Metamorphism of mafic rocks first evident in the greenschist facies, which correlates with the chlorite and biotite zones of the associated pelitic rocks ftypical minerals include chlorite, albite, actinolite, epidote, quartz, and possibly calcite, biotite, or stilpnomelane fchlorite, actinolite, and epidote impart the green. Quantifying the tectonometamorphic evolution of pelitic rocks from a. This lab assignment helps students to develop a detailed understanding of afm diagrams and how they relate to pressuretemperature conditions of metamorphism of pelitic rocks. Lecture eight metamorphism of pelitic rocks metapelites 1 lecture eight metamorphism of pelitic rocks metapelites part i 2 what is the metapelites. Also, the chapters introduction and grade have undergone several major changes. Appendix b classification of metamorphic and other compositegenesis rocks, including hydrothermally altered, impactmetamorphic, mylonitic, and cataclastic rocks, version 1. Keywords petrography, sealyham, asaphus, abergwilli, abermawr. Quantifying the tectonometamorphic evolution of pelitic rocks from a wide range of tectonic settings. By and large, it is precise and accurate, clearly written, logically organized and well focused. 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.
This was followed by a somewhat higherpressure metamorphism, m 3, involving staurolitechlorite and sillimanite. Pdf progressive metamorphism of pelitic rocks from the. The foliations in these rocks generally dip steeply to the southeast. A process of change 1 metamorphic rock forms from a preexisting rock or protolith. Moreover, compositions of coexisting minerals show regular variation with imposed. In the late 1800s and early 1900s, george barrow discovered the classic barroviantype metamorphic sequence in the southeastern scottish highlands. Metamorphic evolution of pelitic rocks of the monte rosa nappe. Quizlet flashcards, activities and games help you improve your grades.
Find materials for this course in the pages linked along the left. Progressive metamorphism of pelitic and quartzofeldspathic. Metamorphism, fluid flow and partial melting in pelitic. Figure 6 shows metamorphic rock names in relation to protolith and grade of metamorphism. Pelitic definition of pelitic by the free dictionary. The term pelitic rocks is used to signify all slaty or schistose rocks. Field, petrologic and geochemical data were used to characterize fluid infiltration and partial melting during metamorphism of pelitic rocks in the contact aureole of the onawa pluton, central maine, usa. Prograde polyphase regional metamorphism of pelitic rocks, nw of jamshedpur, eastern india. Metamorphic rocks formed in the shallow crust are referred to as lowgrade metamorphic rocks. Calculated mineral stabilities for an average pelitic rock over a pressuretemperature pt range appropriate for normal. Association of the metamorphism of pelitic rocks with migmatites pelitic rocks are derived from clayrich sediment and are of particular importance in metamorphism because they develop a wide range of distinctive minerals.
What is a metamorphic facies and what is the concept used for. It represents a common type of regional pelitic orogenic metamorphism. Barrovian metamorphism is widely found across time and space on all parts of the earth, and produces the most common metamorphic rocks. 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. Multistage metamorphism of the uhp pelitic gneiss from the southern altyn tagh hpuhp belt, western china. As a current student on this bumpy collegiate pathway, i stumbled upon course hero, where i can find study resources for nearly all my courses, get online help from tutors 247, and even share my old projects, papers, and lecture notes with other. Pdf metamorphic evolution of pelitic rocks of the monte. The word metamorphism comes from ancient greek words for change meta and form morph. The term was earlier used by geologists to describe a clayrich, finegrained clastic sediment or sedimentary rock, i. Pdf contact metamorphism in pelitic rocks on the island of. Pelitic rocks are slates or phyllites and typically.
Petrogenesis of metamorphic rocks kurt bucher, martin frey. For example, staurolitebearing assemblages in pelitic rocks develop in the amphibolite facies, and thus are consistent with hornblendeplagioclase assemblages but not actinolitechlorite assemblages in interlayered mafic rocks. A complete barrovian sequence ranging from unmetamorphosed shales to sillimanitek. Pdf progressive metamorphism of pelitic rocks from. He observed that as a pelitic rock undergoes higher pressures and temperatures, its mineral assemblage changes from predominantly chlorite to biotite to.
Contact metamorphism in pelitic rocks on the island of kos greece, eastern aegean sea. Petrographic analysis of igneous and metamorphic rocks from. Amphiboles occur in contact metamorphic aureoles around igneous intrusions. Orthorhombic systemorthorhombic crystals commonly twin on planes parallel to a. In pelitic rocks, barrow recognized 6 zones of distinctive mineral assemblages, which he recognized as representing increasing grade of.
Metapelites are probably the most distinguished family of metamorphic rocks. 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. The list of counties below link to pdf files of corresponding county rocktype maps. Other articles where contact metamorphism is discussed. Atlas of metamorphic minerals university of oxford. Nonfoliated rocks are given specific names based on their mineralogy and composition. Constraints from petrology and single grain monazite age data.
