DOCSLIB.ORG

Investigation of the High-Pressure Behavior of Amphiboles

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

INVESTIGATION OF THE HIGH-PRESSURE BEHAVIOR OF AMPHIBOLES A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERISTY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN EARTH AND PLANETARY SCIENCES MAY 2019 By TOMMY W. YONG Thesis Committee: Przemyslaw Dera, Chairperson Bin Chen Julia E. Hammer Keywords: Amphibole, phase transition, high pressure, single-crystal X-ray diffraction, crystallography, diamond anvil cell, synchrotron source Acknowledgements It has been my greatest privilege to have had the opportunity to conduct this research as a student of the University of Hawai‘i at Mānoa. I owe my deepest gratitude to my advisor, Dr. Przemyslaw Dera, without whom it would not have been possible to complete this work. He opened my eyes to the field of high-pressure crystallography, for which I am eternally grateful for. It has been an absolute pleasure working with him over the last two years. Additionally, I am extremely thankful for my committee members, Dr. Bin Chen and Dr. Julia E. Hammer, who provided valuable feedback throughout this project. I am tremendously grateful to have had the opportunity to take classes from the both of you and the knowledge that you both have imparted on me has been invaluable towards the completion of this thesis. I also owe a great debt of gratitude to Dr. Robert Downs and Dr. Hexiong Yang for inspiring me to continue my education in the geosciences and for their mentorship during my undergraduate studies. Many thanks go to my research group, Dr. Hannah Shelton, Dr. Dongzhou Zhang, Dr. Gregory Finkelstein, Dr. Yi Hu and May Chornkrathok for serving as role models, colleagues and friends throughout my time in Hawai‘i and Chicago. I would like to thank the support from the Fred M. Bullard Endowed Graduate Fellowship, National Science Foundation Grant EAR-1722969 and EAR-1541516, the Department of Earth Sciences at the University of Hawai‘i at Mānoa and Hawai‘i Institute of Geophysics and Planetology. Lastly, this thesis would not have been possible without the support of my parents and wife-to-be, Lauren Ward. You are my greatest supporters, my pillar of strength and my inspiration, without you none of this would have been possible. i Abstract Amphibole group minerals are important constituents in many metamorphic and igneous rocks. They have an unusually high chemical variety, which allows them to be used as petrogenetic indicators. Owing to their structural and chemical complexity, developments on quantitative descriptions of amphiboles have been hindered. High-pressure structural studies using a synchrotron X-ray source were conducted on two different amphibole mineral species, namely, grunerite (Fe7Si8O22(OH)2) and gedrite (Mg2(Mg3Al2)(Si6Al2)O22(OH)2). In both minerals, new pressure-induced displacive phase transitions are observed around 20 GPa that closely mirror the phase-transition sequences known in pyroxenes. The phase transitions are characterized by a greater degree of kinking in the double silicate chains of tetrahedra. The experimental findings of this study demonstrate the parallel pressure-induced phase transformation behavior between amphiboles and pyroxenes, suggesting that structures with comparable topology behave similarly in response to high-pressure. In the lithospheric mantle, amphiboles are the most abundant hydrous species, consequently they play an important role in numerous petrological and geophysical processes, such as partial melting and devolatilization. The geophysical implications of the experimental findings of this study are discussed in terms of subducting slabs along disequilibrium pathways that deviate from an average mantle geotherm. The metastable persistence of amphibole group minerals into higher-pressure regimes may have possible implications towards slab buoyancy or as a potential trigger for seismic events. ii Table of Contents Acknowledgements ...................................................................................................................... i Abstract ...................................................................................................................................... ii List of Tables ............................................................................................................................. iv List of Figures ............................................................................................................................. v Chapter 1. Introduction ..................................................................................................... 1 1.1 Thesis Overview ....................................................................................................... 1 1.2 Introduction to Amphiboles ...................................................................................... 2 1.3 Overview of Common Amphibole Crystal Structures .............................................. 3 Chapter 2. Single crystal X-ray Diffraction of Grunerite up to 25.6 GPa: A New High-Pressure Clinoamphibole Polymorph ................................................. 9 2.1 Introduction ............................................................................................................. 10 2.2 Experimental Procedures ........................................................................................ 11 2.3 Results and Discussion ........................................................................................... 16 2.4 Implications............................................................................................................. 22 2.5 Tables and Figures .................................................................................................. 25 Chapter 3. A New High-Pressure Phase Transition in Natural Gedrite ........ 33 3.1 Introduction ............................................................................................................. 34 3.2 Experimental Procedures ........................................................................................ 35 3.3 Results ..................................................................................................................... 40 3.4 Discussion ............................................................................................................... 44 3.5 Tables and Figures .................................................................................................. 50 Chapter 4. Conclusions and Future Work ................................................................ 60 References ............................................................................................................................. 63 iii List of Tables 2.1 Microprobe analyses of grunerite ....................................................................................... 25 2.2 Single-crystal structure refinement details .......................................................................... 26 2.3 Unit cell parameters of grunerite ........................................................................................ 26 2.4 Atomic positional coordinates of grunerite ......................................................................... 27 2.5 Bond lengths of grunerite.................................................................................................... 28 2.6 Equation of state data for grunerite ..................................................................................... 28 3.1 Microprobe analyses of gedrite ........................................................................................... 50 3.2 Microprobe analyses of standards ....................................................................................... 51 3.3 Hydrogen bond distances .................................................................................................... 51 3.4 Single-crystal structure refinement details .......................................................................... 51 3.5 Atomic positional coordinates of gedrite ............................................................................ 52 3.6 Anisotropic displacement parameters of gedrite ................................................................. 55 3.7 Unit cell parameters of gedrite ............................................................................................ 55 3.8 Polyhedra volumes and distortion parameters of gedrite .................................................... 56 iv List of Figures 1.1 C2/m amphibole structure ..................................................................................................... 5 1.2 Pnma amphibole structure .................................................................................................... 7 1.3 P21/m amphibole structure .................................................................................................... 8 2.1 Grunerite (α, β, γ) crystal structure ..................................................................................... 29 2.2 Normalized unit cell parameters of grunerite ..................................................................... 30 2.3 Chain displacement factor in grunerite ............................................................................... 30 2.4 Unit cell volume of grunerite .............................................................................................. 30 2.5 Kinking angle of grunerite .................................................................................................. 30 2.6
Recommended publications
  • AMPHIBOLES: Crystal Chemistry, Occurrence, and Health Issues

