MICROMORPHOLOGY OF SOILS MICROMORPHOLOGY OF SOILS E.A. FITZPATRICK Department oj Soil Science University oj Aberdeen, UK LONDON NEW YORK CHAPMAN AND HALL First published 1984 by Chapman and Hall Ltd 11 New Fetter Lane, London EC4P 4EE Published in the USA by Chapman and Hall 733 Third Avenue, New York, NY to017 © 1984 E.A. FitzPatrick Softcover reprint of the hardcover 1st edition 1984 ISBN-13: 978-94-010-8946-3 e-ISBN-13: 978-94-009-5544-8 DO I: 10.1007/978-94-009-5544-8 All rights reserved. No part of this book may be reprinted, or reproduced or utilized in any form or by any electronic, mechanical or other means now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the publisher. British Library Cataloguing in Publication Data FitzPatrick, E. A. Micromorphology of soils 1. Soils - Analysis I. Title 631.4'1 S593 Library of Congress Cataloging in Publication Data FitzPatrick, Ewart Adsil. Micromorphology of soils. Bibliography: p. Includes index. 1. Soil micromorphology. I. Title. S593.2.F58 1984 631.4 83-24002 Contents Preface page Xl Acknowledgements Xlll 1 Principles of thin section preparation 1 1.1 Choosing the size of the thin section 1 1.2 Collecting the sample 2 1.3 Removing water from the sample 2 1.4 Impregnating the sample 2 1.5 Lapping the impregnated sample 3 1.6 Polishing the impregnated sample 4 1.7 Grinding, lapping and polishing the 5 slide 2 Preparation ofpolished blocks and thin 6 sections ofsoils 2.1 Collection ofsamples ofsoft coherent 6 non-stony material 2.2 Collection ofsamples of hard material 9 2.3 Collecting loose friable surface 9 samples 2.4 Removal or replacement of water and 10 impregnation with Crystic resin 2.5 Transferring the specimen to the 10 impregnation mould V vi Contents 2.6 Removal of water 13 2.7 Impregnation 15 2.8 Sawing the impregnated block 21 2.9 Surface impregnation with Crystic 22 reSIn 2.10 Lapping the block 23 2.11 Polishing the block 29 2.12 Cleaning the polished block 31 2.13 Mounting the polished block 32 2.14 Labelling the slide 35 2.15 Cutting off the excess specimen 35 2.16 Machine grinding the specimen 35 2.17 Final lapping stages for the specimen 37 2.18 Polishing the specimen 42 2.19 Mounting the cover glass 42 2.20 Logitech machine systems for thin 43 section production 3 Examination ofthin sections and 51 polished blocks 3.1 Examination of thin sections and 51 polished blocks with the stereo- mIcroscope 3.2 Examination of thin sections with the 52 petrological microscope 3.3 The construction and use of the 52 petrological microscope 3.4 Properties of minerals determined 55 with the petrological microscope 4 Properties oflTIinerals in thin sections 66 4.1 Allophane 71 4.2 Amphiboles 71 4.3 Anatase 71 4.4 Antigorite - chrysotile 72 4.5 Apatite 72 4.6 Augite 73 4.7 Biotite 73 4.8 Calcite 75 4.9 Chalcedony 77 4.10 Chlorite 78 4.11 Clinozoisite 78 4.12 Diopside 79 4.13 Enstatite 79 4.14 Epidote 80 4.15 Feldspars 80 4.16 Ferric hydroxide 81 Contents vii 4.17 Garnet 81 4.18 Gibbsite 81 4.19 Goethite 83 4.20 Gypsum 83 4.21 Halite 84 4.22 Halloysite and metahalloysite 84 4.23 Hematite 85 4.24 Hornblende 86 4.25 Hypersthene 86 4.26 Ice 87 4.27 Iddingsite 87 4.28 Ilmenite 88 4.29 Jarosite 89 4.30 Kaolinite 89 4.31 Lepidocrocite 90 4.32 Magnetite 90 4.33 Manganese dioxide 91 4.34 Microcline 91 4.35 Montmorillonite 92 4.36 Muscovite 93 4.37 Olivine 93 4.38 Opal 94 4.39 Orthoclase 95 4.40 Plagioclases 95 4.41 Pyrite 96 4.42 Quartz 97 4.43 Rutile 98 4.44 Serpentine 98 4.45 Siderite 98 4.46 Titanite 99 4.47 Tourmaline 99 4.48 Tremolite - actinolite 99 4.49 Vermiculite 100 4.50 Volcanic glass 101 4.51 Zircon 101 5 Properties applicable to most features 102 seen in thin sections 5.1 Colour 102 5.2 Frequency 103 5.3 Prominence 114 5.4 Size 115 5.5 Shape 116 5.6 Roundness and sphericity 117 5.7 Surface characteristics 118 5.8 Boundaries 118 5.9 Distribution pattern 119 Vll1 Contents 5.10 Relationships with other features 120 5.11 Orientation 121 6 Fabric, structure and matrix 123 6.1 Fabric and structure 124 6.2 Matrix 128 6.3 Conclusions 134 7 Features present in thin sections 136 7.1 Fabric 138 7.2 Structure and pores 140 7.3 Passages - faunal and root 166 7.4 Faecal material 167 7.5 Organic materials 172 7.6 Rock fragments 179 7.7 Detrital grains 183 7.8 Particle size distribution 186 7.9 Fine material 187 7.10 Coatings 207 7.11 Clay plugs 230 7.12 Surface residues 230 7.13 Impregnated surfaces 232 7.14 Anisotropic surfaces - false coatings 233 7.15 Subsurface organizations and 233 accumulations 7.16 Secondary