Metamorphism of basic and pelitic rocks at sulitjelma, norway. The most important sedimentary protoliths are pelitic claystones, quartzofeldspathic, carbonate rocks and mixtures of the three groups, such as marls carbonaterich pelitic sediments to clayrich carbonates. 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. The fate of graphite in prograde metamorphism of pelites. Origin, texture, and classification of metamorphic rocks. Have student groups examine rocks in their kits and find those. Due to the very common presence of smectite in early diagenesis of pelitic sediments and. The contact aureoles produced in siliceous limestones and dolomites. Metamorphism of pelitic rocks metapelites springerlink.
Regional thermal metamorphism and deformation of the sitka. Guroorrr, department of geologicol sci,ences, ll niv er s ity of c alif or ni a, d aai s, c olij or ni a. Quantifying the tectonometamorphic evolution of pelitic. Gnnnn, department oj geol,ogy, uniaersity oj minnesota, dulwth, minn,esota. Evidence for major mass transfer and volume strain during. Statistical analysis of the data shows that barrovian zone metamorphism of pelitic schist generally causes increases in the whole rock concentrations of the lowsolubility elements ti and all the observed increases in ti and al contents as. Classification and nomenclature of igneous rocks prof. This is why we say that the changes are solid state. Aphebian metapelites and quartzofeldspathic rocks from the grenville province south of the labrador trough display progressive changes in mineral assemblages as a result of grenvillian metamorphism, consistent with variation in grade from greenschist to upper amphibolite facies. Modeling prograde tio 2 activity and its significance for. Review naming metamorphic rocks what is the difference.
Over millions of years, these metamorphic rocks have come to the. 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. Igneous and metamorphic petrology flashcards quizlet. During metamorphism, new minerals grow at the expense of old minerals, andor the shape, size, and arrangement of grains in the rock may change. Progressive metamorphism of pelitic rocks from protolith to granulite facies, dutchess county, new york, usa. Petrogenesis of metamorphic rocks kurt bucher springer. Typical examples include characteristic rocks and minerals such as chloritekyaniteschist, staurolitegarnet micaschist, chloritoidgarnet micaschist, kyanitestaurolite schist, biotitegarnetcordierite gneiss, sillimanitebiotite gneiss and orthopyroxenegarnet granulite. Progressive metamorphism of pelitic rocks from greenschist to upper amphibolite facies in the area around kandra, saraikelakharsawan district, jharkhand conference paper pdf available. A metamorphic rock which has experienced a temperature of 600c and a pressure of 600mpa is termed a highgrade metamorphic rock. Mcdermott the basic terminology of igneous petrology. 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. After a lowgrade metamorphism, m 1, the region suffered a highergrade early metamorphism, m 2, which in many places produced andalusite and cordierite as well as staurolite. You should know all about sedimentary, igneous and metamorphic rocks, so have a look at these pictures and see if you can identify each specimen. Progressive metamorphism of pelitic rocks from protolith to granulite.
The chemical components and crystal structures of the minerals making up the rock may change even. Metamorphic rocks never melt if they did they would become igneous magma. They systematically change their mineralogical composition as a result of tectothermal events. Multistage metamorphism of the uhp pelitic gneiss from. If retrograde metamorphism were a common process then upon uplift and unroofing metamorphic rocks would progressively return to mineral assemblages stable at lower pressures and temperatures. Calculations show that the patterns are consistent with partial melting of pelitic rocks from which a granitic low temperature portion has been removed by anatexis to produce a restite containing the observed geochemical variations. 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.
Interaction between metamorphism and deformation part 12. Introductory phase equilibria and thermodynamics part 5. Metapelite phase equilibria mineralogical society of america. Barrovian metamorphism is the most commonly encountered. Metamorphic rock metamorphic rock pressuretemperaturetime paths. We have already discussed the facies concept and done a lab on mafic rocks by the time we get to this assignment. Twinning, polymorphism, polytypism, pseudomorphism page 1of. Symmes gh, ferry jm 1992 the effect of whole rock mno content on the stability of garnet in pelitic schists during metamorphism. Braveno law 021 forms a contact twin in the mineral orthoclase. A regional study of metamorphosed pelitic rocks in. Metamorphic rock metamorphic rock metamorphic facies. Amphibolite these rocks are dark colored rocks with amphibole usually hornblende as their major mineral. Again, this discussion and classification applies only to rocks that are not produced by highstrain metamorphism. I introduce the laboratory assignment via a powerpoint presentation that is available from the teaching petrology website.
Metamorphic rocks may change so much that they may not resemble the original rock. Chondrite normalized ree patterns are characterized by fanning light and heavy ree variations. The iugs mineralogical based classification and nomenclature scheme for phaneritic and aphanitic igneous rocks. Yet, high grade metamorphic rocks are common at the surface of the earth and usually show only minor retrograde minerals. Metastable persistence of pelitic metamorphic assemblages at. Characteristics of metamorphic rocks a metamorphic rock used to be some other type of rock, but it was changed inside the earth to become a new type of rock.
