Zonation in Tourmaline from Granitic Pegmatites & the Occurrence of Tetrahedrally Coordinated Aluminum and Boron in Tourmaline
Total Page:16
File Type:pdf, Size:1020Kb
ZONATION IN TOURMALINE FROM GRANITIC PEGMATITES & THE OCCURRENCE OF TETRAHEDRALLY COORDINATED ALUMINUM AND BORON IN TOURMALINE by Aaron J. Lussier A Thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfilment of the requirements of the degree of DOCTOR OF PHILOSOPHY Department of Geological Sciences University of Manitoba Winnipeg Copyright © 2011 by Aaron J. Lussier Library and Archives Bibliothèque et Canada Archives Canada Published Heritage Direction du Branch Patrimoine de l'édition 395 Wellington Street 395, rue Wellington Ottawa ON K1A 0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre référence ISBN: 978-0-494-79264-3 Our file Notre référence ISBN: 978-0-494-79264-3 NOTICE: AVIS: The author has granted a non- L'auteur a accordé une licence non exclusive exclusive license allowing Library and permettant à la Bibliothèque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par télécommunication ou par l'Internet, prêter, telecommunication or on the Internet, distribuer et vendre des thèses partout dans le loan, distrbute and sell theses monde, à des fins commerciales ou autres, sur worldwide, for commercial or non- support microforme, papier, électronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriété du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette thèse. Ni thesis. Neither the thesis nor la thèse ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent être imprimés ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformément à la loi canadienne sur la Privacy Act some supporting forms protection de la vie privée, quelques may have been removed from this formulaires secondaires ont été enlevés de thesis. cette thèse. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. ABSTRACT [1] Four specimens of zoned tourmaline from granitic pegmatites are characterised in detail, each having unusual compositional and/or morphologic features: (1) a crystal from Black Rapids Glacier, Alaska, showing a central pink zone of elbaite mantled by a thin rim of green liddicoatite; (2) a large (~25 cm) slab of Madagascar liddicoatite cut along (001) showing complex patterns of oscillatory zoning; and (3) a wheatsheaf and (4) a mushroom elbaite from Mogok, Myanmar, both showing extensive bifurcation of fibrous crystals originating from a central core crystal, and showing pronounced discontinuous colour zoning. Crystal chemistry and crystal structure of these samples are characterised by SREF, EMPA, and 11B and 27Al MAS NMR and Mössbauer spectroscopies. For each sample, compositional change, as a function of crystal growth, is characterised by EMPA traverses, and the total chemical variation is reduced to a series of linear substitution mechanisms. Of particular interest are substitutions accommodating the variation in [4]B: (1) TB + YAl ↔ TSi + Y(Fe, Mn)2+, where T Y T Y transition metals are present, and (2) B2 + Al ↔ Si2 + Li, where transition metals are absent. Integration of all data sets delineates constraints on melt evolution and crystal growth mechanisms. [2] Uncertainty has surrounded the occurrence of [4]Al and [4]B at the T-site in tourmaline, because B is difficult to quantify by EMPA and Al is typically assigned to the octahedral Y- and Z-sites. Although both [4]Al and [4]B have been shown to occur in natural tourmalines, it is not currently known how common these substituents are. Using 11B and 27Al MAS NMR spectroscopy, the presence of i [4]B and [4]Al is determined in fifty inclusion-free tourmalines of low transition- metal content with compositions corresponding to five different species. Chemical shifts of [4]B and [3]B in 11B spectra, and [4]Al and [6]Al in 27Al spectra, are well-resolved, allowing detection of very small (< ~0.1 apfu) amounts of T-site constituents. Results show that contents of 0.0 < [4]B, [4]Al < 0.5 apfu are common in tourmalines containing low amounts of paramagnetic species, and that all combinations of Si, Al and B occur in natural tourmalines. ii ACKNOWLEDGEMENTS I extend my most sincere gratitude to my advisor, Dr. Frank C. Hawthorne for granting me the opportunity to participate in the research that I have so- enjoyed, and for sharing his enthusiasm and insight into all things mineralogic and crystallographic. I would also like to express my appreciation to the members of my advisory committee: Drs. Norman M. Halden, Scott Kroeker, Elena Sokolova, and Mario Bieringer