mineral material 234 7.17 Amorphous and microcrystalline 239 material 7.18 Segregations and concretions 239 7.19 Weathering features and products 244 7.20 Microorganisms 249 7.21 Soil crratics 253 7.22 Infillings and intergrowths 253 7.23 Other features 256 7.24 Features observed in polished blocks 256 8 Description ofthin sections and polished 258 blocks 8.1 Homogeneity and heterogeneity 258 8.2 Recognition ofindividuals 259 8.3 Recognition of patterns 260 8.4 n:scription ofindividuals and patterns 261 8.5 Quantification 261 8.6 Interpretation 261 8.7 Description of thin sections 262 8.8 Description of polished blocks 266 8.9 Reminder data of properties 267 Contents ix 8.10 Reminder data offeatures 270 9 Teaching micromorphology 278 9.1 Introductory course in thin section 278 morphology 9.2 Advanced course in thin section 279 morphology 9.3 Exercises 283 10 Photography 286 10.1 Photographing the whole specimen 286 using transmitted light 10.2 Photographing the whole specimen 287 using ultraviolet light 10.3 Photomicrography 287 10.4 Photography for pore identification 288 11 Ancillary techniques 291 11.1 Electron analyses 292 11.2 X-ray analysis of thin sections 294 11.3 Ion thinning 294 11.4 Low temperature ashing 294 11.5 Image analysis 297 11.6 Three-dimensional analysis 297 11.7 Polarization-interference contrast 298 examinations 11.8 Phase contrast 298 11.9 Fluorescence 299 11.10 Staining feldspars 299 11.11 Staining carbonates 302 11.12 Staining clay minerals 306 11.13 Staining microorganisms 306 11.14 Preparation of acetate peels 307 11.15 Removal of iron oxides from thin 308 sections 11.16 Autoradiographs ofimpregnated 311 blocks and thin sections 12 Applications 312 12.1 Agriculture 312 12.2 Archeology 317 12.3 Engineering 319 12.4 Geomorphology 321 12.5 Paleoclimatology 325 12.6 Pedology and paleopedology 325 12.7 Soil microbiology 328 12.8 Soil zoology 329 X Contents 13 The micromorphology of soils 331 APPENDIX 1 Health hazards 358 APPENDIX 2 Defects and faults in thin 360 sections and impregnated blocks APPENDIX 3 Detailed descriptions of 363 thin sections APPENDIX 4 Reminder data of properties 367 APPENDIX 5 Reminder data offeatures 371 Glossary 378 References 414 Index 427 The colour plate section appears between pages 210 and 211. Preface One of the first major studies of weathering and soil formation was made by Harrison (1933) who used thin sections in association with other procedures to study the transformation of minerals in different kinds of rock under the tropical conditions of Guyana. However, Kubiena (1938) is regarded as pioneering thin section studies of soils and during the last two decades there has been a rapid increase in the number of publications devoted almost exclusively to the study of soils in thin sections. In addition to the rather straightforward examinations with the polarizing microscope, thin section techniques are being linked with X-ray diffraction, X-ray microprobe, transmission and scanning electron microscopy, microbiological and other procedures to obtain a fuller insight into the composition and genesis of soils. Thus the study of thin sections of soils is now a major pedological technique for investigating small details in the nature, type and degree of organization of the soil fabric and structure. Thin sections reveal that particles of various sizes and composition react differently to pedological processes and become weathered or organized to form many specific patterns. This book is an attempt to give a comprehensive treatment of thin section studies of soils. Although primarily about the study of thin sections with optical microscopes a few transmission and scanning electron photomicro­ graphs are included to confirm the inferences based upon the studies made with the optical microscope. xi xii Preface This book is intended for honours students, postgraduate students, soil surveyors and similar workers. It is hoped that it will fulfil the following requirements: 1. Easy to be used and understood by students 2. To give information and methods of description for most features seen in thin sections of soils and related materials 3. To relate easily field with thin section data 4. Ultimately to lead to codifying the data for storage and computation Sometimes the value of thin sections studies is questioned. The value and need for thin sections are as follows: 1. To study and analyse the details of the soil fabric 2. To observe and analyse more fully the structure and porosity of the soil both natural and induced 3.