocks, which have been plagued by a proliferation of local and specific names, metamorphic rock names are. Note the strong vertical fabric of the canyon wall. Thus coarse grained metamorphic rocks involve long times of metamorphism. Petrogenesis of metamorphic rocks kurt bucher, martin. Products subcommission on the systematics of metamorphic. Metamorphic rocks are usually highly deformed because they have been subjected to high temperature and pressure. Metamorphic rocks are best identified when looking at the rock as you see them in nature. The chemical components and crystal structures of the minerals making up the rock may change even. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and. Phyllosilicates accommodate better shear other minerals dissolve due to high shear.
For example, if slate is exposed to higher temperature and pressure, it will become a rock called schist. The lab is designed to model the methodology involved in describing a metamorphic thinsection thoroughly, thereby allowing you to name rock and interpret its history or mineral growth paragenetic sequence. 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. 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. Origin, texture, and classification of metamorphic rocks. Petrogenesis of metamorphic rocks kurt bucher springer. Agents of metamorphism heat pressure chemical activity heat is the most important agent of metamorphism. The mineral paragenesis and metamorphic reactions described for carbonatesilicate rocks and impure marbles indicated that both group of rocks represent metamorphic product of marls andor silt. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. Generally, metamorphic grade is closely associated with the maximum temperature of metamorphism so that highergrade rocks have experienced higher. 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. Knowledge of metamorphic processes and rocks is valuable, because metamorphic. Sedimentary and metamorphic rocks notes can be accessed on notes section of website 6.
Schmid, r, fettes, d, harte, b, davis e, desmons, j. Petrogenesis of metamorphic rocks 1994 edition open. Students examine trays of metamorphic rocks and minerals and record their physical properties, composition, and habit. In this threepart exercise, students study hand samples and thin sections of important metamorphic rocks and minerals. This confining pressure increases in proportion to the depth of burial. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Experiments suggest that the time involved is tens of millions of years. Metamorphic rocks, including gneiss and marble, change when extreme heat and pressure cause mineral changes through recrystallization. Gallery of photographs of highgrade metamorphic rocks.
Metamorphic rocks are formed through the transformation of preexisting rocks in a process known as metamorphism meaning change in form. Explain what an open and closed metamorphic system is. 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 systematically change their mineralogical composition as a result of tectothermal events. Classification classification of metamorphic rocks depends on what is visible in the rock and its degree of metamorphism. A classification and glossary of terms recommendations of the international union of geological sciences subcommission on the systematics of metamorphic rocks many common terms in metamorphic petrology vary in their usage and meaning between countries, and there is a range of specialized rock names that have been applied locally. At great depths, the pressure is sufficient to cause recrystallization along grain boundaries, but because confining pressure is the same in all directions, mineral grains grown under these conditions of uniform stress do not have a preferential growth direction. Outline the role of volatiles in metamorphic processes. Mcdermott the basic terminology of igneous petrology.
Title slide of metamorphic rocks slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. It is suitable as a text for serious, nononsense, onesemester undergraduate course in metamorphic petrology. 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 electronic textbook. The rocks provide clues to their transformation into a metamorphic rocks. The rock cycle it is how earth changes one type of rock into another type of rock.
The iugs mineralogical based classification and nomenclature scheme for phaneritic and aphanitic igneous rocks. Together, we will go through the following essential steps for a complete petrographic description of a metamorphic rock. Mechanical deformation and chemical recrystallization are the two processes that affect rock during metamorphism. Sedimentary rocks form when these layers of sediment are pressed together until they harden into rock.
Many of the minerals in metamorphic, or changed, rocks are the same silicates, carbonates, etc. Petrogenesis of metamorphic rocks presents a large number of diagrams. By and large, it is precise and accurate, clearly written, logically organized and well focused. 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. Crystalline limestone is a rock that results from the crystallization of the calcite in sedimentary limestone. Discuss the mode of occurrence and characteristic textures common in metamorphic rocks. During metasomatism the rock remains in a solid state. The understanding of the petrogenesis and significance of metamorphic of geological education. 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. All of these processes combine to make the rock cycle.
The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form. High pt metamorphic rocks 1brecommendations by the iugs subcommission on the systematics of metamorphic rocks. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of. High pt metamorphic rocks british geological survey. Classification and nomenclature of igneous rocks prof. Ii igneous and metamorphic petrology angelo peccerillo encyclopedia of life support systems eolss since average geothermal earth gradient is about 30 c km1, it can be deduced easily that most of the rocks forming the crust and mantle are indeed metamorphic. 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. Grade of metamorphism metamorphic grade is a general term for describing the relative temperature and pressure conditions under which metamorphic rocks form. 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. Geology of the north cascades scenic metamorphic rocks. 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 rocks are one of the three classes of rocks.
Petrogenesis of metamorphic rocks presents a large number of diagrams showing the stability relations among minerals and groups of minerals found in metamorphic rocks. 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. Metamorphism involves changes in mineral assemblage and rock texture and occurs in the solid state as a result of changes in temperature and pressure. The outstanding feature of the 7th edition of this book is the large number of phase diagrams showing the stability relations among minerals and groups of minerals found in metamorphic rocks. Studies of metamorphic rocks provide insights into the physical and chemical changes that take place deep within earth. Petrogenesis of metamorphic rocks 8th edition request pdf. International listing of research groups working on metamorphic rocks and processes. Petrogenesis of metamorphic rocks is, like the preceding six editions, a fine and important book. 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. 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. Metamorphic differentiation rocks are inhomogeneous so is the deformation in rocks experiencing shear separation of high and low shear zones by transition zones. Also, the chapters introduction and grade have undergone several major changes. Classification of metamorphic rocks depends on what is visible in the rock and its degree of metamorphism. Metamorphic rocks make up the largest volume of the earth.
All chapters of part ii of the book have been rewritten. Concise information about metamorphic processes, with excellent cartoon of mineral growth during compression. 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. Sediments produced by weathering and erosion form sedimentary rocks through the process of lithification. Metamorphic rocks can change into another metamorphic rock. 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. The entire package includes the programs, gibbs, gtb, plus tutorial notes pdf format for.
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