DOCSLIB.ORG

Crystal Structure Dynamics: Evidence by Diffraction and Spectroscopy

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Crystal Structure Dynamics: Evidence by Diffraction and Spectroscopy CROATICA CHEMICA ACTA CCACAA 79 (2) 299¿309 (2006) ISSN-0011-1643 CCA-3094 Conference paper Crystal Structure Dynamics: Evidence by Diffraction and Spectroscopy Eugen Libowitzky Institut für Mineralogie und Kristallographie, Universität Wien – Geozentrum, Althanstr. 14, A-1090 Wien, Austria (E-mail: [email protected]) RECEIVED DECEMBER 12, 2005; REVISED MARCH 7, 2006; ACCEPTED MARCH 10, 2006 Bragg diffraction is a major tool to solve and refine crystal structures, though it is limited as results obtained from the bulk sample are averaged in time and space. In contrast, spectroscopy is site sensitive, and thus a probe for local structure with high time and space resolution. Com- Keywords bination of both methods may reveal important additional information on crystal structures hydrogen bonding such as disorder and dynamics, and may even help avoid pitfalls in structure solution. Among disorder the given examples are three minerals, i.e., lawsonite, hemimorphite, leonite, which show phase transition phase transitions from dynamically disordered to ordered structures. Continuous evolution infrared from order to dynamic disorder, however without a phase transition, is found in washing soda. water Finally, examples of proton dynamics in a tetragonal garnet and in minerals with very strong hydroxyl hydrogen bonds are presented. INTRODUCTION man spectroscopy are employed, will never result in full description of a crystal structure. However, since it does Since the first days of X-ray diffraction, crystal structu- not rely on crystalline periodicity, non-crystalline mate- res have been solved and refined using the positions and rials such as gases, liquids, melts, glasses and metamict intensities of Bragg reflections from single-crystal and samples can be investigated. Moreover, because it is si- powder diffraction experiments. Later on, the use of te-specific (a number of spectroscopic methods are even »light« sources different from X-rays, i.e., neutrons, element-sensitive), even defects at low concentrations in electrons, extended the use of diffraction experiments to a host structure and short range order phenomena may crystals with very light elements, e.g., hydrogen-bearing be studied. Finally, the excellent time resolution facili- samples, and micro-samples in an electron microscope. tates resolving dynamic processes much better than dif- However, though the method can give the full image of a fraction.3 crystal structure, information is always based on the more or less strict periodicity (long range order) of the crystal lattice.1 Thus, the data are averaged over the STRUCTURAL INFORMATION FROM SPECTRO- whole sample, both in space and time. Therefore, infor- mation on local disorder (space) and dynamics (time), SCOPY and on defects at only trace concentrations may be limi- Using vibrational spectroscopy, quantitative data can be ted. (The recent method of measuring diffuse X-ray scat- obtained that provide useful structural information in tering2 in the »background« region between the Bragg three ways. Since the band energy (frequency, wave- peaks to address these problems is not considered here.) number) of a vibrational band is dependent on the mass On the other hand, spectroscopy, and in this paper and bond strength of the vibrating unit, e.g., an O–H vibrational spectroscopy such as infrared (IR) and Ra- group, the peak positions provide important data on 300 E. LIBOWITZKY bond lengths, like in the case of hydrogen bonds (see be- 4000 low). Absorption (IR) and scattering experiments (Ra- 3500 man) with polarized radiation on oriented, optically ani- –1 sotropic samples result in data on the spatial orientation of a vibrating unit in a crystal structure (see below). Fi- 3000 nally, by calibration of band intensities in a number of different ways, even information on the amount of a cer- 2500 tain molecular species (down to trace concentration lev- els) in a sample can be obtained (see below). Because IR 2000 spectroscopy is frequently used in the examples given below, these quantitative IR techniques are described briefly (however, they work in a similar way also for Ra- 1500 man spectroscopy). O–H stretching wavenumber / cm 1000 In a basic IR absorption experiment, a beam of IR light (modulated in frequency by a monochromator or in 2.4 2.6 2.8 3.0 3.2 3.4 modern spectrometers by an interferometer) with inten- d(O···O) /Å sity I0 is absorbed by a molecular vibration in the sample and the remaining transmitted intensity I is recorded by 4000 the detector. The basic quantity I/I0 is the transmittance T (usually expressed in [100 %]). However, since it is in 3500 logarithmic relation with thickness d and absorber con- –1 centration c, a more convenient unit is absorbance A =– log T. According to the Beer-Lambert law, A = e ·c·d,it 3000 is in linear relation to sample thickness and absorber 4 concentration; e is the molar absorption coefficient. 2500 Correlation diagrams to derive hydrogen bond lengths from O–H stretching vibrations have been devel- 2000 oped since the 1950s both from theoretical calculations5 6–9 and from empirical studies. In general, hydrogen 1500 bonds can be classified according to their bond lengths, i.e., d(O···O), d(H···O), d(O–H), into very strong (very O–H stretching wavenumber / cm short): d(O···O) < 2.50 Å, strong (short): 2.50 < d < 2.70 1000 Å, and weak (long): d > 2.70 Å with a barely defined 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 10 upper limit beyond 3 Å. Figure 1 shows the positive, d(H···O) /Å curved correlation between O–H stretching wavenumber and O···O / H···O hydrogen bond lengths. The principle Figure 1. Correlation diagram between O···O / H···O hydrogen bond lengths and O–H stretching wavenumbers.9 of this correlation is that with increasing hydrogen bond strength (decreasing H bond length), the H bond accep- tor attracts the proton and thus elongates and weakens lipsoid) in optically anisotropic crystals16 (it is therefore the O–H bond (~ 0.98 Å without H bonding), which in impossible in cubic crystals). According to Figure 2, the turn results in decreased stretching frequency (wavenumber). Further effects that correlate with increa- absorbance components along the principal axes Ax, Ay, sing H bond strength are increasing peak width, and in- Az are in a simple cosine squared relation to the total creasing anharmonicity.4,7,11–14 Besides Figure 1, it is magnitude of the absorbance (as if measured parallel to important for the examples below to realize that stretch- the absorber). Thus, by measurements with IR radiation ing vibrations are observed at 3200–3700 cm–1 for weak polarized parallel to all three main directions, the angles H bonds, at 1600–3200 cm–1 for strong H bonds, and be- and consequently the orientation of the absorber are ob- low 1600 cm–1 for very strong bonds.10 Finally, it must tained. Moreover, the sum of the three components re- be stressed that in addition to H bonding, the cationic sults in total absorbance, which is the correct quantity to environment has also a (minor) influence on the wave- estimate the concentration of the absorber. number of O–H stretching vibrations.15 Information about the concentration of a certain ab- The spatial orientation of an O–H vector (or any sorbing species is obtained by calibration of IR band in- other vibrational direction) can be derived from mea- tensities (preferably band areas are used instead of peak surements with polarized IR radiation along the princi- heights) with different analytical methods. In the case of pal optical directions (the main axes of the indicatrix el- hydrous species and defects in minerals, water contents Croat. Chem. Acta 79 (2) 299¿309 (2006) CRYSTAL STRUCTURE DYNAMICS 301 A simple, illustrating example of the above mentio- ned structural constraints from IR data is given in Figure 3, showing spectra20 acquired with polarized IR radiati- on of the tetragonal hydroxyl-bearing silicate mineral vesuvianite. The spectrum with the electric vector E of the polarized light parallel to c shows a band at ~ 3150 cm–1, which is absent in the spectrum perpendicular to c. Thus, an OH– group with strong hydrogen bonding is expected (using Figure 1, an O···O distance of ~ 2.7Åis derived) with orientation parallel to the c axis. This hy- droxyl group (refined O···O H bond length ~ 2.70 Å) is actually observed by diffraction methods (inset in Figure 3).21 In addition, weak or non-H bonded hydroxyl groups with various cationic environments and different orientations (~ 30° from the c axis) are confirmed by the bands