These keywords were added by machine and not by the authors. Evidence for major mass transfer and volume strain during. The fate of graphite in prograde metamorphism of pelites. It represents a common type of regional pelitic orogenic metamorphism. Typical granulite facies mineral assemblages and reaction textures suggest that these rocks experienced hp granulite facies metamorphism and overprinted decompression along a clockwise pt loop. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn.
Review naming metamorphic rocks what is the difference. The metamorphic rocks of the southern part of the mainland. Results from integrated upb dating and ree analysis. Pdf progressive metamorphism of pelitic rocks from greenschist to. Quartz and feldspar are the dominant phases, rather than the phyllosilicates, and calciumbearing phases are common. Pdf progressive metamorphism of pelitic rocks from. Barrovian metamorphism is the most commonly encountered. Metamorphic rock metamorphic rock pressuretemperaturetime paths. It occurs in intense tectonic conditions associated with volcanic arcs, and major mountain building. 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.
Very lowgrade metamorphic evolution of pelitic rocks under high. Quantifying the tectonometamorphic evolution of pelitic. Petrogenesis of metamorphic rocks kurt bucher springer. A process of change 1 metamorphic rock forms from a preexisting rock or protolith. Quantifying the tectonometamorphic evolution of pelitic rocks from a. Metamorphic petrology 3 metamorphism of pelitic rocks minerals and isograds. The diagrams help to determine the pressure and temperature conditions under which a given set of metamorphic rocks. 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. Interaction between metamorphism and deformation part 12. Decompressional coronas around garnet grains can be observed in all these pelitic rocks. Pdf prograde polyphase regional metamorphism of pelitic rocks. Winter 2010 an introduction to igneous and metamorphic petrology. The term was earlier used by geologists to describe a clayrich, finegrained clastic sediment or sedimentary rock, i. Mineralogical, mineral chemical, and whole rock chemical data for the sulfiderich schists indicate th.
Metamorphic petrology 1 metamorphic processes, contact, regional, t and p variations. 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. Lecture eight metamorphism of pelitic rocks metapelites 1 lecture eight metamorphism of pelitic rocks metapelites part i 2 what is the metapelites. Metamorphism is a subsolidus process leading to changes in mineralogy andor texture for example grain size and often in chemical composition in a rock. The pelitic rocks in the bryant pond area have been metamorphosed to the sillimanite and sillimanitepotash feldspar grades of metamorphism and an isograd fig. Barrovian metamorphism in the southern appalachian orogen. Evidence for major mass transfer and volume strain during regional metamorphism of pelites jay j. Regional thermal metamorphism and deformation of the sitka. Figure 6 shows metamorphic rock names in relation to protolith and grade of metamorphism. Petrology of graphitic sulfiderich schists from south. Pdf prograde polyphase regional metamorphism of pelitic. 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. 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. In the study of very low and lowgrade metamorphic rocks, maturation of organic matter and.
Yet, high grade metamorphic rocks are common at the surface of the earth and usually show only minor retrograde minerals. Tectonic evolution of lower crustal rocks in an exposed. This process is experimental and the keywords may be updated as the learning algorithm improves. A regional study of metamorphosed pelitic rocks in. The chemical components and crystal structures of the minerals making up the rock may change even. Symmes gh, ferry jm 1992 the effect of whole rock mno content on the stability of garnet in pelitic schists during metamorphism. This area is characterised by a thick sequence of medium to high grade metamorphic rocks such as biotitechlorite schists, garnetmica schist. Introductory phase equilibria and thermodynamics part 5. Metamorphism of mafic, calcareous and ultramafic rocks.
Moreover, compositions of coexisting minerals show regular variation with imposed. Progressive metamorphism of pelitic and quartzofeldspathic. Petrogenesis of metamorphic rocks presents a large number of diagrams showing the stability relations among minerals and groups of minerals found in metamorphic rocks. Lowgrade metamorphism of paleozoic formations of the szendro mountains nehungary. Metamorphism of mafic, calcareous and ultramafic rocks content writer. Metapelites, are metamorphic rocks, which derived from contact or regional metamorphism of shale or mudstones clay rich sediments. Partial melting white mica amphibolite facies contact aureole pelitic rock. Many distinct metamorphic minerals are found in metapelitic rocks e. A similar group of metamorphic rocks occurs to the north of the great glenn fault a strikeslip fault and is called. 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. Observed mineral assemblages in the pelitic metamorphic rocks of southern. Appendix b classification of metamorphic and other compositegenesis rocks, including hydrothermally altered, impactmetamorphic, mylonitic, and cataclastic rocks, version 1. Thermal metamorphism thermal metamorphism occurs where granite is in intrusive contact with country rocks. Prograde polyphase regional metamorphism of pelitic rocks, nw of jamshedpur.
