Table of contents for Rock coatings / by Ronald I. Dorn.


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Section 1. General Perspectives ............................ 1
Chapter 1. Introduction ..................................    2
1.1. Focus and Organization of Book ............................. 2
1.2. Awareness of Rock Coatings ............................... 4
1.3. Nomenclature  ......................................... 11
1.4. Historical Perspective on Major Research Threads .................  16
Chapter 2. Paradigms and Methods in Rock Coating Research... 19
2.1. Alternative Perspectives ................................... 19
2.2. Adopting the Paradigm of Landscape Geochemistry ................... 20
2.2.1. Adjudicating Competing Hypotheses ......................... 20
2.2.2. Introduction to Landscape Geochemistry ..................... 20
2.2.2.1. The Development of Landscape Geochemistry in Soviet
Geography  ...............................         20
2.2.2.2 Landscape Geochemistry Outside of Russia/Soviet Union ....... 21
2.2.2.3. Fundaments of Landscape Geochemistry .................. 22
2.2.3. Rock Coatings as a Part of the Geochemical Landscape ........... 24
2.3. Methods Used in Original Data Gathering ....................... 27
2.3.1. Field Collection ..................................... 27
2.3.2. Preparation of Polished Cross-sections and Ultrathin Sections ....... 29
2.3.3. Secondary Electron Microscopy ........................... 29
2.3.4. Backscattered Electron Microscopy  ....................... 30
2.3.5. X-Ray Spectrometry .......... .. ......... ............  30
2.3.5.1. X-Ray Images ....................................... 31
2.3.5.2. Energy Dispersive Spectrometry ....................... 31
2.3.5.3. Wavelength Dispersive Spectrometry  ..........   31
2.3.5.4. Detection of Organic Matter .......... ..........  31
2.3.6. Admission of Bias ............................. 32



Section 2. Different Rock Coatings .......................... 33
Chapter 3. Anthropogenic Pigments .........................34
3.1. Introduction  ...........................................  34
3.2. Prehistoric Rock Pigments .................................  34
3.3. Historic Rock Painting ...................................  36
3.3.1. Coatings to Change Appearances .......................... 36
3.3.2. Coatings to Preserve Stone ..............................  38
3.3.3. Coatings to Preserve Landscape Aesthetics .................... 38
Chapter 4. Lithobiontic Coatings .......................... 41
4.1. Introduction  ...........................................  41
4.2. Different Types of Lithobiontic Coatings.......................  43
4.2.1. Bacteria  ...........................................  43
4.2.2. Cyanobacteria  ......................................  48
4.2.3. Fungi ............................................  49
4.2.4. Algae  ............................................  56
4.2.5. Lichens  ...........................................  57
4.2.6. Higher Plants ................................  ....   60
4.3. Controls on  Distributions .................................. 61
4.4. Impact of Lithobiontic Coatings .............................  63
4.4.1. On Organic Remains ..................................  63
4.4.2. On Rock Weathering  ..................................  64
4.4.3. On Other Rock Coatings ............................ .. 65
Chapter 5. Carbonate Crusts .........   ................  67
5.1. Introduction ........................................... 67
5.2. Freshwater Deposits ...................................... 67
5.3. Marine Littoral .........................................  70
5.4. Pedogenic  ............................................  72
5.5. Subaerial Rock Faces ..................................... 79
5.6. Carbonate Crusts and Greenhouse Warming ...................... 83
Chapter 6. Case Hardening Agents ......................... 85
6.1. Introduction  .........................................   85
6.2. Characteristics .................... ....................  86
6.2.1. Environmental Settings ..............................  86
6.2.1.1. Subaerial Desert Exposures ....................... .. 86
6.2.1.2. Subsurface Origins ................................  87
6.2.1.3. Associated with Carved Rock ......................... 88
6.2.1.4. Tropics  ........................................  91
6.2.1.5   Temperate Environments .....;......... .......... ...  94



