Palaeomagnetism and archaeomagnetism are fascinating specialized studies because they are applicable to such a wide range of problems in geology, archaeology and geophysics. They can also be undertaken cheaply, when compared with most other geophysical techniques, and, at first sight, simply. In fact, real comprehension of the magnetic processes that have occurred in rocks and other types of material over several thousands or many millions of years is still extremely difficult to assess and measure. On this basis, this book cannot explain all such features, nor can it attempt to cover all the actual and potential applications of the method. All that can be attempted is to give an impression of the ways in which such techniques can be used in a wide variety of fields, and how these techniques are usually applied. The magnetization of rocks is, in fact, one of the earliest of the true sciences, but we are still not in a position to answer many of the problems posed. Consequently some of the examples given of applications are, essentially, state-of-the-art comments, rather than being a review as such. The changing position of the geomagnetic poles with time is still not adequately defined, for example, and some of the more recent conventional views are given, although the emphasis is placed on more subjective, probably more controversial, evaluations.
Auflage
Sprache
Verlagsort
Verlagsgruppe
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ISBN-13
978-94-009-5955-2 (9789400959552)
DOI
10.1007/978-94-009-5955-2
Schweitzer Klassifikation
1 Introduction.- 1.1 Scope of the book.- 1.2 Historical perspective.- 1.3 Data presentation, magnetic units and geological ages.- 2 The physical basis.- 2.1 Magnetization on an atomic scale.- 2.2 Magnetic domains and anisotropy.- 2.3 Temperature, grain size and time.- 3 Magnetic mineralogy and magnetic identification of minerals.- 3.1 Introduction.- 3.2 Magnetic minerals.- 3.3 Identification of magnetic minerals.- 4 The magnetization of natural materials.- 4.1 Introduction.- 4.2 Igneous rocks.- 4.3 Unconsolidated sediments and sedimentary rocks.- 4.4 Metamorphic rocks.- 4.5 Archaeological materials.- 4.6 Secondary magnetizations.- 4.7 Magnetic inhomogeneity and anisotropy.- 4.8 Summary.- 5 Sampling, measurement and procedures.- 5.1 Introduction.- 5.2 Sampling and orientation.- 5.3 Measurements of remanence, low-field susceptibility and anisotropy.- 5.4 The stability of remanence.- 5.5 The age of the remanence.- 5.6 Palaeointensities.- 5.7 Summary.- 6 Statistical and mathematical analyses.- 6.1 Introduction.- 6.2 Intensity of remanence and susceptibility.- 6.3 Directional analyses.- 6.4 Analyses of vector components and their stability.- 6.5 Levels of direction analyses and sampling numbers.- 6.6 Magnetic fabric.- 7 Archaeological applications.- 7.1 Introduction.- 7.2 Archaeomagnetic dating.- 7.3 Other applications.- 8 Geomagnetic applications.- 8.1 Introduction.- 8.2 The present geomagnetic field and historical observations.- 8.3 Secular variations and the drift of the non-dipole field.- 8.4 Polarity reversals, transitions and excursions.- 8.5 The general nature of the geomagnetic field.- 9 Geological applications.- 9.1 Introduction.- 9.2 Magnetic dating.- 9.3 Magnetic fabric.- 9.4 Sedimentological applications.- 9.5 Igneous and metamorphic rocks.- 9.6 Structural applications.- 9.7 Biological, weather, climatic, palaeontological and palaeogeographic aspects.- 9.8 Extraterrestrial studies.
