These series of metamorphic facies are presented in the PT-diagram of meta­ morphic facies (Fig. Prentice Hall. Lines A, B, and C show the geothermal gradients that would be encountered at the three marked positions on the diagram of a subduction zone above. The upper red line is the prograde path, the lower the retrograde. 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. Eclogite (Facies) Metamorphic facies in which mafic rocks have sodic pyroxene and almandine-pyrope garnet. 1 Metamorphic Reactions and Stable Assemblages GEOL 13.53 Metamorphic Lecture 3 Eskolaand Metamorphic Facies • Eskola(1914, 1915) noted that metapeliticrocks in southern Finland (Orijärvi) contained the assemblage Bt-Ms whereas near Oslo, rocks contained the compositionally equivalent mineral assemblage Kf-Cd • If rocks are the same composition, then the mineralogical difference must … A more complete indication of this intensity or degree is provided with the concept of metamorphic facies.. Since pressure relates to depth of burial. A p-t-diagram is designed, utilizing the latest equilibrium determinations at high pressures and temperatures on rockforming silicates. A three-component phase diagram used for metamafic rocks. [photo: A L … ACF diagram A three-component, triangular graph used to show how metamorphic mineral assemblages vary as a function of rock composition within one metamorphic facies.Besides SiO 2, the five most abundant oxides found in metamorphic rocks are Al 2 O 3, CaO, FeO, MgO, and K 2 O. Metamorphic Petroogy - Geology Metamorphic Petrology with Rebecca Jamieson at Dalhousie University - StudyBlue Flashcards The PT diagram in Figure 8.69 shows the most important of these series. These are also called metamorphic facies series.A metamorphic facies series is a sequence of metamorphic facies which plot in a temperature-pressure diagram along a line, and this line represents a certain geothermal gradient. The diagram at right shows the distribution of metamorphic facies with temperature and pressure. Blueschist (Facies) The metamorphic facies in which mafic rocks have glaucophane and sodic pyroxene. I’ve taken a standard diagram of metamorphic facies and drawn on roughly some typical P-T-t paths. The computer program Theriak-Domino provided pseudo sections (PT diagram) with possible PT stability fields illustrated by the microstructure and mineral analysis. Assumptions involved in defining the concept of metamorphic facies. Kbars-1Kbar=100MPa. K. Bucher, in Encyclopedia of Geology, 2005. Metamorphic zones, isograde and reaction isograde, Concept of classification of metamorphic facies, facies-series and grade, structure and textures of metamorphic rocks; chemographic projection, graphical representation of metamorphic minerals assemblages; ACF, AKF, AFM and others diagram. What might pressure be measured in on a PT diagram instead of GPa? Introduction to chemographic analysis; Gibbs Phase Rule; properties of triangular diagrams; ACF diagram. The three components plotted on ACF diagrams are A(Al 2 O 3), C(CaO), and F(FeO + MgO), making the … Metamorphic zones, isograde and reaction isograde, Concept of classification of metamorphic facies, facies-series and grade, structure and textures of metamorphic rocks; chemographic projection, graphical representation of metamorphic minerals assemblages; ACF, AKF, AFM and others diagram. What is a P-T-t path? Franciscan Facies Series (high-P, low T) 11 Fig. Concept of metamorphic facies. Temperaturepressure diagram showing the three major types of metamorphic facies series proposed by Miyashiro (1973, 1994). Different rocks reach different peak temperatures, varying from lower grade greenschist rocks up to granulite facies gneisses. Examples of nine common types are given. The passage of this water through the oceanic crust at 200° to 300°C promotes metamorphic reactions that change the original pyroxene in the rock to chlorite and serpentine. Yellow star denotes the location in PT space of Why is approximate depth shown on a PT diagram? 1.-Tentative PT diagram showing possible stability fields of metamorphic facies and PT gradients curve of the granite (Tuttle and Bowen, 1958), to the curve for low-high quartz (Yoder, 1950), and to the lo 1964). place letters in the white circles that are linked to the starred locations on this illustration to show where Eskola's facies are most likely to occur A - amphibolite, G = greenschist Eeclogie, B = blueschist. As a model for progressive metamorphism, petrologists consider different metamorphic facies series, the sequences of metamorphic rocks that would form in different metamorphic environments. 