Isotopes: Principles and Applications, 3rd Edition

Preface xxv

Part I Principles of Atomic Physics 1

1 Nuclear Systematics 3

1.1 Discovery of Radioactivity 3

1.2 Internal Structure of Atoms 4

1.3 Origin of the Elements 12

1.4 Summary 14

References 14

2 Decay Modes of Radionuclides 15

2.1 Beta-Decay 15

2.2 Alpha-Decay 24

2.3 Spontaneous and Induced Fission 28

2.4 Summary 33

References 33

3 Radioactive Decay 34

3.1 Law of Radioactivity 34

3.2 Radiation Detectors 37

3.3 Growth of Radioactive Daughters 39

3.4 Units of Radioactivity and Dosage 42

3.5 Medical Effects of Ionizing Radiation 43

3.6 Sources of Environmental Radioactivity 46

3.7 Nuclear Reactions 47

3.8 Neutron Activation Analysis 47

3.9 Summary 53

References 53

4 Geochronometry 55

4.1 Growth of Radiogenic Daughters 55

4.2 Assumptions for Dating 57

4.3 Fitting of Isochrons 60

4.4 Mass Spectrometry and Isotope Dilution 64

4.5 Summary 71

References 71

Part II Radiogenic Isotope Geochronometers 73

5 The Rb–Sr Method 75

5.1 Geochemistry of Rb and Sr 75

5.2 Principles of Dating 76

5.3 Rb–Sr Isochrons 80

5.4 Dating Metamorphic Rocks 89

5.5 Dating Sedimentary Rocks 95

5.6 Summary 106

References 107

6 The K–Ar Method 113

6.1 Principles and Methodology 113

6.2 Retention of ⁴⁰Ar by Minerals 115

6.3 K–Ar Isochrons 120

6.4 Volcanic Rocks of Tertiary Age 121

6.5 Dating Sedimentary Rocks 126

6.6 Metamorphic Veil 132

6.7 Precambrian Timescales 134

6.8 Summary 138

References 138

7 The ⁴⁰Ar*/ ³⁹Ar Method 144

7.1 Principles and Methodology 144

7.2 Incremental Heating Technique 147

7.3 Excess ⁴⁰Ar 151

7.4 Argon Isotope Correlation Diagram 153

7.5 Laser Ablation 157

7.6 Sedimentary Rocks 159

7.7 Metasedimentary Rocks 162

7.8 Metamorphic Rocks: Broken Hill, N.S.W., Australia 166

7.9 Thermochronometry: Haliburton Highlands, Ontario, Canada 1

7.10 Summary 171

References 172

8 The K–Ca Method 180

8.1 Principles and Methodology 180

8.2 Isotope Geochemistry of Calcium 183

8.3 Summary 190

References 191

9 The Sm–Nd Method 194

9.1 Geochemistry of Sm and Nd 194

9.2 Principles and Methodology 197

9.3 Dating by the Sm–Nd Method 202

9.4 Meteorites and Martian Rocks 207

9.5 Lunar Rocks 209

9.6 Summary 211

References 211

10 The U–Pb, Th–Pb, and Pb–Pb Methods 214

10.1 Geochemistry of U and Th 214

10.2 Decay of U and Th Isotopes 215

10.3 Principles and Methodology 218

10.4 U,Th–Pb Dates, Boulder Creek Batholith, Colorado 221

10.5 Wetherill’s Concordia 223

10.6 Alternative Pb Loss Models 227

10.7 Refinements in Analytical Methods 230

10.8 Dating Detrital Zircon Grains 233

10.9 Tera–Wasserburg Concordia 236

10.10 U–Pb, Th–Pb, and Pb–Pb Isochrons (Granite Mountains, Wyoming) 240

10.11 Pb–Pb Dating of Carbonate Rocks 242

10.12 U–Pb and Th–Pb Isochrons of Carbonate Rocks 245

10.13 Summary 249

References 250

11 The Common-Lead Method 256

11.1 The Holmes–Houtermans Model 256

11.2 Dating Common Lead 261