All chapters of part ii of the book have been rewritten. Minerals definition, types, and identification department. Chapter 7 metamorphism and metamorphic rock flashcards. Show the class a video, or look at books or posters that show weathering, erosion and sedimentary rocks. 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. It is suitable as a text for serious, nononsense, onesemester undergraduate course in metamorphic petrology. Metamorphic rocks make up the largest volume of the earth. It is a metamorphic grade transitional between zeolite facies and greenschist facies representing a temperature range of 250 to 350 c and a pressure range of approximately two to seven kilobars. The metasedimentary rocks consist mainly of an arenopelitic. Metamorphism of the pelitic rocks of the snyder group in. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. Evidence for major mass transfer and volume strain during regional metamorphism of pelites jay j. Metamorphism of the pelitic schists in the bryant pond quadrangle, maine cnanrbs v. Prograde polyphase regional metamorphism of pelitic rocks.
Typical metapelites include wellknown metamorphic rocks such as, for example. Progressive metamorphism of pelitic rocks from the panafrican kaoko belt, nw namibia. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. The results of the previous studies of pelitic siltstone of the ishim formation made it possible to establish that these siliceous deposits are characterized by high dispersion and can be described as a natural silica quartz flour or marshallite a term, which is predominantly used in the countries of the former ussr for pelitic sizegrained quartz smirnov et al. Four aluminosilicatebearing, amphibolite facies pelitic schists sampled from the root of the longlived eastern gondwana continental magmatic arc now exposed in southwest fiordland, new zealand, record remarkably different ptt histories. It occurs in intense tectonic conditions associated with volcanic arcs, and major mountain building. Progressive metamorphism of pelites pelites are among the most important metamorphic rocks for two reasons. An aureole is the zone surrounding an intrusion, which is a mass of igneous rock that solidified between other rocks located within the earth. Thus they are good monitors of regional metamorphic histories.
Mineral assemblages delineate five metamorphic zones within the contact aureole. They are usually poorly foliated and form at intermediate to high grades of metamorphism of basaltic or gabbroic protoliths. A rock at a high metamorphic grade probably progressed through a sequence of mineral assemblages rather than hopping directly from an unmetamorphosed rock to the metamorphic rock. Metamorphism of mafic rocks first evident in the greenschist facies, which correlates with the chlorite and biotite zones of the associated pelitic rocks ftypical minerals include chlorite, albite, actinolite, epidote, quartz, and possibly calcite, biotite, or stilpnomelane fchlorite, actinolite, and epidote impart the. Any type of rockigneous, sedimentary, or metamorphiccan become a metamorphic rock. Metamorphic rocks metamorphic rocks rocks that have been subjected to either enough heat or pressure to cause the minerals in that rock to undergo solid state chemical changes. Petrographic analysis of igneous and metamorphic rocks from the fishguard 1. The mineral assemblages that occur in metamorphic rocks. Hand specimen and thin section description of igneous rocks. Metamorphism of the pelitic rocks of the snyder group in the contact aureole of the kiglapait layered intrusion, labrador. Petrogenesis of metamorphic rocks is, like the preceding six editions, a fine and important book. Progressive metamorphism of pelitic rocks a lab assignment to facilitate translation from afm space to pt space. Each county map has been scaled to fit on lettersize paper.
Test and improve your knowledge of metamorphic rocks with fun multiple choice exams you can take online with. The study uses petrography, wholerock geochemistry and mineral chemistry to identify the. The sulitjelma area of the scandinavian caledonides consists of a variety of metasedimantary units with small basic intrusions, and a large ophiolitic complex of predominantly basic composition. Metapelites, are metamorphic rocks, which derived from contact or regional metamorphism of shale or mudstones clay rich sediments. Winter, chapter 28 metapelite mineralogy fine alkrich phyllosilicates, such as clays montmorillonite, kaolinite, or smectite, fine white micas sericite, paragonite, or phengite and chlorite the phyllosilicates may compose more than 50% of the original sediment fine quartz constitutes another 1030%. Highlevel metamorphism of pelitic rocks in northern new hampshire jouu c. What links here related changes upload file special pages permanent link page. Try and work out whether they are sedimentary, igneous or metamorphic. Why is zircon useful in igneous and metamorphic petrology.
Crustal anatexis and granite petrogenesis during low. Whole rock xrf analyses of 50 rock samples, including all the main lithologies, indicate that leucogranite compositions are uniform and identical to those of migmatite leucosomes. Swallow tail twins 100are commonly observed in the mineral gypsum caso4. The concept was first defined in 1914 by a finnish petrologist, pentti eelis eskola, as any rock of a. The earliest prograde metamorphic changes occurred around 12 kilometers depth while the latest sillimanite faces formed around 35 kilometers depth. The process by which metamorphic rocks are produced is called metamorphism. These can range from textures similar to the original protolith at low grades of metamorphism, to textures that are purely produced during metamorphism and leave the rock with little resemblance to the original protolith. Introducing the rock cycle by creating a 3d model breaking down the earths crust by erosion sedimentary rocks day 9, 10 andor 11 17.