    AMPHIBOLES: Crystal Chemistry, Occurrence, and Health Issues

    AMPHIBOLES: Crystal Chemistry, Occurrence, and Health Issues 67 Reviews in Mineralogy and. Geochemistry 67 TABLE OF CONTENTS 1 Amphiboles: Crystal Chemistry Frank C. Hawthorne, Roberta Oberti INTRODUCTION 1 CHEMICAL FORMULA 1 SOMi : ASPECTS OF CHEMICAL ANALYSIS 1 Chemical composition 1 Summary 6 CALCULATION OF THE CHEMICAL FORMULA 7 24 (O, OH, F, CI) 7 23 (O) 8 13 cations 8 15 cations 8 16 cations 8 Summary 8 AMPIIIBOI I S: CRYSTAL STRUCTURE 8 Space groups 9 Cell dimensions 9 Site nomenclature 9 The C2/m amphibole structure 10 The P2/m amphibole structure 12 The P2/a amphibole structure 12 The Pnma amphibole structure 12 The Pnmn amphibole structure 14 The C1 amphibole structure 17 STACKING SEQUENCES AND SPACE GROUPS 18 BOND LENGTHS AND BOND VALENCES IN [4IA1-FREE AMPHIBOLES 19 THE DOUBLE-CHAIN OF TETRAHEDRA IN [4IA1 AMPHIBOLES 19 Variation in <T-0> bondlengths in C2/m amphiboles 21 Variation in <T-0> bondlengths in Pnma amphiboles 25 THE STEREOCHEMISTRY OF THE STRIP OF OCTAHEDRA 27 The C2/m amphiboles: variation in mean bondlengths 27 The Pnma amphiboles with B(Mg,Fe,Mn): variation in mean bondlengths 30 v Amphiboles - Table of Contents The Pnma amphiboles with BLi: variation in mean bondlengths 32 THE STEREOCHEMISTRY OF THE M (4) SITE 34 The calcic, sodic-calcic and sodic amphiboles 35 Amphiboles with small B cations (magnesium-iron-manganese- lithium, magnesium-sodium and lithium-sodium) 36 The C2/m amphiboles: variation in <M(4)-0> bondlengths 36 The Pnma amphiboles: variation in <MA-0> bondlengths 36 I III! STEREOCHEMISTRY OF THE A SITE 37 The C2/m amphiboles 37 The PU a amphibole 40 The Pnma amphiboles 40 The Pnmn amphiboles 41 THE STEREOCHEMISTRY OF THE 0(3) SITE 41 The C2/m amphiboles 41 UNIT-CELL PARAMETERS AND COMPOSITION IN C2/m AMPHIBOLES 42 SUMMARY 46 ACKNOWLEDGMENTS 46 REFERENCES 47 APPENDIX 1: CRYSTAL-STRUCTURE REFINEMENTS OF AMPHIBOLE 51 Z Classification of the Amphiboles Frank C.
  • Depositional Setting of Algoma-Type Banded Iron Formation Blandine Gourcerol, P Thurston, D Kontak, O Côté-Mantha, J Biczok

