Principles of Stable Isotope Geochemistry

Reihe
Prentice Hall
Autor
Zachary Sharp
Verlag
Pearson
Einband
Hardcover
Auflage
1
Sprache
Englisch
Seiten
360
Erschienen
März 2006
ISBN13
9780130091390
ISBN
0130091391
Related Titles


Produktdetail

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Description

For courses in Geochemistry that emphasize stable isotopes, offered in departments of Geology.

 

Discussion of stable isotope geochemistry is generally limited to a specific scholarly paper or to cursory coverage in a larger geochemistry text. This is the first dedicated text to cover the basics of a wide range of stable isotope applications in a manner appropriate for someone entering the field. At the same time, it offers sufficient detail - and numerous references and examples - to direct research for further inquiry.

Features

Functional, practical organization:

- Each chapter covers a specific topic of stable isotope geochemistry.

- Each chapter can be used as a weekly lesson.

 

Discussion of diverse topics such as hydrology, carbon in plants, meteorites, carbonates, metamorphic rocks, etc.

 

Extensive discussion of theory and principles of isotope fractionation.

 

Unique, up-to-date discussion of meteorite (extraterrestrial) isotope data.

 

Historical perspective - Presents the subject in an interesting context, with the classic papers noted.

 

Problems with answers at the end of each chapter.

 

Well-captioned figures illustrating important concepts.

 

Extensive bibliography (over 750 references cited).

 

Table of Contents

PREFACE xi

 

ABOUT THE AUTHOR xiii

 

1 INTRODUCTION 1

1.1 Historical Background 1

1.2 Scope of the Discipline 4

1.2.1 What Are Stable Isotopes? 5

1.2.2 Which Elements and Why? 7

1.3 Abundances of the Rare Isotopes of Light Elements 7

1.4 Characteristics of Elements That Undergo Significant Isotopic Fractionation 7

1.5 Applications in the Earth Sciences 9

1.6 Isotope Effects 10

1.6.1 Kinetic Isotope Effects 10

1.6.2 Equilibrium Isotope Effects 11

References 13

 

2 TERMINOLOGY, STANDARDS, AND MASS SPECTROMETRY 15

2.1 Overview 15

2.2 Isotopologues, Isotopomers, and Mass Isotopomers 15

2.3 The Delta Value 17

2.4 Isotope Exchange Reactions 20

2.5 The Fractionation Factor 21

2.6 103 ln α, Δ, and the ε Value 22

2.7 Reference Standards 24

2.7.1 Hydrogen 25

2.7.2 Carbon 28

2.7.3 Nitrogen 28

2.7.4 Oxygen 29

2.7.5 Sulfur 30

2.8 Isotope Ratio Mass Spectrometry 30

2.8.1 The First Isotope Ratio Mass Spectrometers 30

2.8.2 Modern Conventional Mass Spectrometers 31

2.8.3 Gas Chromatograph Isotope Ratio Mass Spectrometry (GC-IRMS) 33

2.8.4 Gases Measured in Isotope Ratio Mass Spectrometry 33

2.8.5 Relations between Measured and Desired Isotopic Ratios 35

2.8.6 Ion Microprobe Analyses of Stable Isotope Ratios 36

References 39

 

3 EQUILIBRIUM ISOTOPIC FRACTIONATION 40

3.1 Introduction 40

3.2 Theoretical Determination of Stable Isotope Fractionation Factors 41

3.2.1 Free Energy of Reaction 41

3.2.2 The Internal Energy of a Molecule 42

3.2.3 Vibrational Partition Function 43

3.2.4 Translational and Rotational Partition Function 45

3.2.5 The Complete Partition Function Ratio 46

3.2.6 Extension to More Complex Molecules 46

3.2.7 Relationship to Temperature 46

3.2.8 “Empirical” Theoretical Methods 47

3.3 Experimental Determination of Fractionation Factors 47

3.3.1 Introduction 47

3.3.2 Mineral—Water Exchange Reactions 49

3.3.3 Mineral—Calcite Exchange Reactions 51

3.3.4 Mineral—CO2 Exchange Reactions 51

3.3.5 The Three-Phase Approach 52

3.4 Empirical Determination of Fractionation Factors 52

3.5 Other Potential Factors Controlling Isotope Partitioning 53

3.5.1 Pressure Effect 53

3.5.2 Composition and Structure 54

3.6 So Which Fractionation Factors Are Correct? 56

3.6.1 An Example from Quartz—Calcite Fractionation 56

References 60

 