at higher wavenumbers in both spectra. Using the A Figure 2. Sketch of an absorber with total absorbance and band areas (integrated absorbances) and the general cali- components Ax, Ay, Az that can be obtained by polarized IR ab- 19 sorption measurements parallel to main optical directions x, y, z.16 bration trend of Libowitzky and Rossman, a concentra- tion ratio of 1 : 4 between the former and the latter hy- droxyl groups is obtained (please note that the areas are may be calibrated by heating the crushed (and milled) not directly comparable!), which is in excellent agree- sample, and detection of the expelled water vapor by va- ment with the crystal structure refinement.20,21 rious methods.17 Because of water adsorbed at grain sur- faces, results are sometimes inaccurate. Bulk methods, e.g., proton magic angle spinning nuclear magnetic reso- LAWSONITE nance (1H MAS NMR), nuclear reaction analysis (NRA), and secondary ion mass spectrometry (SIMS), Lawsonite, CaAl2Si2O7(OH)2 ·H2O, space group Cmcm, avoid this disadvantage but are available only in rare, is a hydrous high-pressure mineral.
Load more

Recommended publications
  • Heat Capacity of High Pressure Minerals and Phase Equilibria of Cretan Blueschists
    Heat capacity of high pressure minerals and phase equilibria of Cretan blueschists by Matthew Rahn Manon A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Geology) in The University of Michigan 2008 Doctoral Committee: Professor Eric J. Essene, Chair Professor Rebecca Ann Lange Professor Youxue Zhang Associate Professor Steven M. Yalisove Matthew Rahn Manon 2008 Acknowledgments Cheers to all the grad students who have gone and come through CC-Little over the years. Zeb, Steven, Jim, Chris, Katy, Phillip, Franek, Eric, Tom, Darius, Sarah, Sara, Abir, Laura, Casey, Sam, John and anyone else I’ve been to learned something from, or argued something with. From early nights at Dominicks for subductology “seminars” through to the FWC, Michigan has been a fun place to live. Thanks to Anne Hudon, whos made sure I haven’t been able to place myself in inextricable holes. Thanks also to those from earlier in my life. College professors like Ken Hess or Barbara Nimmersheim who, in their very different ways inspired me to explore what it is I know. I’ll always remember time spent with Bob Wiebe who introduced me to the wild unknown of geology. Immeasurable thanks go to Eric Essene. The fieldtrips we took the first few years were good adventures. He’s always put aside his own issues to be there for me to talk to, especially when I didn’t deserve it. Eric’s scientific curiosity, and mental rigor are deservedly well known. His patience with me may be one of his great, unsung virtues.
    [Show full text]
  • 1 Revision 1 1 the High-Pressure Phase of Lawsonite
    1 Revision 1 2 The high-pressure phase of lawsonite: A single crystal study of a key mantle hydrous phase 3 4 Earl O’Bannon III,1* Christine M. Beavers1,2, Martin Kunz2, and Quentin Williams1 5 1Department of Earth and Planetary Sciences, University of California, Santa Cruz, 1156 High 6 Street, Santa Cruz, California 95064, U.S.A. 7 2Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, 8 U.S.A. 9 *Corresponding Author 10 1 11 Abstract 12 Lawsonite CaAl2Si2O7(OH)2·H2O is an important water carrier in subducting oceanic 13 crusts, and the primary hydrous phase in basalt at depths greater than ~80 km. We have 14 conducted high-pressure synchrotron single-crystal x-ray diffraction experiments on natural 15 lawsonite at room temperature up to ~10.0 GPa to study its high-pressure polymorphism. We 16 find that lawsonite remains orthorhombic with Cmcm symmetry up to ~9.3 GPa, and shows 17 nearly isotropic compression. Above ~9.3 GPa, lawsonite becomes monoclinic with P21/m 18 symmetry. Across the phase transition, the Ca polyhedron becomes markedly distorted, and 19 the average positions of the H2O molecules and hydroxyls change. The changes observed in the 20 H-atom positions under compression are different than the low temperature changes in this 21 material. We resolve for the first time the H-bonding configuration of the high-pressure 22 monoclinic phase of lawsonite. A bond valence approach is deployed to determine that the 23 phase transition from orthorhombic to monoclinic is primarily driven by the Si2O7 groups, and in 24 particular it's bridging oxygen atom (O1).