    Depositional Setting of Algoma-Type Banded Iron Formation Blandine Gourcerol, P Thurston, D Kontak, O Côté-Mantha, J Biczok

    Depositional Setting of Algoma-type Banded Iron Formation Blandine Gourcerol, P Thurston, D Kontak, O Côté-Mantha, J Biczok To cite this version: Blandine Gourcerol, P Thurston, D Kontak, O Côté-Mantha, J Biczok. Depositional Setting of Algoma-type Banded Iron Formation. Precambrian Research, Elsevier, 2016. hal-02283951 HAL Id: hal-02283951 https://hal-brgm.archives-ouvertes.fr/hal-02283951 Submitted on 11 Sep 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Accepted Manuscript Depositional Setting of Algoma-type Banded Iron Formation B. Gourcerol, P.C. Thurston, D.J. Kontak, O. Côté-Mantha, J. Biczok PII: S0301-9268(16)30108-5 DOI: http://dx.doi.org/10.1016/j.precamres.2016.04.019 Reference: PRECAM 4501 To appear in: Precambrian Research Received Date: 26 September 2015 Revised Date: 21 January 2016 Accepted Date: 30 April 2016 Please cite this article as: B. Gourcerol, P.C. Thurston, D.J. Kontak, O. Côté-Mantha, J. Biczok, Depositional Setting of Algoma-type Banded Iron Formation, Precambrian Research (2016), doi: http://dx.doi.org/10.1016/j.precamres. 2016.04.019 This is a PDF file of an unedited manuscript that has been accepted for publication.
  • Module 7 Igneous Rocks IGNEOUS ROCKS

    Module 7 Igneous Rocks IGNEOUS ROCKS

    Module 7 Igneous Rocks IGNEOUS ROCKS ▪ Igneous Rocks form by crystallization of molten rock material IGNEOUS ROCKS ▪ Igneous Rocks form by crystallization of molten rock material ▪ Molten rock material below Earth’s surface is called magma ▪ Molten rock material erupted above Earth’s surface is called lava ▪ The name changes because the composition of the molten material changes as it is erupted due to escape of volatile gases Rocks Cycle Consolidation Crystallization Rock Forming Minerals 1200ºC Olivine High Ca-rich Pyroxene Ca-Na-rich Amphibole Intermediate Na-Ca-rich Continuous branch Continuous Discontinuous branch Discontinuous Biotite Na-rich Plagioclase feldspar of liquid increases liquid of 2 Temperature decreases Temperature SiO Low K-feldspar Muscovite Quartz 700ºC BOWEN’S REACTION SERIES Rock Forming Minerals Olivine Ca-rich Pyroxene Ca-Na-rich Amphibole Na-Ca-rich Continuous branch Continuous Discontinuous branch Discontinuous Biotite Na-rich Plagioclase feldspar K-feldspar Muscovite Quartz BOWEN’S REACTION SERIES Rock Forming Minerals High Temperature Mineral Suite Olivine • Isolated Tetrahedra Structure • Iron, magnesium, silicon, oxygen • Bowen’s Discontinuous Series Augite • Single Chain Structure (Pyroxene) • Iron, magnesium, calcium, silicon, aluminium, oxygen • Bowen’s Discontinuos Series Calcium Feldspar • Framework Silicate Structure (Plagioclase) • Calcium, silicon, aluminium, oxygen • Bowen’s Continuous Series Rock Forming Minerals Intermediate Temperature Mineral Suite Hornblende • Double Chain Structure (Amphibole)
  • Chemographic Exploration of Amphibole Assemblages from Central Massachusetts and Southwestern New Hampshire