4 THE HYDROSPHERE 64

4.1 Overview 64

4.2 Natural Abundances of the Isotopologues of Water 65

4.3 Meteoric Water 67

4.4 The Meteoric Water Line 68

4.4.1 General Features of the GMWL 69

4.4.2 Variations in Slopes and Intercepts of Local MWLs 69

4.4.3 Meteoric Waters in Arid and Semiarid Environments 70

4.5 The Deuterium Excess Parameter 71

4.6 Evaporation and Condensation 74

4.6.1 Evaporation 74

4.6.2 Condensation: Closed-System (Batch) Isotopic Fractionation 75

4.6.3 Condensation: Open-System (Rayleigh) Isotopic Fractionation 78

4.7 Factors Controlling the Isotopic Composition of Precipitation 80

4.7.1 Temperature 80

4.7.2 Distance or Continentality Effect 82

4.7.3 Latitude Effect 83

4.7.4 Altitude Effect 83

4.7.5 Amount Effect 84

4.7.6 Seasonal Effects 86

4.8 Groundwater 86

4.9 Geothermal Systems 88

4.10 Basinal Brines and Formation Waters 89

4.11 Glacial Ice 91

4.11.1 Underlying Bases for Glacial Paleoclimatology 92

4.11.2 Determining the Age of Glacial Ice 93

4.11.3 Thinning of Ice Layers 94

4.11.4 The Example of Camp Century, North Greenland 94

4.11.5 Example of the GRIP Summit Core: Flickering Climates 97

References 100

 

5 THE OCEANS 103

5.1 Overview 103

5.2 Oxygen Isotope Variations in Modern Oceans 104

5.2.1 Salinity—δ18O Relations in Shallow Marine Waters 104

5.2.2 Salinity—δ18O Relations in Deep Ocean Waters 105

5.3 Depth Profiles in Modern Oceans: δ18O(O2)aq. and δ13C(ΣCO2) 108

5.4 Isotopic Compositions of Ancient Oceans 109

5.4.1 Primitive Oceans 109

5.4.2 Secular Changes in δ18O of Marine Sediments 111

5.5 Seawater—Basalt Interactions: Buffering the δ18O Value of the Ocean 112

5.5.1 Low-Temperature Alteration 112

5.5.2 High-Temperature Alteration 113

5.5.3 Evidence from Drill Core Material 114

5.5.4 Evidence from Obducted Material 114

5.6 Buffering the 18O/16O Ratio of Ocean Water 116

5.6.1 Summing the Processes Affecting the 18O/16O Ratio of Seawater 116

5.6.2 Model Calculations 116

5.6.3 Unresolved Controversy 117

References 118

 

6 BIOGENIC CARBONATES: OXYGEN 120

6.1 Introduction 120

6.2 The Phosphoric Acid Method 121

6.2.1 A Major Breakthrough 121

6.2.2 Acid Fractionation Factors 123

6.2.3 Applicability 124

6.3 The Oxygen Isotope Paleotemperature Scale 125

6.4 Factors Affecting Oxygen Isotope Paleotemperatures 129

6.4.1 Variations in δ18O of Ocean Water in Space and Time 130

6.4.2 Vital Effects 131

6.4.3 Diagenesis 133

6.4.4 Ecology of the Organism 138

6.5 Applications of Oxygen Isotope Paleothermometry 139

6.5.1 The Quaternary 139

6.5.2 The Paleogene and Neogene (Cenozoic) 140

6.5.3 Older Samples 140

6.6 Application to Continental Carbonates 141

References 145

 

7 CARBON IN THE LOW-TEMPERATURE ENVIRONMENT 149

7.1 Introduction 149

7.2 The Carbon Cycle 150

7.2.1 Carbon Isotope Budget of the Earth 153

7.3 Carbon Reservoirs 153

7.3.1 Mantle 153

7.3.2 Plants 153

7.3.3 Organic Carbon in Sediments 157

7.3.4 Methane 159

7.3.5 Atmospheric CO2 160

7.4 δ13C Values of Carbonates 161

7.4.1 Introduction 161

7.4.2 General Characterization of Carbonates 162

7.4.3 The Vital Effect 162

7.4.4 Carbonate Speciation Effects 165

7.4.5 Controls on the δ13C Value of Marine Carbonates over Long Timescales 165

7.4.6 Variations in the δ13C Value of Marine Carbonates at Short Timescales 169

7.5 δ13C Studies of Terrestrial Carbonates 171

References 174

 

8 LOW-TEMPERATURE MINERALS, EXCLUSIVE OF CARBONATES 179

8.1 Introduction 179

8.2 Phosphates 179

8.2.1 Analytical Techniques 180

8.2.2 Applications to Marine Paleothermometry 181

8.2.3 Application to Mammals: Theory 183

8.2.4 Sample Applications 186

8.3 Cherts 189

8.3.1 Application to Precambrian Chert Deposits 189

8.3.2 Application to Phanerozoic Cherts 190

8.3.3 Diagenesis 191

8.3.4 Application to Recent Sediments 193

8.3.5 Other Silica Applications 194

8.4 Clay Minerals 195

8.4.1 Early “Bulk” Sample Studies 195

8.4.2 Grain-Size Considerations 196

8.5 Iron Oxides 199

References 201

 

