DOCSLIB.ORG

The Greenschist-Amphibolite Transition in the CFM Projection

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Greenschist-Amphibolite Transition in the CFM Projection American Mineralogist, Volume 69, pages 250-251, 1984 The greenschist-amphibolitetransition in the CFM projection Rtcua,Ro N. Annorr, Jn. Department of Geology Appalachian State University, Boone, North Carolina 28608 Abstract The CFM projection(C = CaO+Na2O+K2O-AlzOr, F : FeO-FezO:, M = MgO) was originally designedfor illustrating mineral assemblagesin upper amphibolite and granulite facies quartz-feldspar-magnetite-bearingmetabasites. By introducing chlorite, the projec- tion can also be used to illustrate mineral assemblagesin greenschistfacies quartz- feldspar-magnetite-bearing metabasites. The greenschist-amphibolite facies transition takes place in the context of Abbott's (1982)lowest gradeCFM topology. In metabasites,the change from the greenschistfacies by the addition of chlorite. Actinolites and hornblendes to the amphibolite facies commonly proceeds with no plot in the same part of the CFM diagram and since the changein the mineralassemblage other than (l) a change changefrom the former to the latter is, in many instances, in the compositionsof the mineralsand (2)a changein the continuous, this change has virtually no visible affect on modalproportions of the minerals(Laird, 1980;Thomp- the CFM topologies.Also, becauseplagioclase does not son et al., 1982;Laird in Robinson et al., 1982).The appear in the CFM projection, the changefrom albite to common assemblageis amphibole (Amp) + chlorite (Chl) oligoclase has no visible affect on the CFM topologies. + plagioclase(Pla) + epidote(Epi) + quartz (Qtz)+Fe3+ The purpose of this note is to show that by introducing oxide (hematite or magnetite : MCt)tTi-mineral (ilmen- chlorite in the CFM projection the petrogenetic grid, ite or sphene)-+K-mica(muscovite of biotite = Bio)tcar- which I originally designedfor amphibolite and granulite bonate (calcite or ankerite)rgarnet (Gar). In the green- facies rocks, applies just as well to lower grades where schist facies, the amphiboleis actinolite (Act) and the typical greenschistassemblages are possible. plagioclaseis albite. In the amphibolite facies, the amphi- By several indications(Winkler, 1979;Turner, 1968; bole is hornblende(Hnb) and the plagioclaseis oligoclase Dobretsovet al., 1972)Chl+Epi+Qtz+Mgt+albite is an or a more calcic plagioclase. The whole-rock reaction important greenschist assemblageat temperatures well relating the two facies is polyvariant and has been treated above the first appearanceofamphibole, biotite or garnet recently in an elegant fashion by Thompson et al. (1982) in rocks of higherFeO/MgO. In most greenschists,these and by Laird in Robinsonet al. (1982).In theseworks, minerals appearas the result of divariant CFM reactions. the changesfrom actinolite to hornblendeand from albite The usual order of appearancewith increasing grade of to oligoclasewere modelled as continuous reactions. metamorphism is actinolite, biotite, garnet (Winkler, Abbott (1982)presented a petrogeneticgrid for amphib- 1979;Turner, 1968;Dobretsov et al., 1972).However, olite and granulite facies metabasites, based on phase garnet may appear at a lower grade than the biotite if the relationshipsin the CFM projection (Q : CaO+Na2O K2O contentof the rock is very low, in which casebiotite +K2O-Al2Or, F: FeO-Fe2O3,M = MgO). The CFM may not appear at all. Normally the K2O content is high projection is useful for illustrating mineral assemblagesin enoughto sustainbiotite (or someother K-bearingminer- metabasitescontaining qvar1"z,magnetite and one or two al, Laird, 1980).For the purposesofthis note, thereis no feldspars. The grid consists of 26 P-T regions, each need to consider CFM