11.3 Dating K-Feldspar 268

11.4 Anomalous Leads in Galena 270

11.5 Lead–Zinc Deposits, Southeastern Missouri 274

11.6 Multistage Leads 279

11.7 Summary 280

References 281

12 The Lu–Hf Method 284

12.1 Geochemistry of Lu and Hf 284

12.2 Principles and Methodology 286

12.3 CHUR and Epsilon 288

12.4 Model Hf Dates Derived from CHUR 289

12.5 Applications of Lu–Hf Dating 290

12.6 Summary 294

References 294

13 The Re–Os Method 297

13.1 Rhenium and Osmium in Terrestrial and Extraterrestrial Rocks 297

13.2 Principles and Methodology 301

13.3 Molybdenite and ¹⁸⁷Re–¹⁸⁷Os Isochrons 302

13.4 Meteorites and CHUR-Os 305

13.5 The Cu–Ni Sulfide Ores, Noril’sk, Siberia 310

13.6 Origin of Other Sulfide Ore Deposits 312

13.7 Metallic PGE Minerals 313

13.8 Gold Deposits of the Witwatersrand, South Africa 314

13.9 The Pt–Os Method 316

13.10 Summary 317

References 317

14 The La–Ce Method 322

14.1 Geochemistry of La and Ce 323

14.2 Principles and Methodology 324

14.3 La–Ce Isochrons 327

14.4 Meteorites and CHUR-Ce 329

14.5 Volcanic Rocks 331

14.6 Cerium in the Oceans 332

14.7 Summary 337

References 338

15 The La–Ba Method 340

15.1 Geochemistry of La and Ba 340

15.2 Principles and Methodology 341

15.3 Amitsoq Gneiss, West Greenland 342

15.4 Mustikkamaki Pegmatite, Finland 343

15.5 Summary 343

References 343

Part III Geochemistry of Radiogenic Isotopes 345

16 Mixing Theory 347

16.1 Chemical Compositions of Mixtures 347

16.2 Isotopic Mixtures of Sr 350

16.3 Isotopic Mixtures of Sr and Nd 352

16.4 Three-Component Isotopic Mixtures 355

16.5 Applications 356

16.6 Summary 361

References 361

17 Origin of Igneous Rocks 363

17.1 The Plume Theory 363

17.2 Magma Sources in the Mantle 364

17.3 Midocean Ridge Basalt 365

17.4 Basalt and Rhyolite of Iceland 369

17.5 The Hawaiian Islands 375

17.6 HIMU Magma Sources of Polynesia 380

17.7 Subduction Zones 382

17.8 Continental Flood Basalt 389

17.9 Alkali-Rich Lavas 394

17.10 Origin of Granite 399

17.11 Summary 405

References 406

18 Water and Sediment 412

18.1 Strontium in Streams 412

18.2 Sediment in Streams 419

18.3 Zaire and Amazon Rivers 426

18.4 Summary 433

References 433

19 The Oceans 436

19.1 Strontium in the Phanerozoic Oceans 436

19.2 Strontium in the Precambrian Oceans 447

19.3 Neodymium in the Oceans 451

19.4 Lead in the Oceans 463

19.5 Osmium in Continental Runoff 470

19.6 Osmium in the Oceans 475

19.7 Hafnium in the Oceans 480

19.8 Summary 486

References 487

Part IV Short-Lived Radionuclides 495

20 Uranium/Thorium-Series Disequilibria 497

20.1 ²³⁸U/²³⁴U–²³⁰Th-Series Geochronometers 498

20.2 Radium 508

20.3 Protactinium 516

20.4 Lead-210 521

20.5 Archeology and Anthropology 527

20.6 Volcanic Rocks 531

20.7 Magma Formation 535

20.8 Summary 539

References 540

21 Helium and Tritium 546

21.1 U–Th/He Method of Dating 546

21.2 Thermochronometry 551

21.3 He Dating of Iron-Ore Deposits 554

21.4 Tritium–³He Dating 555

