Absolute Age Determination: Physical and Chemical Dating Methods and Their Application

ISBN-13: 9783540512769 / Angielski / Miękka / 1990 / 505 str.

Mebus A. Geyh; Helmut Schleicher; Clark Newcomb

Opis

With the growing recognition during the last two centuries that the Earth has an immense age and processes over long periods of time have changed the morphology and composition of the Earth's crust, geologists have become increasingly interested in determination of absolute ages. A rela tive geochronology was established on the basis of the lithostratigraphic and biostratigraphic principles developed during the last century. With the discovery of radioactivity, the basis for a new geoscientific discipline - geochronology - was established (Rutherford 1906). It is the study of geological time, based mainly on the time signatures provided by the isotopic composition in geologic materials. The isotopic signature in a rock yields more information than that provided by the geochemical signature alone because it reflects the origin and history of the element in the rock. The aim of geochronology is to calibrate and standardize chronostrati graphic scales, to develop geological time scales that have a sensitive or at least useful resolution in order to place the geological events in the correct chronological order, and to assign their proper time spans. In practice, the application of geochronology is much wider because the data in the "natural archives" often provide information on the origin, genesis, and history of the materials. This, of course, requires an understanding of the geochemical behavior of the substances involved."

Spis treści

1 Introduction.- 2 Time Scales and Ages.- 2.1 Absolute Time Scales.- 2.2 Relative Time Scales.- 2.3 Physical and Chemical Time Scales.- 3 Selection, Collection, Packing, Storage, Transport, and Description of the Samples.- 3.1 Selection and Collection of the Samples.- 3.2 Packing, Storage, and Transport of the Samples.- 3.3 Sample Description.- 4 Treatment and Interpretation of the Raw Data.- 4.1 Suitability of a Sample for Dating and Reliability of the Dates.- 4.1.1 Soft-Rock Dating.- 4.1.2 Hard-Rock Dating.- 4.1.3 Isotope Geochemistry.- 4.2 Mathematical Evaluation of Physical and Chemical Age Data.- 4.2.1 Rules for Simple Calculations with the Dating Results; Statistical Tests.- 4.2.2 Comparison of Age Values.- 4.2.3 Numerical and Graphical Evaluation of Age Values.- 4.3 Publication of the Age Values.- 5 Physical Dating Methods.- 5.1 Principles.- 5.2 Sample Treatment and Measurement Techniques.- 5.2.1 Sample Treatment.- 5.2.1.1 Hard-Rock Samples.- 5.2.1.2 Soft-Rock Samples.- 5.2.2 Radioactivity Measurements: Decay Counting Methods.- 5.2.2.1 Gas-Filled Proportional and Geiger-Müller Counters.- 5.2.2.2 Scintillation Counters.- 5.2.2.3 Semiconductor Detectors.- 5.2.3 Measurement of Stable and Long-Lived Isotopes: Atom Counting Methods.- 5.2.3.1 Mass Spectrometry (MS).- 5.2.3.2 Accelerator Mass Spectrometry (AMS).- 5.2.3.3 Resonance-Ionization Spectrometry (RIS).- 5.2.4 Other Analytical Techniques.- 5.2.4.1 Isotope Dilution Analysis (ID).- 5.2.4.2 Neutron Activation Analysis (NAA).- 5.2.4.3 Flame Photometry, Atomic Absorption Spectrometry (AA) and Inductive Coupled Plasma Analysis (ICP).- 5.2.4.4 Ion-Microprobe (IMP) and Laser Microprobe Mass Analysis (LAMMA).- 5.2.4.5 X-Ray Fluorescence Analysis (XRF).- 6 Radiometric Dating Methods.- 6.1 Parent/Daughter Isotope Ratios as a Geochronometer.- 6.1.1 Potassium/Argon (40K/40Ar) Method***.- 6.1.1.1 Conventional Potassium/Argon (40K/40Ar) Method***.- 6.1.1.2 Argon/Argon (39Ar/40Ar) Method**.- 6.1.2 Potassium/Calcium (40K/40Ca) Method *.- 6.1.3 Rubidium/Strontium (87Rb/87Sr) Method***.- 6.1.4 Lanthanum/Cerium (138La/138Ce) Method.- 6.1.5 Lanthanum/Barium (138La/138Ba) Method.