topologies without amphibole, characterizedby a distinct CFM topology. Boundaries biotite and garnet. between the P-T regions are mineral reactions involving The most likely CFM topology for the greenschist combinations of four of the CFM minerals hornblende, facies is shown in Figure la. The topology is derived from biotite, garnet, epidote, clinopyroxene, orthopyroxene Abbott's (1982)CFM topology l, 5 or 6 by the additionof and fayalite. Quartz, feldspar and magnetiteare involved chlorite. All of the three-phase CFM assemblagesin as neededfor balancing the reactions. Figure la are naturally occurring (Abbott, 1982;for the Some of the lowest grade CFM topologies(e.g., P-T chlorite-bearingassemblages, Winkler, 1979; Turner, regions1,5, and 6 in Figure 3 of Abbott, 1982)would be 1968;Dobretsov et al.,1972;Spear,1982).The partition- consistentwith the greenschistfacies if (l) the amphibole ing of FeO and MgO, Xr"o : FeO/(MgO+FeO),between were actinolite instead of hornblende, (2) the plagioclase chlorite and other minerals in metabasitesis Xp"6 (Chl) > were albite and (3) if the CFM topologies were modified Xr"o (Act), XF"o (Chl) = Xn.o (Hnb), XF"o (ChD l Xr.o 0003-004xE4/03M-0250$02.00 250 ABBOTT: GREENSC HI ST-AM PHIB OLITE TRANSITIO N 25r Epi is Chl+Epi, Chl+Epi+Amp, Chl+Amp, Chl+Amp+ Bio, Bio+Amp, Bio*Amp+Epi. The chlorite-bearing * Quortz assemblagesare typical of the greenschistfacies where +Plogioclose the amphibole is actinolite and the plagioclaseis albite. +M ognetite The assemblageswithout chlorite are typical of the am- t K-teldspor phibolite facies where the amphibole is hornblende and the plagioclaseis oligoclase.Very commonly metabasites (metabasalts)are in the Amp+Epi+Chl field when the greenschist-amphibolitetransition takes place (Thomp- A sonet al., 1982;Laird rn Robinsone t al., 1982).For bulk / / compositions higher in FeO/MgO, the greenschist-am- Bio \ \ phibolite transition may occur in one of the chlorite- absent assemblages.For compositions lower in Gor Chl Gor Chl FeO/MgO, the facies transition may occur in the amphi- bole-absentassemblage Chl+ Epi. Topology 1,5or 6 I suggestthe greenschist-amphibolitetransition takes Low T Low K2O place in Abbott's (1982)lowest grade CFM topology. If the K2O content of the rock is very low, biotite may not o. b. be possible. Under these circumstances,the greenschist- amphibolite transition probably takes place in the context Fig. 1. CFM projectionsfor greenschist grade and low of the CFM topology shown in Figure lb. amphibolitemetabasites. C = CaO+Na2O+K2O-AI2O3,F = = FeO-Fe2O3,M MgO. In eachprojection X marksa bulk Acknowledgments compositionexpressed by the mineralassemblage Chl+Epi. Amp= s-06;6ole,Bio : biotite,Chl = chlorite,Epi = epidote, I wish to thank Jo Laird, Harry Y. McSween,Loren A. 641 : garnet.a. Portionof the CFM projectionfor Abbott's Raymond,J. G. Liou, DavidA. Hewitt andJohn P. Hoganfor (1982)P-T reeionsl, 5 or 6 modifiedby the additionof chlorite. their helpfulcomments. b. HypotheticalCFM projectionfor low K2O. References Abbott, R. N., Jr. (1982)A petrogeneticgrid for high grade (Gar) and XF"o (Chl) ( Xr"o (Bio) (Laird, 1980). The metabasites.American Mineralogist, 67, 865-876. epidotein Figure I is Ca2Fe3+AlzSi:Orz(OH);more alu- Dobretsov,N. L., Khlestov,V. V. andSobolev, V. S. (1972) minousepidotes plot closerto C. TheFacies of RegionalMetamorphism at ModeratePressures. As the temperatureincreases, Xp"6 decreasesfor Gar, (Transl.D. A. Brown, AustralianNational University, Can- Bio and Chl in the various three-phaseCFM regionsin berra.1973). (1980) Figure la. Where the amphibole is actinolite, Xr"o (Act) Laird, J. Phaseequilibria in maficschist from Vermont. Joumalof Petrology,2l, l-37. for the three-phaseCFM region Act+Chl+Epi may in- Robinson,P., Spear,F. S., Schumaker,J. C., Laird,J., Klein, creaseslightly