6.2.1.6. Arctic and Alpine Environments ....... ................ 95
6.2.2. Composition .............. . ....................  96
6.2.2.1. Material Added to Weathering Rind ...... ............... 96
6.2.2.2. Rock Coatings as Case Hardening Agents ................. 101
6.2.2.3. Fused Rock as a Case Hardening Agent ................... 104
6.2.3. Rates of Formation ................................... 105
6.3. Origin ..............................................  106
Chapter   7.   Dust   Films ...................................  108
7.1. Introduction ...........................................  108
7.2. Characteristics  ... .....................................  108
7.2.1. Environmental Settings .................................. 108
7.2.2. Composition  ... ....................................  112
7.2.3. Rates of Formation ...................................  115
7.3. Origin ...................................................  117
Chapter   8. Heavy   Metal  Skins .............................  120
8.1. Introduction  ...........................................  120
8.2. Manganese Skins .......................................  120
8.2.1. Environmental Settings ................................  121
8.2.2. Composition .......................................  122
8.2.2.1. Mineralogy .....................................  122
8.2.2.2. Chemistry ...................  ............... 122
8.2.2.3. Scavenging of Other Heavy Metals ..................... 130
8.2.2.4. Rates of Formation ................................ 130
8.2.2.5. Morphology  ................ ...................  130
8.2.3. Origin  ..............................     ...... 132
8.2.3.1. Biotic Hypotheses ................................. 132
8.2.3.2. Abiotic Hypotheses   ................................ 134
8.2.3.3. Combination of Biotic and Abiotic Formation .............. 134
8.3. Heavy metal skins as a mix of natural and anthropogenic factors ....... 135
8.3.1. Introduction ....................................... 135
8.3.2. Lead-enriched Heavy Metal Skins ..........................  136
8.3.3. Copper and Other Heavy Metal Skins ............... .............  138
8.3.4. Patina, Metal Corrosion and Rock Coatings ................... 141
Chapter   9.  Iron   Films ....................................  144
9.1. Introduction .......................................... 144
9.2. Characteristics .................... .....................  146
9.2.1. Environmental Settings ................................  146
9.2.1.1. Artifacts ................... ........... .......  146
9.2.1.2. Fractures in Rocks  ...............................  147
9.2.1.3. Grain Coating on Sand ....... ................  151
9.2.1.4. Springs .....................................  153
9.2.1.5. Streams .... ................................  153
9.2.1.6. Subaerial Rock  Surfaces ............................. 155
9.2.1.7. Underside of Rocks ............................. 159



9.2.1.8. Iron Films Interdigitated With Other Rock Coatings .......... 160
9.2.2. Composition ............... .......................  163
9.2.2.1. Mineralogy ....... . ................ ...........  164
9.2.2.2. Type I Iron Films ................................. 164
9.2.2.3. Type II Iron Films ................................ 169
9.2.2.4. Type III Iron Films ................................  171
9.2.2.5 Heavy Metal Scavenging ........................... 178
9.2.3. Information on Rates of Formation  ......................... 178
9.3. Origin  ...........................                   180
9.3.1. Source of the Iron  ....................................  180
9.3.2. Abiotic Genesis ................................... ..  181
9.3.3. Biotic Genesis  ......................................  182
9.3.4. General Models ............................ ....  184
Chapter 10. Manganiferous Rock Varnish .................... 186
10.1. Introduction  ..................................... 186
10.2. Characteristics ................................ ..... 188
10.2.1. Environmental Settings: Desert Varnish or Rock Varnish? ......... 188
10.2.1.1. Perspectives Prior to World War II .....................  188
10.2.1.2. Perspectives in the Middle Years ...................... 189
10.2.1.3. Notion of an Ideal Climate of Formation ................ 189
10.2.1.4. Environmental Context ............................ 191
10.2.2. Physical-Chemical Characteristics ......................... 193
10.2.2.1. Thickness ..................................... 193
10.2.2.2. Color ........................................  193
10.2.2.3. Sheen .................................. .. 194
10.2.2.4. Mineralogy ........... .........................  195
10.2.2.5. Chemistry  .................... ............ 198
10.2.2.6. Micromorphology ......... ................ ......... 206
10.2.2.7. Textures Seen in Cross-Section  ....................... 209
10.2.2.8. Post-Depositional Modification ...................... 212
10.2.3. Classification of Rock Varnish ..........................  214
10.2.3.1. Prior Perspectives on Classification .................... 214
10.2.3.2. Why Classify Rock Varnish? ........................ 215
10.2.3.3. Color/Chemistry Differences ......................... 216
10.2.3.4. Geomorphic Differences ............................ 216
10.2.3.5. Microscopic Distinctions  ........................... 217
10.2.3.6. Dangers of Misidentification ......................... 218
10.2.3.7. Dangers of Instituting a Bad Classification ................ 221
10.2.3.8. A Tiered Classification for Rock Varnish ................. .... 222
10.2.4. Rates of Formation  ..................................  224
10.2.4.1. Observations Prior to World War II .................... 224
10.2.4.2. Observations from World War II to the First Dissertation ...... 225
10.2.4.3. Calculating Rates of Formation ......................... 227
10.3. Origin ..............................................  231
10.3.1. Framing the Issues Historically ........ .................. 231
10.3.1. Debate Prior to World War II .......................... 231
10.3.1.1. Internal Origin ............................. . 231