- 6.1.6 Samarium/Neodymium (147Sm/143Nd) Method**.- 6.1.7 Lutetium/Hafnium (176Lu/176Hf) Method *.- 6.1.8 Rhenium/Osmium (187Re/187Os) Method *.- 6.1.9 Uranium/Thorium/Lead Methods *** (238U/206Pb, 235U/207Pb, and 232Th/208Pb Methods).- 6.1.10 Common Lead Method *.- 6.1.11 Lead/Lead (207Pb/206Pb) Method *.- 6.1.12 Chemical Lead Method.- 6.1.13 Lead/Alpha Method (Larsen Method).- 6.1.14 Krypton/Krypton (Krsf/Krn) Method*.- 6.1.15 Xenon Methods *.- 6.1.15.1 Uranium/Xenon (U/Xesf) Method.- 6.1.15.2 Xenon/Xenon (Xesf/Xen) Method *.- 6.2 Dating with Cosmogenic Radionuclides.- 6.2.1 Radiocarbon (14C) Method***.- 6.2.2 Tritium (3H) Methods.- 6.2.2.1 Classical Tritium (3H) Method *.- 6.2.2.2 Tritium/Helium-3 (3H/3He) and Helium-3 (3He) Methods**.- 6.2.3 Beryllium-10 (10Be) Method**.- 6.2.4 Sodium-22 (22Na) Method.- 6.2.5 Aluminium-26 (26Al) Method *.- 6.2.6 Silicon-32 (32Si) Method *.- 6.2.7 Chlorine-36 (36Cl) Method**.- 6.2.8 Argon-39 (39Ar) Method**.- 6.2.9 Calcium-41 (41Ca) Method.- 6.2.10 Manganese-53 (53Mn) Method**.- 6.2.11 Krypton-81 (81Kr) Method *.- 6.2.12 Iodine-129 (129I) Method *.- 6.2.13 Aluminium-26/Beryllium-10 (26Al/10Be) Method *.- 6.2.14 Beryllium-10/Chlorine-36 (10Be/36Cl) Method.- 6.3 Dating Based on Radioactive Disequilibrium of the Uranium, Thorium, and Protactinium Decay Series: The Uranium/Thorium/Protactinium Methods ***.- 6.3.1 23OTh/234U Method***.- 6.3.2 231Pa/235U Method *.- 6.3.3 231Pa/230Th Method**.- 6.3.4 234U/238U Method**.- 6.3.5 230Th-excess Method**.- 6.3.6 231Pa-excess Method *.- 6.3.7 230Th-excess/232Th or 230Th/238U Method**.- 6.3.8 231Pa-excess/230Th-excess Method**.- 6.3.9 234Th-excess Method.- 6.3.10 228Th-excess/232Th Method.- 6.3.11 Dating Methods Based on Supported 226Ra and Unsupported 226Ra.- 6.3.12 224Ra and 228Ra Methods.- 6.3.13 210Pb Method***.- 6.3.14 Uranium/Helium (U/He) Method**.- 6.3.15 Radium/Radon Method.- 6.4 Age Determination Using Radiation Damage.- 6.4.1 Thermoluminescence (TL) Method***.- 6.4.2 Optical Dating (OSL) Method *.- 6.4.3 Electron Spin Resonance (ESR or EPR) Method**.- 6.4.4 Exo-Electron Method (TSEE Method) *.- 6.4.5 Thermally Stimulated Current (TSC) Method.- 6.4.6 Differential Thermoanalysis (DTA).- 6.4.7 Fission Track Method (FT Method)***.- 6.4.8 Alpha-Recoil Track Method.- 6.4.9 Age Determination Using Pleochroic Haloes.- 6.5 Dating Meteorites and Lunar Rocks.- 6.5.1 Introduction.- 6.5.2 Sample Preparation and Measurement.- 6.5.3 Formation Interval.- 6.5.4 Solidification Ages.- 6.5.5 Gas Retention Ages.- 6.5.6 Cosmic Ray Exposure Ages.- 6.5.7 Terrestrial Ages of Meteorites.- 7 Chronostratigraphic Methods Using Global Time Markers.- 7.1 Paleomagnetic Dating Methods***.- 7.2 Chronostratigraphic Time-Scale Using ?18O Values ***.- 7.3 Chronostratigraphic Time-Scale Using ?34S and ?13C Values and 87Sr/86Sr Ratios**.- 7.4 Artificial Radionuclides as Time Markers ***.- 7.5 Geochemical Time Markers *.- 7.6 Chemical Pollution as Time Markers *.- 8 Chemical Dating Methods.- 8.1 Amino-Acid Racemization Method (AAR)***.- 8.2 Amino-Acid Degradation Method.- 8.3 Dating of Bones Using the Nitrogen or Collagen Content *.- 8.4 Chemical Electron-Spin-Resonance (ESR) Dating.- 8.5 Molecular (Protein and DNA) Clocks.- 8.6 Obsidian Hydration Method***.- 8.7 Dating of Man-Made Glass.- 8.8 Calcium Diffusion and Cation-Ratio Methods.- 8.9 Dating of Bones Using the Fluorine or Uranium Content *.- 9 Phanerozoic Time-Scale.- 9.1 Objectives and History of Geochronolgy.- 9.2 Geological Time-Scales.- 9.3 The Future.- 10 Literature.- 10.1 Journals that Frequently Publish Geochronological Papers.- 10.2 Geochronology Textbooks.- 10.3 References.- Acknowledgments.- Appendix A: Geochronology Glossary.- Appendix B: Radioactive and Stable Isotopes in Geochronology.- Appendix C: List of Addresses.