with increasingtemperature (Laird, 1980; C., Evans,B. W. andDoolan, B. L. (1982)Phase relations of Laird in Robinson et al., 1982).The three-phaseregion metamorphicamphiboles: Natural occurrence and theory.In expands with increasing temperature, such that the D. R. Veblenand P. H. Ribbe,Eds., Amphiboles: Petrology Act+Epi join rotates slightly to higher Xp"e and the and ExperimentalPhase Relations, p. l-227. Mineralogical Chl+Epi join rotatesto lowerXp"e. Wherethe amphibole Societyof America,Reviews in Mineralogy,Volume 98. in Figure la is hornblende, Xp"q (Hnb) decreases or Spear,F. S.(1981) An experimentalstudy ofhornblende stability remainsconstant with increasinggrade (Spear, l98l), and and compositionalvariability in amphibolite.American Jour- all three-phaseregions move to the right (to lower Xp"e) nalof Science.281.697J34. (19E2) with increasing temperature. With regard to the model Spear,F. S. Phaseequilibria ofamphibolites from thePost PondVolcanics, Mt. Cube Vermont.Journal of assemblage,Amp+Chl+Epi+Pla, of Thompson er a/. Quadrangle, Petrology,23,383426. (1982),this changein the projection CFM is accommodat- Thompson,J. 8., Jr., Laird, J. and Thompson,A. B. (19E2) ed principally by the reaction: Reactionsin amphibolite,greenschist and blueschist, Journal Epi + Chl: Amp ofPetrology,23,1-27. Turner,F. J. (1968)Metamorphic Petrology. McGraw-Hill, New Quartz, feldspar, Fe3+ oxide and H2O are involved as York. neededfor balancing the reaction. A metabasite,initially Winkler,H. G. F. (1979)Petrogenesis of MetamorphicRocks. in the Chl+Epi field, but wirh C(C+F+M) slightly less 5th Edition.Springer Verlag, New York. than Amp (X in Figure la and b) will be situated in different fields as the temperature increases. In order from low to high temperature,for Abbott's (1982)CFM Manuscriptreceived, December 21, 1982; topologiesI , 5 or 6 (Fig. la), the sequenceof assemblages acceptedforpublication, August 24, 1963..
Load more

Recommended publications
  • The Diversity of Magmatism at a Convergent Plate
    1 Flow of partially molten crust controlling construction, growth and collapse of the Variscan orogenic belt: 2 the geologic record of the French Massif Central 3 4 Vanderhaeghe Olivier1, Laurent Oscar1,2, Gardien Véronique3, Moyen Jean-François4, Gébelin Aude5, Chelle- 5 Michou Cyril2, Couzinié Simon4,6, Villaros Arnaud7,8, Bellanger Mathieu9. 6 1. GET, UPS, CNRS, IRD, 14 avenue E. Belin, F-31400 Toulouse, France 7 2. ETH Zürich, Institute for Geochemistry and Petrology, Clausiusstrasse 25, CH-8038 Zürich, Switzerland 8 3. Université Lyon 1, ENS de Lyon, CNRS, UMR 5276 LGL-TPE, F-69622, Villeurbanne, France 9 4. Université de Lyon, Laboratoire Magmas et Volcans, UJM-UCA-CNRS-IRD, 23 rue Dr. Paul Michelon, 10 42023 Saint Etienne 11 5. School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth,UK 12 6. CRPG, Université de Lorraine, CNRS, UMR7358, 15 rue Notre Dame des Pauvres, F-54501 13 Vandoeuvre-lès-Nancy, France 14 7. Univ d’Orléans, ISTO, UMR 7327, 45071, Orléans, France ; CNRS, ISTO, UMR 7327, 45071 Orléans, 15 France ; BRGM, ISTO, UMR 7327, BP 36009, 45060 Orléans, France 16 8. University of Stellenbosch, Department of Earth Sciences, 7602 Matieland, South Africa 17 9. TLS Geothermics, 91 chemin de Gabardie 31200 Toulouse. 18 19 [email protected] 20 +33(0)5 61 33 47 34 21 22 Key words: 23 Variscan belt; French Massif Central; Flow of partially molten crust; Orogenic magmatism; Orogenic plateau; 24 Gravitational collapse. 25 26 Abstract 27 We present here a tectonic-geodynamic model for the generation and flow of partially molten rocks and for 28 magmatism during the Variscan orogenic evolution from the Silurian to the late Carboniferous based on a synthesis 29 of geological data from the French Massif Central.