10.3.1.2. External Origin  ...............................  233
10.3.1.3. Biological Origin  ..............................  234
10.3.1.4. Polygenetic Origin .............................  235
10.3.2. Debate from World War II to the First Dissertation ........... 236
10.3.2.1. Internal Origin  ................................ 236
10.3.2.2. External Origin  ............................. .  237
10.3.2.3. Both Internal and External....................... 237
10.3.2.4. Manganese Enhancement by Chemical Processes........ 237
10.3.2.5. Manganese Enhancement by Biotic Processes ........... 237
10.3.2. Source of the Manganese .........................  239
10.3.3. New Polygenetic Model of Varnish Formation ................ 241
10.3.2.1. Clay Minerals at the Building Block Level............. 241
10.3.2.2. Manganese Enhancement......................... 242
10.3.2.3. How Rock Varnish Grows  .................... 246
Chapter 11. Nitrates and Other Uncommon Rock Coatings ...... 248
11.1. Introduction  .........................................  248
11.2. Phosphate  Skins  ..................................... . 248
11.3. Nitrate  Crusts  .........................................  254
11.4. Salt Crusts  ...........................................  256
11.5. Sulphate  Crusts  ...............................262
11.6 Why these Rock Coatings have a Limited Distribution .............. 266
Chapter  12.  Oxalate-rich  Crusts ............................ 268
12.1. Introduction  ..........................................  268
12.2. Characteristics  .........................................269
12.2.1. Environmental Settings ................................269
12.2.2. Composition   ......................................  270
12.2.3. Rates of Formation  ..................................  272
12.3. Origin  ..............................................  275



13.2.1.11. Silica Glazes Interdigitated With Other Rock Coatinf
13.2.2. Composition ...............................
13.2.2.1 Type I. Homogeneous Amorphous Silica Glaze .....
13.2.2.2. Type II. Detrital-rich Silica Glaze ..............
13.2.2.3. Type III. Alumina-Iron-rich Silica Glaze ..........
13.2.2.4. Type IV. Alumina-rich Silica Glaze .............
13.2.2.5. Type V. Iron-rich Silica Glaze ................
13.2.2.6. Type VI. Alumina Glaze ....................
13.2.3. Rates of Formation ...........................
13.3. Origin  .....................................
13.3.1. Source of the Silica ...........................
13.3.2. Abiotic Genesis .............................
13.3.3. Biotic Genesis ..............................
13.3.4. General Models  .............................
13.4. Speculation on Iron Films on Mars ...................
Section 3. Synthesis ..............................
Chapter 14. General Model of Rock Coating Developmer
14.1 Introduction ..................................
14.2 Landscape Geochemical Hierarchy of Controls ...........
14.2.1. First-Order Processes: Geomorphic Controls ..........
14.2.1.1. Exposure of Bare Rock .....................
14.2.1.2. Stability of Rock Surfaces ...................
14.2.1.3. The Role of Rock Type ....................
14.2.2. Second-Order Processes: Inheritance from a Subsurface Pos
14.2.3. Third-Order Processes: Habitability for Lithobionts .....
14.2.4. Fourth-Order Processes: Transport Pathways ............
14.2.5. Fifth-Order Processes: Biogeochemical Barriers ........
14.2.6. A consideration for the dynamic ..................
14.3. The Hierarchical Model as an Interpretive Tool ...........
Chapter 15. Analyzing Geographical Variations in Rock
15.1 Introduction ...................................
15.2. Different Approaches to Map Regional Geographical Variabilit
15.2.1 Generalization of Micron-Scale Analyses ............
15.2.2 Generalization of Field Observations ...............
15.2.3 Remotely Sensed Imagery ......................



15.3.4.2. Role of Rock Coatings in the Weathering System .....
15.3.4.2.1. Iron Films ...........................
15.3.4.2.2. Silica Glaze ..........................
15.3.4.2.3. Dust Films ...........................
15.3.4.2.4. Carbonate and Sulfate Crusts ............
15.3.4.2.5. Oxalate-Rich Crusts ......... .......
15.3.4.2.7. Phosphate Skins .......................
15.3.4.2.8. Rock  Varnish  .........................
15.3.4.3. Comparison with Rock Coatings in Other Geographic Se
15.3.4.4. Implications for Understanding Geographical Variations ii
Rock  Coatings  ..................................
15.4. Concluding Perspectives ............................
References ..............................
Geographical  Index .................................
Subject   Index  .....................................








Library of Congress subject headings for this publication: Rocks Surfaces, Coatings, Geochemistry