2). Other rocks of contrasting … ACF Diagram. P-T-t Paths . blueschist to eclogite facies metamorphism). Metamorphic grade is an informal indication of the amount or degree of metamorphism. Facies metamorphic rocks and their relative positions in space PT. ... What is the intercept on a PT diagram considered to be? high. This diagram is in good agreement with previous published facies diagram (e.g. There are forty years of manufacturing history, with three major production bases,over 160 senior R&D engineers and 600+ large and medium-sized digital processing equipment, The first-line technicians and professional after-sales service personnel up to 2,300+ and 200+ respectively.Introducing advanced technology and craftsmanship, adopting international … This diagram has been used for figures 6 and 7. Western Norway. What is a metamorphic facies? METAMORPHIC FACIES In general, metamorphic rocks do not drastically change chemical composition during metamorphism, except in the special case where metasomatism is involved. Note that any two of these minerals can occur together only under 12 40 PT conditions represented by the boundary lines in the diagram and that the three minerals Figure A7.5.2 can occur together only at the point where these three lines intersect: approximately 500'C and 4 kilobars, which normally occurs about 15 km below Earth's surface 1. Donna Whitney, University of Minnesota . Blueschist Eclogite Granulite Amphibolite t Zeolite Pyroxene Hornfels Hornblende Hornfels Sanadinite Act-Ep Hornfels Prehnite-Pumpellyite 15 10 5 0 200 400 600 800 The pressure (P) - temperature (T) - time (t) path of a metamorphic rock is the set of all P-T conditions experienced by a rock during its metamorphic history (Figure 1). 25.3. The metamorphic facies scheme (Figures 1 and 2) requires the presence of a free aqueous fluid.The facies figures have been prepared with this premise. (4 pt) Metamorphic Facies (Tray 5) One of the primary goals of metamorphic petrology is to interpret the pressure (P) and temperature (T) history of a rock or set of rocks, because it provides information about the tectonic history of a region. 12 Metamorphic Facies Figure 25.4. Mafic Rocks Read Chapter 4 of An Introduction to Metamorphic Petrology by Bruce Yardley or Chapter 25 of Igneous and Metamorphic Petrology by John Winter or Chapter 16 of Igneous and Metamorphic Petrology by Philpotts. Daly) Metabasite mineral assemblages; Classification of metamorphic grade based on metabasite assemblages; facies in PT space. One of the first uses of these types of diagrams was by Eskola (1915) who employed a diagram known as the ACF diagram in his study of metamorphic rocks. zeolite facies A set of metamorphic mineral assemblages produced by the metamorphism of a wide range of starting rock types under the same metamorphic conditions, and typically characterized by the development of the mineral assemblage smectite—zeolites (in addition to relict igneous plagioclase and pyroxene) in rocks of basic igneous composition. It represents high P/T metamorphism. Above, some exceptions from this requirement have been given with respect to the granulite and sub-greenschist facies. Lecture 5: Metabasites and facies (Prof. J.S. Surface conditions. 6 Norway, Western Gneiss Complex Eclogite facies, partly retrogressed. Winter (2010) An Introduction to Igneous and Metamorphic Petrology. Figure 1: Pressure-temperature diagram illustrating metamorphic facies boundaries. These seem to occur at different pressure levels and are distinguished by different series of mineral assemblages. Yardley, 1989; Spear, 1993; Bousquet et … Dashed red arrow indicates the typical PT path that subducted packages of rock follow in a long-lived subduction zone (i.e. contact metamorphism iron ore. Finnish geologist Pentii Eskola devised a facies scheme in 1915 (that Metamorphism is a dynamic process, involving changes in temperature ± pressure through time. Metamorphic facies. Figure 3: Metamorphic facies diagram for metapelites and metabasites (modified after Oberhänsli et al. Partial Melting and Igneous Processes. The changes in mineral assemblages are due to changes in the temperature and pressure conditions of … Margin of metabasic eclogite body against amphibolite-facies gneiss. However, most minerals are solid solutions that undergo compositional … Metamorphic rock - Metamorphic rock - Pressure-temperature-time paths: 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 steady-state geotherms. See diagram for more detail. George Barrow was a geologist in Scotland who discovered the Barrovian series.. Solid solutions, chemical reactions and metamorphic facies. Part 6. Metamorphic facies found in the Grenville province of Ontario collectively define a PT trend that is transcursive to the PT trends of Miyashiro's faci… Solid Solutions and Exchange Vectors Some minerals (e.g., quartz) have constant composition. 8.6.2.2 Facies Series 8.69 Metamorphic facies series. Study 101 Metamorphic Petroogy flashcards on StudyBlue. In the black diagram of a subduction zone (Fig. Stability boundaries of the other index minerals are … Fresh eclogite on the right grades into darker-coloured rock in which omphacite is replaced by diopside-plagioclase-amphibole intergrowths. A7.5.5. Metabasite mineral assemblages in the ACF diagram. Position on the conditions of pressure and temperature of each type of PT diagram a metamorphic. evaluation of metamorphic conditions, as well as determination of the PT conditions with the use of the computer program Theriak-Domino. In order to point out some useful aspects of the facies series in various types of metamorphism, the possible stability fields of the facies described from areas of progressive metamorphism are shown in a hypothetical PT diagram. 2004). Metamorphic grades. Metamorphic series include the Barrovian and Buchan series of metamorphic rocks. For abbreviations see Table 2. FIG. Sanbagawa Facies Series (high-P, moderate-T) 5. Because this metamorphism takes place at temperatures well below the temperature at which the rock originally formed (~1200°C), it is known as retrograde metamorphism .

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