9 NITROGEN 206

9.1 Introduction 206

9.2 The Nitrogen Cycle 207

9.3 Nitrogen Isotope Fractionation 208

9.3.1 Nitrogen Fixation 209

9.3.2 Mineralization 209

9.3.3 Assimilation 210

9.3.4 Nitrification 210

9.3.5 Denitrification 210

9.4 The Characteristic δ15N Values of Various Materials 211

9.4.1 Plants and Soil 212

9.4.2 Other Terrestrial Reservoirs 212

9.4.3 Nitrogen in the Oceans 213

9.5 Nitrogen Isotope Ratios in Animals 216

References 219

 

10 SULFUR 222

10.1 Introduction 222

10.2 Analytical Techniques 223

10.3 Equilibrium Fractionations and Geothermometry 225

10.4 Sulfate and Sulfide Formation at Low Temperatures: The Sedimentary Sulfur Cycle 228

10.5 Secular Variations in Sulfur 231

10.5.1 Long-Term Variations 231

10.5.2 Alternative Approaches: Barite and Trace Carbonates 232

10.5.3 Time Boundaries 233

10.5.4 Archean Sulfates: Clues to the Early Atmosphere 234

10.5.5 Sulfur Isotope Anomalies: Mass-Independent Fractionation 235

10.6 Sulfur Isotope Ratios in the Terrestrial Environment 238

10.7 Oxygen Isotope Variations in Sulfates 236

References 239

 

11 IGNEOUS PETROLOGY 242

11.1 Introduction 242

11.2 The Mantle 243

11.2.1 Oxygen 243

11.2.2 Carbon 247

11.2.3 Nitrogen 251

11.2.4 Hydrogen 252

11.2.5 Sulfur 254

11.3 Emplacement of Plutonic Rocks: Interactions with the Crust and Hydrosphere 255

11.3.1 Normal Igneous Rocks 256

11.3.2 Shallow-Level Hydrothermal Alteration by Meteoric Water: Low Plutonic Rocks 256

11.3.3 High—δ18O Igneous Rocks 258

11.4 Calculating Fluid/Rock Ratios 259

11.5 Other Processes: Degassing, Assimilation, and Fractional Crystallization 261

11.5.1 Magmatic Volatiles 261

11.5.2 Assimilation—Fractional Crystallization (AFC) Processes 263

References 266

 

12 METAMORPHIC GEOLOGY 272

12.1 Introduction 272

12.2 Stable Isotopes as Geochemical Tracers 273

12.2.1 Closed System: Protolith Identification and Alteration 273

12.2.2 Open Systems: Volatilization and Fluid Infiltration Processes 274

12.3 Fluid Sources and Fluid—Rock Interaction 280

12.3.1 Oxygen and Hydrogen 280

12.3.2 Carbon 282

12.3.3 Sulfur 283

12.4 Scales of Equilibration During Metamorphism 284

12.4.1 Regional-Scale Exchange 284

12.4.2 Localized Exchange 285

12.5 Quantifying Fluid—Rock Ratios and Fluid Fluxes 286

12.5.1 Simple Mixing Models: Zero-Dimensional Water—Rock Interaction Models 286

12.5.2 One-Dimensional (Directional) Water—Rock Interaction Models 287

12.6 Thermometry 291

12.6.1 Introduction 291

12.6.2 Oxygen Isotope Thermometry in Metamorphic Rocks: Testing for

Equilibrium 293

12.6.3 Applications of Stable Isotope Thermometry 295

12.7 Retrograde Exchange: “Geospeedometry” 296

12.8 State of the Art 300

References 302

 

13 EXTRATERRESTRIAL MATERIALS 309

13.1 Introduction 309

13.2 Classification of Meteorites 310

13.3 Oxygen Isotope Variations in Meteorites 310

13.3.1 Introduction 310

13.3.2 Discovery of an 17O Anomaly 312

13.3.3 Possible Explanations: Mixing of Two Distinct Reservoirs 313

13.3.4 Mass-Independent Fractionation 316

13.4 Hydrogen 318

13.4.1 Introduction 318

13.4.2 Meteorites 319

13.5 Carbon 320

13.6 Nitrogen 322

References 325

 

APPENDIX A Standard Reference Materials for Stable Isotopes 329

 

APPENDIX B Sample Calculation of the Correction Procedure for Adjusting

Measured Isotope Data to Accepted IAEA Reference Scales 332

 

INDEX 334