21.5 Meteorites and Oceanic Basalt 560

21.6 Continental Crust 566

21.7 Summary 571

References 572

22 Radiation-Damage Methods 577

22.1 Alpha-Decay 577

22.2 Fission Tracks 580

22.3 Applications of Fission-Track Dates 592

22.4 Thermoluminescence 595

22.5 Electron-Spin Resonance 603

22.6 Summary 606

References 608

23 Cosmogenic Radionuclides 613

23.1 Carbon-14 (Radiocarbon) 614

23.2 Beryllium-10 and Aluminum-26 (Atmospheric) 625

23.3 Exposure Dating (¹⁰Be and ²⁶Al) 633

23.4 Cosmogenic and Thermonuclear ³⁶Cl 639

23.5 Meteorites 641

23.6 Other Long-Lived Cosmogenic Radionuclides 646

23.7 Summary 646

References 647

24 Extinct Radionuclides 654

24.1 The Pd–Ag Chronometer 655

24.2 The Al–Mg Chronometer 657

24.3 The Hf–W Chronometer 659

24.4 FUN in the Solar Nebula 662

24.5 Summary 663

References 664

25 Thermonuclear Radionuclides 667

25.1 Fission Products and Transuranium Elements 667

25.2 Strontium-90 in the Environment 672

25.3 Cesium-137 in the Environment 678

25.4 Arctic Ocean: ⁹⁰Sr/¹³⁷Cs, ^239,240Pu, and ²⁴¹Am 682

25.5 Summary 686

References 687

Part V Fractionation of Stable Isotopes 691

26 Hydrogen and Oxygen 693

26.1 Atomic Properties 693

26.2 Mathematical Relations 695

26.3 Meteoric Precipitation 697

26.4 Paleothermometry (Carbonates) 704

26.5 Silicate Minerals and Rocks 709

26.6 Water–Rock Interactions (Rocks) 714

26.7 Water–Rock Interactions (Water) 718

26.8 Clay Minerals 725

26.9 Marine Carbonates 727

26.10 Marine Phosphates 730

26.11 Biogenic Silica and Hydroxides of Fe and Al 735

26.12 Chert (Phanerozoic and Precambrian) 736

26.13 Extraterrestrial Rocks 738

26.14 Summary 743

References 744

27 Carbon 753

27.1 Biosphere 754

27.2 Life in the Precambrian Oceans 757

27.3 Fossil Fuel 761

27.4 Carbon-Isotope Stratigraphy (Phanerozoic) 763

27.5 Precambrian Carbonates 768

27.6 Igneous and Metamorphic Rocks 774

27.7 Extraterrestrial Carbon 785

27.8 Search for Life on Mars 790

27.9 Summary 792

References 793

28 Nitrogen 803

28.1 Geochemistry 803

28.2 Isotope Fractionation 805

28.3 Nitrogen on the Surface of the Earth 806

28.4 Fossil Fuels 808

28.5 Igneous Rocks and the Mantle 811

28.6 Ultramafic Xenoliths 812

28.7 Diamonds 813

28.8 Meteorites 815

28.9 Moon 817

28.10 Mars 818

28.11 Summary 820

References 820

29 Sulfur 824

29.1 Isotope Geochemistry 824

29.2 Biogenic Isotope Fractionation 825

29.3 Sulfur in Recent Sediment 827

29.4 Fossil Fuels 828

29.5 Native Sulfur Deposits 830

29.6 Sedimentary Rocks of Precambrian Age 831

29.7 Isotopic Evolution of Marine Sulfate 833

29.8 Igneous Rocks 835

29.9 Sulfide Ore Deposits 840

29.10 Sulfur in the Environment 843

29.11 Mass-Independent Isotope Fractionation 846

29.12 Summary 847

References 849

30 Boron and Other Elements 854

30.1 Boron 855

30.2 Lithium 859

30.3 Silicon 863

30.4 Chlorine 868

30.5 Postscript 870

References 870

Index 875

International Geological Timescale (2002) 897