for their insightful comments over the past years; and to Dr. Lee A. Groat for agreeing to act as external examiner. I am very grateful to the members of the technical, research and support staff in the Department of Geological Sciences: Mr. M. A. Copper, Mr. N. Ball, Dr. Y. Abdu, Dr. P. Yang, Dr. R. Shidu, Mr. R. Chapman, Mr. S. Meijia, Dr. M. Schindler, Ms. D. Danyluk, Ms. Brenda Miller. I am particularly grateful to Mr. M. Cooper and Dr. M. Schindler for the many helpful conversations over the past years, and to Sasha Herwig for assistance with data X-ray data collection. I also thank C. Francis at the Mineralogical Museum at Harvard University for donating the Madagascar liddicoatite. I appreciate the collaborative support received from the MAS NMR lab in the Department of Chemistry at the University of Manitoba: Drs. S. Kroeker, P. M. Aguiar, and V. K. Michaelis. I also wish to thank Drs. R. C. Ewing and J. Zhang at the University of Michigan for access to, and assistance with, the TEM. I acknowledge financial support to me from: (1) the Natural Sciences and Engineering Council of Canada in the form of a PGS-D; (2) the University of Manitoba in the form of a Graduate Fellowship Award; and (3) The Province of Manitoba in the form of Manitoba Graduate Fellowship. I express great thanks to my wife, Kathryn Sexton, my mother, Eileen Lussier, and my father, Mark Lussier for their understanding, support, and patience over the years. iii For Kathy & Mom & Dad iv TABLE OF CONTENTS Abstract ………………………..………………………………………………… i Acknowledgements ………….………………………………………………… iii Dedication …………………….………………………………………………… iv Table of Contents …………….………………………………………………… v List of Tables …………………..………………………………………………… xv List of Figures ………….…….………………………………………………… xvii CHAPTER 1 INTRODUCTION 1.1 Tourmaline: towards a robust petrogenetic tool. …………………… 1 1.2 General formula and crystal structure ……………………………… 2 1.2.1 Space-group symmetry …………………………………….. 6 1.3 Tourmaline nomenclature and classification ……………………… 6 1.3.1 Tourmaline groups …………………………….…………… 7 1.3.2 Tourmaline species …………………………….…………… 9 1.3.3 Tourmaline classification …………………………………… 9 1.4 Selected physical properties of tourmaline ……………………… 16 1.4.1 Crystal form and habit …………………………………… 16 1.5 Selected optical properties of tourmaline ………………………… 17 1.5.1 Colour and colour zoning …………………..…………… 18 1.5.2 Important causes of colour …………………………… 19 v 1.6 Solid solutions in tourmaline ………………………………………… 20 1.7 Contribution of this work …………………………………………… 20 1.7.1 Review of tourmaline crystal chemistry ……………………. 20 1.7.2 Crystal chemistry of the T-site ……………………………… 21 1.7.3 Compositional zoning in tourmalines from granitic pegmatites …………………………….…………… 22 1.7.4 Note about publications ……………………………………… 23 CHAPTER 2 CRYSTAL CHEMISTRY OF CRYSTAL STRUCTURE 2.1 Introduction ………………………………….……………………… 24 2.2 Site populations and polyhedron geometry ……………………..… 25 2.2.1 The Z-site ………………………..………………………..… 26 2.2.1.1 Variation in <Y,Z-Φ> .......................………………… 29 2.2.1.2 Variation in <Z-Φ> …...................................………… 30 2.2.2 The Y-site ………………………………………………………. 34 2.2.2.1 Variation in <Y-Φ> …................................................… 35 2.2.2.2 Cation disorder between Y- and Z-octahedra ………… 40 2.2.2.3 Y-site vacancies ……………………………………….… 43 2.2.3 The T-site …………………………………………………….… 44 2.2.3.1 Variation in <T-O> …………….................................… 45 2.2.3.2. Fe3+ and the T-site …………………………………….. 47 2.2.4 The X-site ……………………………………………………..… 48 vi 2.2.4.1 Variation in <X-O> …………………………..…………… 48 2.2.5 The B-site …………………………………………………… 51 2.2.6 The O(1)-site ………………………………………..………... 51 2.2.6.1 The occurrence of F at O(1) ………………………….… 52 2.2.7 The O(3)-site ………………………………….………………… 53 2.3 Implications of short-range order around the O(1)-site ..………… 53 2.3.1 Bond-valence requirements at the O(1) site ………………………………………………..… 54 2.3.2 The stability of short-range clusters ………..……………… 54 2.3.1 O2- at the W-site: a cause of Y-Z disorder in tourmaline ………………………………………… 55 2.4 Short-range order around the O(3)-site ……………………… 56 CHAPTER 3 PHYSICAL DESCRIPTION OF TOURMALINE SAMPLES OF THIS WORK 3.1 Introduction ……………………………………………………………… 58 3.2 Oscillatory zoned liddicoatite from the Anjanabonoina Pegmatite, Madagascar …………………………………………………………… 58 3.2.1 Sample description ………………………………..………..… 58 3.2.2 Provenance ……………………………………….…………… 62 3.3 Mushroom and wheatsheaf tourmalines from Mogok, Myanmar ……………………………………………….. 63 3.3.1 Mushroom tourmaline: sample description ……..…………