    Chemographic Exploration of Amphibole Assemblages from Central Massachusetts and Southwestern New Hampshire

    Mineral. Soc. Amer, Spec. Pap. 2, 251-274 (1969). CHEMOGRAPHIC EXPLORATION OF AMPHIBOLE ASSEMBLAGES FROM CENTRAL MASSACHUSETTS AND SOUTHWESTERN NEW HAMPSHIRE PETER ROBINSON AND HOWARD W. JAFFE Department of Geology, University of Massachusetts, Amherst, Massachusetts 01002 ABSTRACT Fourteen wet chemical and forty electron-probe analyses were made of amphiboles from critical assemblages in the kyanite and sillimanite zones of central Massachusetts and southwestern New Hampshire. The rocks studied in- clude plagioclase amphibolites that are metamorphosed mafic lavas and tuffs, aluminous anthophyllite rocks of uncertain derivation, quartz-garnet-amphibole granulites that are metamorphosed ferruginous cherts, and pods of ultramafic amphibolite. The rocks contain the following associations: hornblende-anthophyllite, hornblende-cummingtonite, anthophyllite-cummingtonite, hornblende-anthophyllite-cummingtonite, anthophyllite-cordierite, and anthophyllite- kyanite-sillimanite-staurolite_garnet. The following generalizations are made: 1) The cummingtonites are compositionally simple, containing neither sig- nificant AI/AI, NaJAI, nor Ca substitution. 2) The hornblendes are high in AI/AI substitution. Those coexisting with cummingtonite in the kyanite zone or in retrograded rocks have a higher Al content than those coexisting with cum- mingtonite in the sillimanite zone, in close agreement with the prograde reaction tschermakitic hornblende -7 cumming- tonite + plagioclase + H20 proposed by Shido. The Na content of hornblende is considerably less than that of the theoretical edenite end member and is relatively insensitive to variation in the Na content of coexisting plagioclase. 3) Anthophyllites coexisting with hornblende contain about 1as much AI/AI substitution and 1as much Na substitution as coexisting hornblendes. Ca is negligible. Anthophyllites with cordierite, aluminosilicates, or garnet equal or surpass hornblende in AI/AI and Na substitution.
  • Optical Properties of Common Rock-Forming Minerals

    Optical Properties of Common Rock-Forming Minerals

    AppendixA __________ Optical Properties of Common Rock-Forming Minerals 325 Optical Properties of Common Rock-Forming Minerals J. B. Lyons, S. A. Morse, and R. E. Stoiber Distinguishing Characteristics Chemical XI. System and Indices Birefringence "Characteristically parallel, but Mineral Composition Best Cleavage Sign,2V and Relief and Color see Fig. 13-3. A. High Positive Relief Zircon ZrSiO. Tet. (+) 111=1.940 High biref. Small euhedral grains show (.055) parallel" extinction; may cause pleochroic haloes if enclosed in other minerals Sphene CaTiSiOs Mon. (110) (+) 30-50 13=1.895 High biref. Wedge-shaped grains; may (Titanite) to 1.935 (0.108-.135) show (110) cleavage or (100) Often or (221) parting; ZI\c=51 0; brownish in very high relief; r>v extreme. color CtJI\) 0) Gamet AsB2(SiO.la where Iso. High Grandite often Very pale pink commonest A = R2+ and B = RS + 1.7-1.9 weakly color; inclusions common. birefracting. Indices vary widely with composition. Crystals often euhedraL Uvarovite green, very rare. Staurolite H2FeAI.Si2O'2 Orth. (010) (+) 2V = 87 13=1.750 Low biref. Pleochroic colorless to golden (approximately) (.012) yellow; one good cleavage; twins cruciform or oblique; metamorphic. Olivine Series Mg2SiO. Orth. (+) 2V=85 13=1.651 High biref. Colorless (Fo) to yellow or pale to to (.035) brown (Fa); high relief. Fe2SiO. Orth. (-) 2V=47 13=1.865 High biref. Shagreen (mottled) surface; (.051) often cracked and altered to %II - serpentine. Poor (010) and (100) cleavages. Extinction par- ~ ~ alleL" l~4~ Tourmaline Na(Mg,Fe,Mn,Li,Alk Hex. (-) 111=1.636 Mod. biref.
  • (Fe-Mg Amphibole) in Plutonic Rocks of Nahuelbuta Mountains