    [Show full text]
  • List of Abbreviations
    List of Abbreviations Ab albite Cbz chabazite Fa fayalite Acm acmite Cc chalcocite Fac ferroactinolite Act actinolite Ccl chrysocolla Fcp ferrocarpholite Adr andradite Ccn cancrinite Fed ferroedenite Agt aegirine-augite Ccp chalcopyrite Flt fluorite Ak akermanite Cel celadonite Fo forsterite Alm almandine Cen clinoenstatite Fpa ferropargasite Aln allanite Cfs clinoferrosilite Fs ferrosilite ( ortho) Als aluminosilicate Chl chlorite Fst fassite Am amphibole Chn chondrodite Fts ferrotscher- An anorthite Chr chromite makite And andalusite Chu clinohumite Gbs gibbsite Anh anhydrite Cld chloritoid Ged gedrite Ank ankerite Cls celestite Gh gehlenite Anl analcite Cp carpholite Gln glaucophane Ann annite Cpx Ca clinopyroxene Glt glauconite Ant anatase Crd cordierite Gn galena Ap apatite ern carnegieite Gp gypsum Apo apophyllite Crn corundum Gr graphite Apy arsenopyrite Crs cristroballite Grs grossular Arf arfvedsonite Cs coesite Grt garnet Arg aragonite Cst cassiterite Gru grunerite Atg antigorite Ctl chrysotile Gt goethite Ath anthophyllite Cum cummingtonite Hbl hornblende Aug augite Cv covellite He hercynite Ax axinite Czo clinozoisite Hd hedenbergite Bhm boehmite Dg diginite Hem hematite Bn bornite Di diopside Hl halite Brc brucite Dia diamond Hs hastingsite Brk brookite Dol dolomite Hu humite Brl beryl Drv dravite Hul heulandite Brt barite Dsp diaspore Hyn haiiyne Bst bustamite Eck eckermannite Ill illite Bt biotite Ed edenite Ilm ilmenite Cal calcite Elb elbaite Jd jadeite Cam Ca clinoamphi- En enstatite ( ortho) Jh johannsenite bole Ep epidote
    [Show full text]
  • What We Know About Subduction Zones from the Metamorphic Rock Record
    What we know about subduction zones from the metamorphic rock record Sarah Penniston-Dorland University of Maryland Subduction zones are complex We can learn a lot about processes occurring within active subduction zones by analysis of metamorphic rocks exhumed from ancient subduction zones Accreonary prism • Rocks are exhumed from a wide range of different parts of subduction zones. • Exhumed rocks from fossil subduction zones tell us about materials, conditions and processes within subduction zones • They provide complementary information to observations from active subduction systems Tatsumi, 2005 The subduction interface is more complex than we usually draw Mélange (Bebout, and Penniston-Dorland, 2015) Information from exhumed metamorphic rocks 1. Thermal structure The minerals in exhumed rocks of the subducted slab provide information about the thermal structure of subduction zones. 2. Fluids Metamorphism generates fluids. Fossil subduction zones preserve records of fluid-related processes. 3. Rheology and deformation Rocks from fossil subduction zones record deformation histories and provide information about the nature of the interface and the physical properties of rocks at the interface. 4. Geochemical cycling Metamorphism of the subducting slab plays a key role in the cycling of various elements through subduction zones. Thermal structure Equilibrium Thermodynamics provides the basis for estimating P-T conditions using mineral assemblages and compositions Systems act to minimize Gibbs Free Energy (chemical potential energy) Metamorphic facies and tectonic environment SubduconSubducon zone metamorphism zone metamorphism Regional metamorphism during collision Mid-ocean ridge metamorphism Contact metamorphism around plutons Determining P-T conditions from metamorphic rocks Assumption of chemical equilibrium Classic thermobarometry Based on equilibrium reactions for minerals in rocks, uses the compositions of those minerals and their thermodynamic properties e.g.