    [Show full text]
  • Facies and Mafic
    Metamorphic Facies and Metamorphosed Mafic Rocks l V.M. Goldschmidt (1911, 1912a), contact Metamorphic Facies and metamorphosed pelitic, calcareous, and Metamorphosed Mafic Rocks psammitic hornfelses in the Oslo region l Relatively simple mineral assemblages Reading: Winter Chapter 25. (< 6 major minerals) in the inner zones of the aureoles around granitoid intrusives l Equilibrium mineral assemblage related to Xbulk Metamorphic Facies Metamorphic Facies l Pentii Eskola (1914, 1915) Orijärvi, S. l Certain mineral pairs (e.g. anorthite + hypersthene) Finland were consistently present in rocks of appropriate l Rocks with K-feldspar + cordierite at Oslo composition, whereas the compositionally contained the compositionally equivalent pair equivalent pair (diopside + andalusite) was not biotite + muscovite at Orijärvi l If two alternative assemblages are X-equivalent, l Eskola: difference must reflect differing we must be able to relate them by a reaction physical conditions l In this case the reaction is simple: l Finnish rocks (more hydrous and lower MgSiO3 + CaAl2Si2O8 = CaMgSi2O6 + Al2SiO5 volume assemblage) equilibrated at lower En An Di Als temperatures and higher pressures than the Norwegian ones Metamorphic Facies Metamorphic Facies Oslo: Ksp + Cord l Eskola (1915) developed the concept of Orijärvi: Bi + Mu metamorphic facies: Reaction: “In any rock or metamorphic formation which has 2 KMg3AlSi 3O10(OH)2 + 6 KAl2AlSi 3O10(OH)2 + 15 SiO2 arrived at a chemical equilibrium through Bt Ms Qtz metamorphism at constant temperature and =
    [Show full text]
  • Finding of Prehnite-Pumpellyite Facies Metabasites from the Kurosegawa Belt in Yatsushiro Area, Kyushu, Japan
    Journal ofPrehnite Mineralogical-pumpellyite and Petrological facies metabasites Sciences, in Yatsushiro Volume 107, area, page Kyushu 99─ 104, 2012 99 LETTER Finding of prehnite-pumpellyite facies metabasites from the Kurosegawa belt in Yatsushiro area, Kyushu, Japan * * ** Kenichiro KAMIMURA , Takao HIRAJIMA and Yoshiyuki FUJIMOTO *Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kitashirakawa Oiwakecho, Kyoto 606-8502, Japan ** Nittetsu-Kogyo Co., Ltd, 2-3-2 Marunouchi, Chiyoda, Tokyo 100-8377, Japan. Common occurrence of prehnite and pumpellyite is newly identified from metabasites of Tobiishi sub-unit in the Kurosegawa belt, Yatsushiro area, Kyushu, where Ueta (1961) had mapped as a greenschist facies area. Prehnite and pumpellyite are closely associated with chlorite, calcite and quartz, and they mainly occur in white colored veins or in amygdules in metabasites of the relevant area, but actinolite and epidote are rare in them. Pumpellyite is characterized by iron-rich composition (7.2-20.0 wt% as total iron as FeO) and its range almost overlaps with those in prehnite-pumpellyite facies metabasites of Ishizuka (1991). These facts suggest that the metabasites of the Tobiishi sub-unit suffered the prehnite-pumpellyite facies metamorphism, instead of the greenschist facies. Keywords: Prehnite-pumpellyite facies, Lawsonite-blueschist facies, Kurosegawa belt INTRODUCTION 1961; Kato et al., 1984; Maruyama et al., 1984; Tsujimori and Itaya, 1999; Tomiyoshi and Takasu, 2009). Until now, The subduction zone has an essential role for the global there is neither clear geological nor petrological evidence circulation of solid, fluid and volatile materials between suggesting what type of metamorphic rocks occupied the the surface and inside of the Earth at present.