    (Fe-Mg Amphibole) in Plutonic Rocks of Nahuelbuta Mountains

    U N I V E R S I D A D D E C O N C E P C I Ó N DEPARTAMENTO DE CIENCIAS DE LA TIERRA 10° CONGRESO GEOLÓGICO CHILENO 2003 THE OCCURRENCE AND THERMAL DISEQUILIBRIUM OF CUMMINGTONITE IN PLUTONIC ROCKS OF NAHUELBUTA MOUNTAINS CREIXELL, C.(1*); FIGUEROA, O.(1); LUCASSEN, F.(2,3), FRANZ, G.(4) & VÁSQUEZ, P.(1) (1)Universidad de Concepción, Chile, Depto. Ciencias de la Tierra, Barrio Universitario s/n, casilla 160-C (2)Freie Universität Berlin, FB Geowissenschaften, Malteserstr. 74-100, 12249 Berlin, Germany (3)GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany; [email protected] (4)TU-Berlin, Petrologie-EB15, Strasse des 17.Juni 135, 10623 Berlin, Germany; *Present Address: MECESUP-Universidad de Chile, Depto. de Geología, Plaza Ercilla 803, casilla 13518, [email protected] INTRODUCTION The “cummingtonite series” (Leake, 1978) are characterised by magnesio-cummingtonite (Mg7Si8O22(OH)2) and grunerite (Fe7Si8O22(OH)2) end-members. Cummingtonite is mainly produced under amphibolite-facies conditions, but the entire stability range cover at least a field of 400 to 800° C, at pressures between <1 to 15 kbar (Evans and Ghiorso, 1995, Ghiorso et al., 1995). Natural cummingtonite occurs in several metamorphic rock types (i.e. Kisch & Warnaars, 1969, Choudhuri, 1972) and also can coexist with incipient melt in high-grade gneisses in deep- crustal levels (Kenah and Hollister, 1983). For igneous rocks, cummingtonite had been described in some rhyolites at Taupo Zone, New Zealand (Wood & Carmichael, 1973) and as a stable phase in plutonic rocks (e.g. Bues et al., 2002). In the present study, we describe the occurrence of cummingtonite in Upper Palaeozoic plutonic rocks and their amphibolite xenoliths from the Nahuelbuta Mountains, south central Chile (37°-38°S, for location see fig.
  • Pyroxenes, Amphibole, and Mica from the Tiree Marble. 1 (With Plate XIV.)

    Pyroxenes, Amphibole, and Mica from the Tiree Marble. 1 (With Plate XIV.)

    230 Pyroxenes, amphibole, and mica from the Tiree marble. 1 (With Plate XIV.) By A. F. HALLIMOND,M.A., Sc.D. With chemical analyses by C. O. HARVEY, B.Sc., A.R.C.S. [Read March 27, 1947.] I. INTRODUCTION. HE Tiree pink marble, a fine-grained, severely crushed limestone T with evidence of earlier coarse crystallization, is exposed in several small areas up to 100 feet across on the farm of Balephetrish near the north coast of the island of Tiree in the Hebrides. It contains a r~mark- able quantity of dark silicate minerals and has discordant contacts with the adjacent Lewisian gneiss. The precise nature of its relation to the gneiss, and mode of emplacement, have been much discussed. ~ The writer has been permitted to consult accounts of the literature, by Mr. V. A. Eyles, and of the petrography, by Sir Edward B. Bailey, and is also indebted to those authors for discussion of the problems. At the suggestion of Sir Edward Bailey the present work was undertaken as a contribution to the study of this problem from the mineralogical point of view. Most of the determinations were made in 1938, but it was not possible to complete publication at that time. Scattered somewhat evenly throughout the carbonate groundmass of the marble are numerous dark green crystalline patches which usually do not exceed half an inch across and are often much smaller; locally, however, there are pieces of dark gneiss-like rock of much larger size. The majority consist of pyroxene, sometimes accompanied by amphi- bole, &c., and the latter were regarded by Coom~rasw~my and others as modified gneiss inclusions.
  • ASBESTOS: MINERALOGY, HEALTH HAZARDS and PUBLIC POLICY Helen M

