Hf units higher than the probable initial hf isotopic composition of the protolith can be explained by radiogenic 176hf ingrowth from an elevated 176lu177hf phase i. Lawsoniteblueschist facies metamorphic rocks as a reservoir. Felsic rocks and pelitic sediments which are subjected to blueschist facies conditions will form different mineral assemblages than metamorphosed basalt. A facies is a body of rock with specific characteristics. Primary fluids entrapped at blueschist to eclogite. Thickness, from the upper contact to the first appearance of relict sedimentary structure, ranges approximately 1 to 20 feet 0. Fault rocks within the blueschist metabasalts of the diamante. Paleozoic lawsonitebearing lowgrade metabasalts with rare flattened pillow structures occur in the chugoku mountains, southwest japan. Ch 25 metamorphic facies 1 ch 25 metamorphic facies 2. Fe2o3 in the metamorphic evolution of blueschistfacies rocks yielded. Blueschists are formed by low temperature, high pressure blueschist facies regional metamorphism of basaltic protoliths. Blueschistfacies assemblages form at high pressures 800 megapascals, or mpa yet low temperatures republic suggests midcretaceous subduction of the early cretaceous caribbean arc.
Sep 28, 2019 schuster, 1970a which has the facies of a small frullania and agrees with frullania in leaf insertion and branching, has a nontiered seta with 16 epidermal cell rows surrounding 4 inner rows. Ppt ch 25 metamorphic facies powerpoint presentation free. Separate episodes of eclogite and blueschist facies metamorphism. Ductile thrusting recorded by the garnet isograd from. Blueschist metamorphism in an active subduction zone nature.
The phengite has l5 mole% na substituting for k, and the paragonite has 7 mole% k substituting for na. Highpressure greenschist to blueschist facies transition in the maimon formation dominican republic suggests midcretaceous subduction of the early cretaceous caribbean arc. Blueschist is plentiful in the yrekafort jones area, eastern klamath mountains, adjacent to a belt of serpentinite that marks the boundary between two fundamental lithologic units, an eastern belt of early paleozoic sedimentary and metamorphic rocks, and a western greenstonechert assemblage of late paleozoic and triassic. Sassi 5, rolf schmid6 1 institute of geological sciences, polish academy of sciences, warsaw, poland 2 cnrs. Eclogite facies definition of eclogite facies by the. Primary fluids entrapped at blueschist to eclogite transition. High pt sanbagawa or franciscan facies series facies series. Retrograde pumpellyite in the yunotani garnet blueschist of. The metamafic rocks are divided into metapillow basalt core pbc, metapillow basalt rim pbr, and metabasaltic breccia bb. Albiteepidote hornfels facies z likely to be recognized only in the outermost parts of thermal aureoles in country rocks originally of very low metamorphic grade. Eclogite facies conditions of thermodynamic stability of eclogites, defined with respect to the principal factors of metamorphism. The epidote grades contain two varieties, a garnet. The structural evidence and the pressuretemperature paths of the different blocks suggest coupling between blocks and matrix, at least in the blueschist facies. Metamorphic style and development of the blueschist to.
Phase relations in the greenschist blueschist amphiboliteeclogite facies in the system na 2 ocaofeomgoal 2 o 3sio 2h 2 o ncfmash, with application to metamorphic rocks from samos, greece. In contrast, the pbr and bb contain a lawsoniteblueschistfacies mineral assemblage. They also frequently contain lawsonite, epidote, albite, quartz, muscovite, chlorite, andor garnet. Eclogite facies article about eclogite facies by the. The blueschist greenschist facies transition for a model basaltic system na 2 ocaomgoal2o 3sio2h 2 o is defined by a univariant reaction. The pbc have morblike major and trace element concentrations, contain 5 wt% water, and a naamphibole free mineral. High pt metamorphic rocks british geological survey. On the other hand, coals that sharply overlie nonrooted faciesparticularly higher energy sandstone and conglomerate facieswere eroded and transported from a nearby peatforming environment and are genetically related to underlying sediments mccabe, 1984.