    [Show full text]
  • Decomposition of Kyanite and Solubility of Al2o3 in Stishovite at High Pressure and High Temperature Conditions
    Phys Chem Minerals (2006) 33:711–721 DOI 10.1007/s00269-006-0122-x ORIGINAL PAPER Decomposition of kyanite and solubility of Al2O3 in stishovite at high pressure and high temperature conditions Xi Liu Æ Norimasa Nishiyama Æ Takeshi Sanehira Æ Toru Inoue Æ Yuji Higo Æ Shizue Sakamoto Received: 9 August 2006 / Accepted: 9 October 2006 / Published online: 3 November 2006 Ó Springer-Verlag 2006 Abstract In order to constrain the high-pressure Keywords Al2O3 solubility in stishovite Á Corundum Á behavior of kyanite, multi-anvil experiments have been Kyanite Á Phase equilibrium Á Stishovite carried out from 15 to 25 GPa, and 1,350 to 2,500°C. Both forward and reversal approaches to phase equi- libria were adopted in these experiments. We find that Introduction kyanite breaks down to stishovite + corundum at pressures above ~15 GPa, and stishovite + corundum Kyanite (Ky, Al2SiO5), commonly found in peralumi- should be the stable phase assemblage at the pressure– nous eclogites and amphibolites, has been soundly temperature conditions of the transition zone and the demonstrated to be an important constituent phase for uppermost part of the lower mantle of the Earth, the materials of continental crust and pelagic sediment in agreement with previous multi-anvil experimental at pressures from ~1 to 16 GPa (Irifune et al. 1994; studies and ab initio calculation results, but in dis- Schmidt et al. 2004). Its role at higher pressures, how- agreement with some of the diamond-anvil cell ever, remains unclear. With some preliminary experi- experimental studies in the literature. The Al2O3 sol- ments in a Bridgman–anvil apparatus, Ringwood and ubility in nominally dry stishovite has been tightly Reid (1969) tentatively suggested that Ky appears sta- bracketed by forward and reversal experiments; it is ble up to 15 GPa and 1,000°C.
    [Show full text]
  • Staurolite｜Bearing Gneiss and Re｜Examination of Metamorphic
    Staurolite－bearingJournal gneiss of Mineralogical and re－examination and Petrological of metamorphic Sciences, zonal Volume mapping 99 ,of page the Higo1─ 18, metamorphic2004 terrane 1 Staurolite－bearing gneiss and re－examination of metamorphic zonal mapping of the Higo metamorphic terrane in the Kosa area, central Kyushu, Japan * * ** Kenshi MAKI , Yoshihisa ISHIZAKA and Tadao NISHIYAMA *Graduate School of Science and Technology, Kumamoto University, 2－39－1 Kurokami, Kumamoto 860－8555, Japan **Department of Earth Sciences, Faculty of Science, Kumamoto University, 2－39－1 Kurokami, Kumamoto 860－8555, Japan This paper describes the finding of staurolite－bearing gneiss from the Higo metamorphic terrane and proposes new mineral zones in the Kosa area, Kumamoto Prefecture. Previous mineral zones of the Higo metamorphic terrane proposed by Obata et al. (1994) consist of five zones: Zone A characterized by Chl + Ms, Zone B by Bt + Ms + And, Zone C by Kfs + Sil + Bt, Zone D by Grt + Crd + Bt, and Zone E by Opx in metapelites. They identified three zones from B to D in the Kosa area. However, we found that sillimanite appears together with Grt + Crd, hence this paper shows that Zone C is absent in the Kosa area. New finding of Opx in the southern－ most part of the area made it possible to define three mineral zones; Bt zone, Grt－Crd zone, and Opx zone, in the order of increasing grade from north to south in the Kosa area. Analysis of staurolite－bearing assemblage in a KFMASH system together with textural evidence reveals that the following reactions occurred in the stauro- － lite bearing gneiss in the excess of Kfs, Qtz and H2O: [Sil] Str + Bt = Grt + Crd [Bt] Str = Grt + Crd + Sil Chemographic analysis of these reactions together with Grt－Bt geothermometers shows the metamorphic condition of P = 200 MPa and T = 600－620°C, which is much lower in pressure than that estimated by Osanai et al.