    ASBESTOS: MINERALOGY, HEALTH HAZARDS and PUBLIC POLICY Helen M

    ASBESTOS: MINERALOGY, HEALTH HAZARDS AND PUBLIC POLICY Helen M. Lang Department of Geology and Geography West Virginia University P.O. Box 6300 Morgantown, West Virginia 26506-6300 [email protected] Sid P. Halsor Department of GeoEnvironmental Science & Engineering Wilkes University Wilkes-Barre, Pennsylvania 18766 [email protected] BACKGROUND Asbestos refers to certain minerals that have a fibrous habit and are useful for their insulating, heat and chemically resistant properties. Asbestos has been used extensively for over a century in electrical and heat insulation, fireproofing materials, brake and clutch linings, construction materials, filters and many other applications. Recently, the U.S. has severely restricted the use of asbestos, and has a program for removing asbestos from schools and other public buildings (See Gunter, 1994; Ross, 1995 and references therein). In this laboratory exercise you will have an opportunity to examine the crystal structures, optical properties and health hazards of the common asbestos minerals. The laboratory will reinforce optical microscopic skills that you have learned in mineralogy and show you how mineralogy can be critical to understanding a current public policy issue. Although mineralogists reserve the designation asbestos for fibrous material with a length:width ratio (aspect ratio) of at least 10: 1 (Skinner, et al., 1988), asbestos is defined by OSHA (U.S. Occupational Safety and Health Administration, 1972; Web address is given below) as mineral material composed of any of the six silicate minerals in Table 1 with a length:width ratio of3:1 or greater, diameter less than 5 µm and length greater than 5 µm. Table 1.
  • Crystallization and Metasomatism of Nepheline Syenite Xenoliths in Quartz-Bearing Intrusive Rocks in the Permian Oslo Rift, SE Norway

    Crystallization and Metasomatism of Nepheline Syenite Xenoliths in Quartz-Bearing Intrusive Rocks in the Permian Oslo Rift, SE Norway

    Crystallization and metasomatism of nepheline syenite xenoliths in quartz-bearing intrusive rocks in the Permian Oslo rift, SE Norway TOM ANDERSEN & HENNING SØRENSEN Andersen, T. & Sørensen, H.: Crystallization and metasomatism of nepheline syenite xenoliths in quartz-bearing intrusive rocks in the Permian Oslo rift, SE Norway. Norsk Geologisk Tidsskrift, Vol. 73, pp. 250-266. Oslo 1993. ISSN 0029-196X. Small bodies of metasomatized nepheline syenite occur as xenoliths in syenitic and granitic intrusions in the Mykle area, ca. 30 km N of the Larvik pluton in the Vestfold Graben of the late Paleozoic Qslo rift of SE Norway. The nepheline syenite has a metaluminous major element composition, and its primary igneous mineralogy is: alkali feldspar + nepheline + clinopyroxene + titanite + magnetite + apatite ± amphibole. The mafic silicate minerals have lower (Na + K)/AI than comparable minerals in other fe lsic intrusions in the Oslo Rift. Gamet (grossular-andradite), analcime, sodalite, thomsonite and gonnardite occur as interstitial minerals in the )east altered parts of the nepheline syenite. The xenoliths were metasomatized as a result of interaction between nepheline syenite and younger silica-saturated to oversaturated magrnas and their associated fluids. Early, pervasive metasomatism led to breakdown of nepheline, replacement of pyroxene by biotite ± garnet and crystallization of quartz. Recrystallization took place at solidus-near temperatures (700-725°C), and was controlled by an increase in silica activity and oxygen fugacity. Titanite + magnetite were replaced by rutile + quartz + hematite + calcite at a late stage of the metasomatic history, at oxygen fugacities above the HM buffer, and T < 450°C. The xenoliths indicate the former presence of larger bodies of nepheline syenite in an area where no such rocks were known previously.
  • A Systematic Nomenclature for Metamorphic Rocks