Significance of the cana pyroxenelawsonitechlorite. Phengite is predominantly a wellordered 2m, polytype almost free of stacking disorder, except for phengite lamellae intergrown within paragonite. Blueschist, blueschist facies and blueschist facies rocks the name blueschist was established by bailey in 1962. Biology the general aspect or outward appearance, as of a given growth of flora. Read transitional blueschistepidote amphibolite facies metamorphism in the frankenberg massif, germany, and geotectonic implications, journal of metamorphic geology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Halfmicron sized lamellae of phengite were observed intergrown in paragonite, but not vice versa. Ppt ch 25 metamorphic facies powerpoint presentation. In thermally immature rocks, organic facies can be determined by kerogen typing. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from. Reaching the conditions of the epidoteblueschist facies, requires a perturbation of the modeled steadystate pt trajectory, and the essential component is heating at a higher rate figure 2, location 2. A blueschist is a fine to mediumgrained, foliated, metamorphic rock dominated by glaucophane, crossite or riebeckite.
Mineral assemblages from zone i ep free zone of shibakusa 1989 are stable around the following reaction. A low geothermal gradient of around 10 o km would cause prograde metamorphism to occur along a sequence of facies from zeolite to blueschist to eclogite. Pdf the alanya massif, which is located to the south of central taurides in turkey, presents a. Greenschistlike rocks can also be formed under blueschist facies conditions if the original rock contains enough magnesium. The tianshan is the first locality worldwide where primary fluids at blueschist to eclogite transition have been documented. In between, 4 metamorphic zones from high to low grades have been delineated. Conduction is the transfer of heat vibration from one molecule to the adjacent atommolecule dominant form of heat transfer in solids. Blueschist facies metamorphism of peralkaline rhyolites. Types, grade and facies of metamorphism recommendations by the iugs subcommission on th e systematics of metamorphic rocks. Pdf ptt evolution of eclogiteblueschist facies metamorphism in. The blueschistgreenschist facies transition for a model basaltic system na 2 ocaomgoal2o 3sio2h 2 o is defined by a univariant reaction. At that time doubts had arisen whether glaucophane was only stable at elevated pressures or also under greenschist facies conditions. Retrograde pumpellyite in the yunotani garnet blueschist of the omi area, japan.
More recently the term blueschist facies has been preferred because glaucophane is not always developed in many important rock types, for example, graywacke sandstones, which may contain other minerals that are characteristic of high pressure and low. In the late paleozoic blueschist localities in the hidagaien belt and the chugoku moun. Parageneses and compositions of minerals yield equilibrium pt conditions of t free of stacking disorder, except for phengite lamellae intergrown within paragonite. Sugozu nappe, which was affected by the blueschist facies to eclogite. Blueschist facies an overview sciencedirect topics. This file is licensed under the creative commons attributionshare alike 3. A coarsegrained greenish rock consisting primarily of garnet and sodic pyroxene, and often including quartz, kyanite, and rutile. Blueschist facies is determined by the particular temperature and pressure conditions required to metamorphose basalt to form blueschist. According to jones, this technique mainly relies on 1 kerogen identification adequately reflecting petroleum generative potential, 2 kerogen distribution being neither random nor capricious, and 3 the distribution of similar kerogen extending over tens to hundreds of.
Facies definition of facies by the free dictionary. Phase relations in the greenschistblueschistamphiboliteeclogite facies in the system na 2 ocaofeomgoal 2 o 3sio 2h 2 o ncfmash, with application to metamorphic rocks from samos, greece. Pdf eclogite, amphibolite and blueschistfacies rocks from diego. Jadeite andor lawsonite were considered to be more reliable pressure indicators. Subduction and accumulation of lawsonite eclogite and. Convection occurs if the lower part of a fluid body is hotter than the upper part, hot fluid rises away from the heat source bringing heat to the cooler material away from the heat source. Temperaturepressure diagram showing the generally accepted limits of the various facies used in this text. Eclogite fades regional metamorphism of hydrous mafic. This explains the scarcity of blueschist preserved from before the neoproterozoic era ma ago when the earths oceanic crust contained more magnesium than todays oceanic crust. Fedele, l, tramparulo, fda, vitale, s, cappelletti, p, prinzi, ep and mazzoli, s 2018 petrogenesis and deformation history of the lawsonitebearing blueschist facies metabasalts of the diamanteterranova oceanic unit southern italy. Winter 2010 an introduction to igneous and metamorphic petrology. Experimental investigations of blueschistgreenschist. The highpressure veins are predominantly composed of. The blueschist facies has been subdivided into the epidote blueschist facies ebs evans, 1990 or glaucophane greenschist facies and lawsonite blueschist facies lbs dong, 1989, evans, 1990.