    [Show full text]
  • Electronic Supplementary Material (ESI) for Journal of Analytical Atomic Spectrometry This Journal Is © the Royal Society of Chemistry 2012
    Electronic Supplementary Material (ESI) for Journal of Analytical Atomic Spectrometry This journal is © The Royal Society of Chemistry 2012 ELECTRONIC SUPPLEMENTARY INFORMATION FOR Iron oxidation state in garnet from a subduction setting: a micro-XANES and electron microprobe (“flank method”) comparative study Elisa Borfecchia2, Lorenzo Mino2*, Diego Gianolio2, Chiara Groppo1*, Nadia Malaspina3, Gema Martinez-Criado5, Juan Angel Sans Tresserras5, Stefano Poli4, Daniele Castelli1 and Carlo Lamberti2 1 – Dept. Earth Sciences, University of Torino, via Valperga Caluso 35, I-10125 Torino (Italy) 2 – Dept. of Chemistry, University of Torino, via Giuria 7, I-10125 Torino (Italy); NIS Centre of Excellence and INSTM Centro di Riferimento, via Quarello 11, I-10135, Torino (Italy) 3 – Dept. of Geological Sciences and Geotechnology, Università degli Studi di Milano-Bicocca, Piazza della Scienza 4, I-20126 Milano (Italy) 4 – Dept. of Earth Sciences, Università degli Studi di Milano, via Botticelli 23, I-20133 Milano (Italy) 5 - European Synchrotron Radiation Facility, ID22, 6, rue Jules Horowitz, B.P. 220, F-38043 Grenoble cedex (France) Sample description The studied sample OF2727 is a fine-grained eclogitized metagabbro from the Monviso meta- ophiolite (western Alps), consisting of omphacite, garnet and rutile with minor blue amphibole and very minor lawsonite, talc and jadeite, as described by Groppo and Castelli.1 Garnet occurs as small idioblasts (up to 0.5 mm in diameter) set in a matrix mainly consisting of omphacite. Garnet cores (1a-1e in Fig. S1) are crowded of very small inclusions mostly of omphacite, whereas garnet rims (2a-2c in Fig. S1) are almost free of inclusions. Both SEM-EDS and EMP analytical techniques have been used to analyze the major element concentrations across garnet crystals.
    [Show full text]
  • Identification Tables for Common Minerals in Thin Section
    Identification Tables for Common Minerals in Thin Section These tables provide a concise summary of the properties of a range of common minerals. Within the tables, minerals are arranged by colour so as to help with identification. If a mineral commonly has a range of colours, it will appear once for each colour. To identify an unknown mineral, start by answering the following questions: (1) What colour is the mineral? (2) What is the relief of the mineral? (3) Do you think you are looking at an igneous, metamorphic or sedimentary rock? Go to the chart, and scan the properties. Within each colour group, minerals are arranged in order of increasing refractive index (which more or less corresponds to relief). This should at once limit you to only a few minerals. By looking at the chart, see which properties might help you distinguish between the possibilities. Then, look at the mineral again, and check these further details. Notes: (i) Name: names listed here may be strict mineral names (e.g., andalusite), or group names (e.g., chlorite), or distinctive variety names (e.g., titanian augite). These tables contain a personal selection of some of the more common minerals. Remember that there are nearly 4000 minerals, although 95% of these are rare or very rare. The minerals in here probably make up 95% of medium and coarse-grained rocks in the crust. (ii) IMS: this gives a simple assessment of whether the mineral is common in igneous (I), metamorphic (M) or sedimentary (S) rocks. These are not infallible guides - in particular many igneous and metamorphic minerals can occur occasionally in sediments.