    [Show full text]
  • The Origin of Formation of the Amphibolite- Granulite Transition
    The Origin of Formation of the Amphibolite- Granulite Transition Facies by Gregory o. Carpenter Advisor: Dr. M. Barton May 28, 1987 Table of Contents Page ABSTRACT . 1 QUESTION OF THE TRANSITION FACIES ORIGIN • . 2 DEFINING THE FACIES INVOLVED • • • • • • • • • • 3 Amphibolite Facies • • • • • • • • • • 3 Granulite Facies • • • • • • • • • • • 5 Amphibolite-Granulite Transition Facies 6 CONDITIONS OF FORMATION FOR THE FACIES INVOLVED • • • • • • • • • • • • • • • • • 8 Amphibolite Facies • • • • • • • • 9 Granulite Facies • • • • • • • • • •• 11 Amphibolite-Granulite Transition Facies •• 13 ACTIVITIES OF C02 AND H20 . • • • • • • 1 7 HYPOTHESES OF FORMATION • • • • • • • • •• 19 Deep Crust Model • • • • • • • • • 20 Orogeny Model • • • • • • • • • • • • • 20 The Earth • • • • • • • • • • • • 20 Plate Tectonics ••••••••••• 21 Orogenic Events ••••••••• 22 Continent-Continent Collision •••• 22 Continent-Ocean Collision • • • • 24 CONCLUSION • . • 24 BIBLIOGRAPHY • • . • • • • 26 List of Illustrations Figure 1. Precambrian shields, platform sediments and Phanerozoic fold mountain belts 2. Metamorphic facies placement 3. Temperature and pressure conditions for metamorphic facies 4. Temperature and pressure conditions for metamorphic facies 5. Transformation processes with depth 6. Temperature versus depth of a descending continental plate 7. Cross-section of the earth 8. Cross-section of the earth 9. Collision zones 10. Convection currents Table 1. Metamorphic facies ABSTRACT The origin of formation of the amphibolite­ granulite transition
    [Show full text]
  • Oregon Geologic Digital Compilation Rules for Lithology Merge Information Entry
    State of Oregon Department of Geology and Mineral Industries Vicki S. McConnell, State Geologist OREGON GEOLOGIC DIGITAL COMPILATION RULES FOR LITHOLOGY MERGE INFORMATION ENTRY G E O L O G Y F A N O D T N M I E N M E T R R A A L P I E N D D U N S O T G R E I R E S O 1937 2006 Revisions: Feburary 2, 2005 January 1, 2006 NOTICE The Oregon Department of Geology and Mineral Industries is publishing this paper because the infor- mation furthers the mission of the Department. To facilitate timely distribution of the information, this report is published as received from the authors and has not been edited to our usual standards. Oregon Department of Geology and Mineral Industries Oregon Geologic Digital Compilation Published in conformance with ORS 516.030 For copies of this publication or other information about Oregon’s geology and natural resources, contact: Nature of the Northwest Information Center 800 NE Oregon Street #5 Portland, Oregon 97232 (971) 673-1555 http://www.naturenw.org Oregon Department of Geology and Mineral Industries - Oregon Geologic Digital Compilation i RULES FOR LITHOLOGY MERGE INFORMATION ENTRY The lithology merge unit contains 5 parts, separated by periods: Major characteristic.Lithology.Layering.Crystals/Grains.Engineering Lithology Merge Unit label (Lith_Mrg_U field in GIS polygon file): major_characteristic.LITHOLOGY.Layering.Crystals/Grains.Engineering major characteristic - lower case, places the unit into a general category .LITHOLOGY - in upper case, generally the compositional/common chemical lithologic name(s)
    [Show full text]
  • A Systematic Nomenclature for Metamorphic Rocks