Main types of metamorphism regional metamorphism is a type of metamorphism which occu rs over an area of wide extent, that is, affecting a large rock vo lume, and is associated with largescale tectonic processes, such. All the protoliths were subducted, metamorphosed to blueschisteclogite. Indosinian epoch collsional orogenic belt in the lhasa terrane, tibet. It is properly defined on the basis of color, bedding, composition, texture, fossils, and sedimentary structures. The highpressure, lowtemperature metamorphic rocks known as blueschists have long been considered to form in subduction zones, where the descent of a. Fault rocks within the blueschist metabasalts of the. Retrograde pumpellyite in the yunotani garnet blueschist.
Abstract blueschists in the yilan area, heilongjiang province, are known as important parts of the heilongjiang complex. Blueschist accessscience from mcgrawhill education. Jun 23, 2001 the tianshan is the first locality worldwide where primary fluids at blueschist to eclogite transition have been documented. Rock assemblages of eclogite and blueschist in many subduction or suture zones have been reported. Blueschist facies metamorphism and its evolution in the yilan area. Metamorphic facies the concept of metamorphic facies. Phase relations in the greenschistblueschistamphibolite. The time of eclogite facies metamorphism has not been dated radiometrically, but. Epblueschist subfacies, in other words to the uppermost pt conditions of the pmpblueschist subfacies. Schuster, 1970a which has the facies of a small frullania and agrees with frullania in leaf insertion and branching, has a nontiered seta with 16 epidermal cell rows surrounding 4 inner rows. The highpressure, lowtemperature metamorphic rocks known as blueschists have long been considered to form in subduction zones, where the descent of a relatively cold slab leads to the occurrence.
Eclogite facies article about eclogite facies by the free. Ptt evolution of eclogiteblueschist facies metamorphism in. Blueschistfacies metamorphism is important in subduction zones, where. H2o, is an index mineral for highplowt hplt blueschist and eclogitefacies mafic rocks. Eclogite facies metamorphism in sugozu nappe, which consists of homogeneous. Subduction and accumulation of lawsonite eclogite and garnet. Blueschist facies metamorphism of peralkaline rhyolites from. Coexisting paragonitephengite in blueschist eclogite. Blueschistfacies assemblages form at high pressures 800 megapascals, or mpa yet low temperatures blueschist facies. An update on the cooling path yuzuki shinji and tatsuki tsujimori, department of earth science, tohoku university, sendai 9808578, japan center for northeast asian studies, tohoku university, sendai 9808576, japan retrograde pumpellyite was newly found in garnet blueschist that is mgrich. The lbsebs transition has been extensively studied. Nitsch 1968 and liou 1971 independently determined the minimum. Convection occurs if the lower part of a fluid body is hotter than the upper part, hot fluid rises away from the heat source bringing heat to. Winner of the standing ovation award for best powerpoint templates from presentations magazine.
Physical geology, metamorphic rocks, compositional classes, metamorphic grades, metamorphic facies duration. The blueschists, which contain lawsonite and glaucophane or. This is the lowpressure equivalent of the greenschist facies, and the assemblages are very similar. The stability of cana pyroxene in lowgrade metabasites. Blueschist metamorphism in the yrekafort jones area. Reaching the conditions of the epidote blueschist facies, requires a perturbation of the modeled steadystate pt trajectory, and the essential component is heating at a higher rate figure 2, location 2. Highpressure, lowtemperature metamorphism associated with subduction zones which produces a broad mineral association including glaucophane, actinolite. Eclogite facies synonyms, eclogite facies pronunciation, eclogite facies translation, english dictionary definition of eclogite facies. Eclogite facies definition of eclogite facies by the free.
Goldschmidt 1911, 1912a contact metamorphosed pelitic, calcareous, and psammitic hornfelses oslo s. Veins containing highpressure minerals in massive host eclogites transitional to blueschists, or eclogite boudins surrounded by blueschists, indicate that a free fluid phase was present at the time of eclogitization. It is noteworthy that the samples deduced to have come from thicker. Such a progression is termed a facies series, and in general terms this would be called a high pressure facies series, as shown in the diagram below. Maruyama and liou, 1988 rather than prehnitepumpellyitefacies pumpellyite cf. Miyashiro 1961 proposed five facies series simplified to. Eskola proposed a glaucophaneschist facies of regional metamorphism. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect. The blue color of the rock comes from the presence of the predominant minerals glaucophane.
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