    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).
  • Grunerite from the Shinyama Ore Deposit, Kamaishi Mine

    Grunerite from the Shinyama Ore Deposit, Kamaishi Mine

    Canadian Mineralogist Vol. 21, pp. 517-528(1983) GRUNERITEFROM THE SHINYAMA ORE DEPOSIT,KAMAISHI MINE, JAPAN ETSUO UCHIDA,8 GeologicalInstitute, Facalty of Scienc?,University of Tokyo, 7-3-l Hongo, Bunkyo-ku, Tokyo 113,Japan ABSTRACT on compositionsof amphibole determinedby the electron-probemicroanalyzer, reveals that most are, Most of the clinopyroxenein the clinopyroxeneskam that in fact, cummingtonite-grunerite containing only a contains the 4D copper orebody of the Shinyama ore small calcium component,Grunerite is common in deposit(Japan) was alteredto amphibole owing to late-stage metamorphosediron-formations (cl, Mueller 1960), decreaseoftemperature. Two amphibole speciesare found: Ca-amphibole and cummingtonite-grunerite; the latter is and cummingtonite is widespreadin metabasicrocks rarely found in skarn-typeore deposits.In exoskarnsderiv- in the amphibolite facies. But cummingtonite- ed from limestone, the following zonal arrangementis grunerite is rare.in skarn-typeore deposits.In this observed from the limestone to the igneous rock: paper, the amphibolesoccurring in skarns around cummingtonite-grunerite skarn, Ca-amphibole skarn, the 4D orebody of the Shinyamadeposit are describ- (clinopyroxene skarn) and garnet skarn. This arrangement ed, and their thermochemicalconditions of forma- is attributable to the increasein the chemicalpotential of tion are elucidated. CO2 toward the limestone. GEOLoGYoF THE KAMATSHIMINING Keywords: cummingtonite-grunerite, Kamaishi mine, Shinyama deposit, skarn, zonal arrangement,phase Drsrnrcr ANDDEscRrprroN
  • The Stability of Amphibole in Andesite and Basalt at High Pressuresr

    The Stability of Amphibole in Andesite and Basalt at High Pressuresr

    American Mineralogist, Volume 68, pages 307-314, 1983 The stability of amphibole in andesiteand basalt at high pressuresr J. C. Alt-BN Department of Geology and Geography Bucknell University Lewisburg, Pennsylvania 17837 exo A. L. Bonrrcsen Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences University of Califurnia, Los Angeles Los Angeles, California 90024 Abstract Some of our earlier work (Allen et al., 1975)on the stability of amphibolesin andesite and basalt at high pressuresis subject to criticism becauseofloss ofiron from the starting material to the walls of the capsules(AgsoPdso) during the runs of/6, bufered over the range of stability of magnetite.Analyses of fused run products show substantialloss of iron from runs at magnetite-wiistite and nickel-nickel oxide conditions, but none from those at magnetite-hematiteconditions. We have now redone our earlier work on the Mt. Hood andesiteand l92l Kilauea olivine tholeiite under N-NO conditions and with silver capsules.Analyses of fused run products show no iron loss, and the reversed curve representing the maximum stability of the amphibolesin the Mt. Hood andesiteshows no changein location, although we now have better control on the high-pressurepart of this curve. The revised curve for the appetrance of garnet is significantly lower in pressure, passing through 15.5 kbar/940'C and 14.5 kbar/9fi)'C. No orthopyroxene appearedin the run products, in contrast to the results of our earlier work. The high-temperature segment of the amphibole-out curve for the tholeiite is at least as high as 1040'Cat 13kbar and 1050"Cat 16kbar, and the high-pressure part of this curve is at about 27 kbars, about 6 kbar higher than in our earlier work.