    A systematic nomenclature for metamorphic rocks: 1. HOW TO NAME A METAMORPHIC ROCK Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: Web version 1/4/04. Rolf Schmid1, Douglas Fettes2, Ben Harte3, Eleutheria Davis4, Jacqueline Desmons5, Hans- Joachim Meyer-Marsilius† and Jaakko Siivola6 1 Institut für Mineralogie und Petrographie, ETH-Centre, CH-8092, Zürich, Switzerland, [email protected] 2 British Geological Survey, Murchison House, West Mains Road, Edinburgh, United Kingdom, [email protected] 3 Grant Institute of Geology, Edinburgh, United Kingdom, [email protected] 4 Patission 339A, 11144 Athens, Greece 5 3, rue de Houdemont 54500, Vandoeuvre-lès-Nancy, France, [email protected] 6 Tasakalliontie 12c, 02760 Espoo, Finland ABSTRACT The usage of some common terms in metamorphic petrology has developed differently in different countries and a range of specialised rock names have been applied locally. The Subcommission on the Systematics of Metamorphic Rocks (SCMR) aims to provide systematic schemes for terminology and rock definitions that are widely acceptable and suitable for international use. This first paper explains the basic classification scheme for common metamorphic rocks proposed by the SCMR, and lays out the general principles which were used by the SCMR when defining terms for metamorphic rocks, their features, conditions of formation and processes. Subsequent papers discuss and present more detailed terminology for particular metamorphic rock groups and processes. The SCMR recognises the very wide usage of some rock names (for example, amphibolite, marble, hornfels) and the existence of many name sets related to specific types of metamorphism (for example, high P/T rocks, migmatites, impactites).
    [Show full text]
  • The Greenschist to Amphibolite Facies Tonalite-Greenstone Terrain of The
    95 THE PIKWITONEI GRANULITE DOMAIN: A LOWER CRUSTAL LEVEL ALONG THE CHURCHILL-SUPERIOR BOUNDARY IN CENTRAL MANITOBA. W. Weber, Manitoba Geological Services Branch, Winnipeg, Manitoba, Canada, R3H OW4 The greenschist to amphibolite facies tonalite-greenstone terrain of the Gods Lake subprovince grades - in a northwesterly direction - into the granulite facies Pikwitonei domain (1) at the western margins of the Superior Province,. The transition is the result of prograde metamorphism and takes place over 50 - 100 km without any structural or lithological breaks. Locally the orthopyroxene isograd is oblique to the structural grain and transects greenstone belts, e.g., the Cross Lake belt (2). The greenstone belts in the granulite facies and adjacent lower grade domain consist mainly of mafic and (minor) ultramafic metavolcanics, and clastic and chemical metasedimentary rocks (1,2). Typical for the greenstone belts crossed by the orthopyroxene isograd are anorthositic gabbros and anorthosites, and plagiophyric mafic flows. Available data suggest a late Aphebian age for the prograde greenschist to granulite facies metamorphism. Peak conditions are reflected by saphirin-bearing and opx-sillimanite quartz gneisses which indicate 10 - 11 kb pressure and temperatures of 900 - 1000°C (2). At its western and northern edge - towards the contact with the Churchill Province - the rocks of the Pikwitonei granulite domain were overprinted by the Hudsonian orogeny; they were deformed, selectively retrogressed and recrystallized under greenschist to amphibolite facies conditions (1,2); locally they were migmatized. The Thompson belt, the Split Lake block and a linear zone south of the Fox River consists of these reworked granulites. Proterozoic rocks of the Circum-Superior belt (3) (apparently) overlie the reworked granulites along the Fox River and in the Thompson belt.