    [Show full text]
  • Crystal Structure Refinement of Lawsonite
    American Mineralogist, Volume 63, pages 3l l-315, 1978 Crystalstructure refinement of lawsonite WnRNTRH. Baun Department of Geological Sciences, Uniuersity o.f Illinois Chicago, Illinois 60680 Abstract 6rAl, Lawsonite,Ca " SirrlO7(OH)r.HrO, is found in low-temperature,high-pressure meta- morphic rocks. It is a hydrous counterpart of anorthite. A specimenfrom the type locality, Tiburon Peninsula,Marin County,California, was used for an X-ray study:a :8.795(3),b: 5.847(l),c : 13.142(6)A,V: 675.3A,Z - 4, Dcat.:3088 g.cm-3,space group Ccmm. Refinementof 865 F"m gave an R : 0.0256.The structure is basedon a three dimensional framework generatedby cross-linkingribbons composedof edgesharing singlechains of Al coordination octahedraand lateral bridging silicategroups The openingsof the framework accommodatethe Ca atomsand the watermolecules. The observedmean distances are Si ' - O : 1.633,Al' O : 1.913and Ca' - O - 2.421A.Thehydrogen atoms parriciprre in bent and bifurcatedhydrogen bonds. Individual cation-anion distances conform well to the exLendedelectrostatic valence rule. Introduction unit cell constantswere refinedfrom the settingof20 The crystal structure of lawsonite, CaAlrSirO, reflectionsmeasured on a singlecrystal X-ray diffrac- (OH)r.HzO, was determinedby Wickman (1947) tometer. The resulting cell constants agree closely in space group C222,. The Si-O bond lengths in with thosereported by Davis and Pabst(1960). Re- the SirO, group as found by Wickman rangedfrom ciprocal space was searchedin a sphere of radius 1.59to 1.72A. Subsequently,the structurewas re- sind/tr : 0.844-'. The total number of measured fined by Rumanova and Skipetrova (1959). They reflectionswas I1,268,which wereaveraged to yield found that it could be describedin the centric space 1,928unique reflections.Of these 1,063had an in- group Ccmm and that the Si-O distanceswere lying tensity of lessthan two sigma, and were not used in in a narrow range:between 1.65 and 1.69A.Recently the refinement.
    [Show full text]
  • Lawsonite Metasomatism and Trace Element Recycling in Subduction Zones A
    Lawsonite metasomatism and trace element recycling in subduction zones A. Vitale Brovarone, Olivier Alard, O. Beyssac, L. Martin, M. Picatto To cite this version: A. Vitale Brovarone, Olivier Alard, O. Beyssac, L. Martin, M. Picatto. Lawsonite metasomatism and trace element recycling in subduction zones. Journal of Metamorphic Geology, Wiley-Blackwell, 2014, 32 (5), pp.489-514. 10.1111/jmg.12074. hal-01107395 HAL Id: hal-01107395 https://hal.archives-ouvertes.fr/hal-01107395 Submitted on 6 Dec 2018 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. Lawsonite metasomatism and trace element recycling in subduction zones A. VITALE BROVARONE,1 O. ALARD,2 O. BEYSSAC,1 L. MARTIN3 AND M. PICATTO4 1Institut de Mineralogie, de Physique des Materiaux, et de Cosmochimie (IMPMC), Sorbonne Universites - UPMC Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, 4 Place Jussieu, F-75005 Paris, France ([email protected]) 2Geosciences Montpellier, Universite Montpellier II, place E. Bataillon, 34095, Montpellier, France 3Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, WA, 6009, Australia 4Dipartimento di Scienze della Terra, Universita degli Studi di Torino, via Valperga Caluso 35, 10100, Torino, Italy ABSTRACT Although lawsonite-bearing rocks are rare in exhumed high-pressure (HP) terranes, they are consid- ered to exert a primary role in subduction dynamics.