Metamorphic petrology 2 metamorphic facies heat flow and heat production in crust. In a later metamorphism a belt of these rocks a kilometer or so wide became gneissified, probably due to the passage of high temperature fluids. Contrib mineral petrol amphibolite facies contact aureole pelitic rock prograde metamorphism. Prograde polyphase regional metamorphism of pelitic rocks, nw of jamshedpur, eastern india.
Rock metamorphism is a geological process that changes the mineralogical and chemical composition, as well as the structure of rocks. Metamorphism of the pelitic rocks of the snyder group in the contact aureole of the kiglapait layered intrusion, labrador. The approximate location of the pelitic zones of barrovian metamorphism are included for comparison. Prograde polyphase regional metamorphism of pelitic rocks. Metamorphism of the pelitic rocks of the snyder group in. Metamorphic petrologists studying contact metamorphism early in the 20th century introduced the idea of metamorphic facies part of a rock or group of rocks that differs from the whole formation to correlate metamorphic events. If the inline pdf is not rendering correctly, you can download the pdf file here.
The concept was first defined in 1914 by a finnish petrologist, pentti eelis eskola, as any rock of a. These changes are due to physical andor chemical conditions that differ from those normally occurring at the surface of planets and in zones of cementation and diagenesis below this surface. Eoalpine cretaceous very low to lowgrade metamorphism. The pt gradient in a late eocene lowt highp metamorphic belt in northern new caledonia increases from sw to ne. 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. For simplistic reasons we will focus here in the introduction dominantly on changes in p and t. Barrovian metamorphism is widely found across time and space on all parts of the earth, and produces the most common metamorphic rocks.
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. P t and p m h 2 o pseudosections are used here to establish the phase relationships of the pelitic felsic rocks in south tianshan. 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. A more precise location is presented on a geologic map by guidotti 1963. Metamorphic rock metamorphic rock metamorphic facies. Metamorphism of the pelitic schists in the bryant pond quadrangle, maine cnanrbs v. As a result of this metamorphism the pelitic rocks over the whole area became schists containing such minerals as biotite, chlorite, muscovite, quartz and feldspar, and possibly garnet. Progressive metamorphism of pelitic rocks a lab assignment to facilitate translation from afm space to pt space. 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. 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. 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%. Pelitic rocks are slates or phyllites and typically. Metamorphism of pelitic rocks metapelites springerlink.
All chapters of part ii of the book have been rewritten. Metamorphism of highultrahighpressure peliticfelsic. Also, the chapters introduction and grade have undergone several major changes. Metamorphism is typically associated with elevated temperature and pressure, thus it affects rocks within the earths crust and mantle. 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. 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. Quantifying the tectonometamorphic evolution of pelitic rocks from a wide range of tectonic settings. Typical mineral changes that take place in metabasic rocks during progressive metamorphism in the medium pt facies series. Additional minerals that may occur include stilbite, calcite, stilpnomelane, actinolite and hornblende. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. The mineral assemblages that occur in metamorphic rocks. At the peak, incipient partial melting of pelitic and psammitic gneisses took place in the amphibolitegranulite facies transition zone, the melt and residuals cutting the foliations formed by flattening.
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 describes the changes a rock undergoes with changing p, t and composition x. The major types of sedimentary rocks distribution of sediments on the earths surface. The quartzofelspathic rocks differ from the pelitic rocks. Petrology of a medirrmpressure regional metamorphic terrane. The progressive nature of metamorphism 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. Pdf the study area belongs to the singhbhum metamorphic belt of jharkhand, situated in the eastern part of india. The study group was also asked to consider metamorphism associated with other localised heat sources, such as combustion metamorphism and ligthning strikes. He observed that as a pelitic rock undergoes higher pressures and temperatures, its mineral assemblage changes from predominantly chlorite to biotite to garnet to staurolite to kyanite to sillimanite.
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