    [Show full text]
  • Metamorphic Rocks
    Metamorphic Rocks Geology 200 Geology for Environmental Scientists Regionally metamorphosed rocks shot through with migmatite dikes. Black Canyon of the Gunnison, Colorado Metamorphic rocks from Greenland, 3.8 Ga (billion years old) Major Concepts • Metamorphic rocks can be formed from any rock type: igneous, sedimentary, or existing metamorphic rocks. • Involves recrystallization in the solid state, often with little change in overall chemical composition. • Driving forces are changes in temperature, pressure, and pore fluids. • New minerals and new textures are formed. Major Concepts • During metamorphism platy minerals grow in the direction of least stress producing foliation. • Rocks with only one, non-platy, mineral produce nonfoliated rocks such as quartzite or marble. • Two types of metamorphism: contact and regional. Metamorphism of a Granite to a Gneiss Asbestos, a metamorphic amphibole mineral. The fibrous crystals grow parallel to least stress. Two major types of metamorphism -- contact and regional Major Concepts • Foliated rocks - slate, phyllite, schist, gneiss, mylonite • Non-foliated rocks - quartzite, marble, hornfels, greenstone, granulite • Mineral zones are used to recognize metamorphic facies produced by systematic pressure and temperature changes. Origin of Metamorphic Rocks • Below 200oC rocks remain unchanged. • As temperature rises, crystal lattices are broken down and reformed with different combinations of atoms. New minerals are formed. • The mineral composition of a rock provides a key to the temperature of formation (Fig. 6.5) Fig. 6.5. Different minerals of the same composition, Al2SiO5, are stable at different temperatures and pressures. Where does the heat come from? • Hot magma ranges from 700-12000C. Causes contact metamorphism. • Deep burial - temperature increases 15-300C for every kilometer of depth in the crust.
    [Show full text]
  • Role of Water in the Formation of Granulite and Amphibolite Facies Rocks Tobacco Root Mountains Montana
    University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1988 Role of water in the formation of granulite and amphibolite facies rocks Tobacco Root Mountains Montana Linda M. Angeloni The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Angeloni, Linda M., "Role of water in the formation of granulite and amphibolite facies rocks Tobacco Root Mountains Montana" (1988). Graduate Student Theses, Dissertations, & Professional Papers. 8115. https://scholarworks.umt.edu/etd/8115 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1976 Th is is an unpublished manuscript in which copyright SUBSISTS. Any further r e p r in t in g of its contents must be APPROVED BY THE AUTHOR. Ma n s f ie l d Library Un iv e r s it y of Montana Date : t , 9 C B_ THE ROLE OF WATER IN THE FORMATION OF GRANULITE AND AMPHIBOLITE FACIES ROCKS, TOBACCO ROOT MOUNTAINS, MONTANA By Linda Marie Angeloni B.S., University of California, Santa Cruz, 1982 Presented in partial fulfillment of the requirements for the degree of Master of Science University of Montana 1988 Approved by Chairman, Board of Examiners Dean, Graduate School Date UMI Number: EP38916 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted.
    [Show full text]
  • Multiple Veining in a Paleo–Accretionary Wedge: the Metamorphic Rock Record of Prograde Dehydration and Transient High Pore- GEOSPHERE, V
    Research Paper THEMED ISSUE: Subduction Top to Bottom 2 GEOSPHERE Multiple veining in a paleo–accretionary wedge: The metamorphic rock record of prograde dehydration and transient high pore- GEOSPHERE, v. 16, no. 3 fluid pressures along the subduction interface (Western Series, https://doi.org/10.1130/GES02227.1 11 figures; 2 tables; 1 set of supplemental files central Chile) Jesús Muñoz-Montecinos1,2,*, Samuel Angiboust1,*, Aitor Cambeses3,*, and Antonio García-Casco2,4,* CORRESPONDENCE: 1 [email protected] Institut de Physique du Globe de Paris, Université de Paris, CNRS, F-75005 Paris, France 2Department of Mineralogy and Petrology, Faculty of Sciences, University of Granada, Campus Fuentenueva s/n, 18002 Granada, Spain 3Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Bochum 44801, Germany CITATION: Muñoz-Montecinos, J., Angiboust, S., 4Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, Armilla, Granada 18100, Spain Cambeses, A., and García-Casco, A., 2020, Multiple veining in a paleo–accretionary wedge: The metamor- phic rock record of prograde dehydration and transient high pore-fluid pressures along the subduction inter- ABSTRACT that the formation of interlayered blueschist and fluid-rock interaction events (Zack and John, 2007). face (Western Series, central Chile): Geosphere, v. 16, greenschist layers in Pichilemu metavolcanics is a Textures recorded in veins yield information on no. 3, p. 765–786, https://doi.org/10.1130/GES02227.1. High pressure–low temperature metamorphic consequence of local bulk composition variations, crack aperture as well as crystal growth kinetics rocks from the late Paleozoic accretionary wedge and that greenschists are generally not formed due during each veining event (Cox and Etheridge, 1983; Science Editor: Shanaka de Silva exposed in central Chile (Pichilemu region) are to selective exhumation-related retrogression of Bons, 2001), while vein-filling mineral assemblages Guest Associate Editor: Gray E.