    [Show full text]
  • 208-240 My Old Jadeite-Glaucophane
    J. Japan. Assoc. Min. Petr. Econ. Geol. 73, 300-310, 1978. 208-240 M. Y. OLD JADEITE-GLAUCOPHANE SCHISTS IN THE KUROSEGAWA TECTONIC ZONE NEAR KOCHI CITY, SHIKOKU SHIGENORI MARUYAMA Department of Earth Sciences, Faculty of Science, Nagoya University* YOSHIO UEDA Institute of Mineralogy, Petrology and Economic Geology, Tohoku University, Sendai 986 and SHOHEI BANNO Department of Earth Sciences, Faculty of Science, Kanazawa University, Kanazawa 920 A new member of the Kurosegawa tectonic zone was found in the serpentinite near Kochi city. They are high P and low T schists derived from basalt and chert. Three metamorphic events can be deciphered in the high-pressure schists, based upon the texture and mineral paragenesis: first, low P metamorphism at intermediate- to high grade, second, high P and low T metamorphism of the jadeite-glaucophane facies and the thrid, retrograde crystallization of the second stage high P schists within the stability field of lawsonite+pumpellyite+glaucophane. Further, the formation of analcime replacing jadeite took place. The second and third metamorphism can be distinguished on pyroxene mineralogy that j adeite+quartz was stable in the second, but albite+quartz+aegirinej adeite in the third stage of metamorphism. Not all of the high P and low T schists had suffered low P metamorphism before they were metamorphosed by the high P one. Some basaltic rocks directly changed to high P and low T schists. Two muscovites in the schists give K-Ar ages of 208-240 m.y., and a relic igneous biotite, being partly replaced by chlorite, gives 225 m.y. of K-Ar age.
    [Show full text]
  • Pt and Structural Constraints of Lawsonite
    p-T and structural constraints of lawsonite and epidote blueschists from Liberty Creek and Seldovia: Tectonic implications for early stages of subduction along the southern Alaska convergent margin Alicia L6pez-Carmona , Timothy M. Kusky , M. Santosh , Jacobo Abati • Departamento de Petro[ogfa y Geoqufmica and Instituto de Geologfa Economica, Universidad Complutense-Consejo Superior de Investigaciones Cientfficas, 28040 Madrid, Spain b State Key Lab for Geological Processes and Mineral Resources, and Three Gorges [enter for Geohazard, Ministry of Education, China University of Geosciences, Wuhan, 388 Lumo Road, Hongshan District, Wuhan 4300 74, China C Department of Interdisciplinary Science, Faculty afScience, Kochi University, Akebono-cho 2-5-1, Kochi 780 -8520, Japan ABSTRACT The southern Alaska convergent margin contains several small belts of sedimentary and volcanic rocks metamorphosed to blueschist facies, located along the Border Ranges fault on the contact between the Wrangellia and Chugach terranes. These belts are significant in that they are the most inboard, and thus probably contain the oldest record ofTriassic-Jurassic northward-directed subduction beneath Wrangellia The Liberty Creek HP-LT schist belt is the oldest and the innermost section of the Chugach terrane. Within this belt lawsonite blueschists Keywords: contains an initial high-pressure assemblage formed by lawsonite+ phengite+ chlorite + sphene + albite ± Alaska Blueschist apatite ± carbonates and quartz. Epidote blueschists are composed of sodic, sodic -calcic and calcic amphiboles + Subduction epidote + phengite+ chlorite + albite+ sphene± carbonates and quartz. P- T pseudosections computed from Border Ranges Fault four representative samples constrain maximum pressures at 16 kbar and 250-280 QC for the Lawsonite-bearing PT pseudosections blueschists, and 15 kbar and 400-500 QC for the epidote-bearing blueschists, suggesting a initial subduction stage of 50-55 km depth.
    [Show full text]