    [Show full text]
  • Geologic Map of Washington - Northwest Quadrant
    GEOLOGIC MAP OF WASHINGTON - NORTHWEST QUADRANT by JOE D. DRAGOVICH, ROBERT L. LOGAN, HENRY W. SCHASSE, TIMOTHY J. WALSH, WILLIAM S. LINGLEY, JR., DAVID K . NORMAN, WENDY J. GERSTEL, THOMAS J. LAPEN, J. ERIC SCHUSTER, AND KAREN D. MEYERS WASHINGTON DIVISION Of GEOLOGY AND EARTH RESOURCES GEOLOGIC MAP GM-50 2002 •• WASHINGTON STATE DEPARTMENTOF 4 r Natural Resources Doug Sutherland· Commissioner of Pubhc Lands Division ol Geology and Earth Resources Ron Telssera, Slate Geologist WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES Ron Teissere, State Geologist David K. Norman, Assistant State Geologist GEOLOGIC MAP OF WASHINGTON­ NORTHWEST QUADRANT by Joe D. Dragovich, Robert L. Logan, Henry W. Schasse, Timothy J. Walsh, William S. Lingley, Jr., David K. Norman, Wendy J. Gerstel, Thomas J. Lapen, J. Eric Schuster, and Karen D. Meyers This publication is dedicated to Rowland W. Tabor, U.S. Geological Survey, retired, in recognition and appreciation of his fundamental contributions to geologic mapping and geologic understanding in the Cascade Range and Olympic Mountains. WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES GEOLOGIC MAP GM-50 2002 Envelope photo: View to the northeast from Hurricane Ridge in the Olympic Mountains across the eastern Strait of Juan de Fuca to the northern Cascade Range. The Dungeness River lowland, capped by late Pleistocene glacial sedi­ ments, is in the center foreground. Holocene Dungeness Spit is in the lower left foreground. Fidalgo Island and Mount Erie, composed of Jurassic intrusive and Jurassic to Cretaceous sedimentary rocks of the Fidalgo Complex, are visible as the first high point of land directly across the strait from Dungeness Spit.
    [Show full text]
  • Glossary of Geological Terms
    GLOSSARY OF GEOLOGICAL TERMS These terms relate to prospecting and exploration, to the regional geology of Newfoundland and Labrador, and to some of the geological environments and mineral occurrences preserved in the province. Some common rocks, textures and structural terms are also defined. You may come across some of these terms when reading company assessment files, government reports or papers from journals. Underlined words in definitions are explained elsewhere in the glossary. New material will be added as needed - check back often. - A - A-HORIZON SOIL: the uppermost layer of soil also referred to as topsoil. This is the layer of mineral soil with the most organic matter accumulation and soil life. This layer is not usually selected in soil surveys. ADIT: an opening that is driven horizontally (into the side of a mountain or hill) to access a mineral deposit. AIRBORNE SURVEY: a geophysical survey done from the air by systematically crossing an area or mineral property using aircraft outfitted with a variety of sensitive instruments designed to measure variations in the earth=s magnetic, gravitational, electro-magnetic fields, and/or the radiation (Radiometric Surveys) emitted by rocks at or near the surface. These surveys detect anomalies. AIRBORNE MAGNETIC (or AEROMAG) SURVEYS: regional or local magnetic surveys that measures deviations in the earth=s magnetic field and carried out by flying a magnetometer along flight lines on a pre-determined grid pattern. The lower the aircraft and the closer the flight lines, the more sensitive is the survey and the more detail in the resultant maps. Aeromag maps produced from these surveys are important exploration tools and have played a major role in many major discoveries (e.g., the Olympic Dam deposit in Australia).
    [Show full text]