1 Introduction and Basic Principles of Isotope
Geochemistry
This book does not pretend to be complete. For example, we do not consider
stable isotopes in any great depth, but instead concentrate on the radiogenic
isotopic systems such as Rb-Sr, Sm-Nd, U-Pb, etc. Stable isotope systems are
dealt with in more detail in the books of Kyser (1987) and Arthur and Anderson
eds. (1983). Special topics within the field of sedimentary isotope geochemistry
are dissected and discussed in the book "Isotopic signatures and sedimentary
records" (Clauer and Chaudhuri 1992). Information about the dynamics of isotope
systems in clays is given in the book "Clays in crustal environments" (Clauer and
Chaudhuri 1995). Various applications of the uranium decay series for the study
of sedimentary and aquatic systems are not covered in this book as they are
already dealt with in a comprehensive text book (Ivanovich and Harmon 1992).
This first chapter is concerned with some of the most important basic parameters
in isotope geochemistry and will help in the reading and understanding of the
chapters that follow. A more comprehensive treatment with detailed references is
given in G. Faure's standard work, "Principles of Isotope Geology".
1.1 S t a b l e I s o t o p e s
It is generally understood that the isotopic composition of the stable isotopes is
represented as the relative enrichment of the heavier to the lighter isotope. In order
to represent the isotopic composition of hydrogen, the deuterium (D= 2H) -
hydrogen ratio (D/H) is used. Similarly, the ratio 180/160 is used to represent the
isotopic composition of oxygen; the ratio 13C/12C for carbon and the ratio 345/32S
for sulfur. All these isotopic compositions are commonly presented as isotopic
enrichments relative to internationally recognized standards:
Geochemistry
This book does not pretend to be complete. For example, we do not consider
stable isotopes in any great depth, but instead concentrate on the radiogenic
isotopic systems such as Rb-Sr, Sm-Nd, U-Pb, etc. Stable isotope systems are
dealt with in more detail in the books of Kyser (1987) and Arthur and Anderson
eds. (1983). Special topics within the field of sedimentary isotope geochemistry
are dissected and discussed in the book "Isotopic signatures and sedimentary
records" (Clauer and Chaudhuri 1992). Information about the dynamics of isotope
systems in clays is given in the book "Clays in crustal environments" (Clauer and
Chaudhuri 1995). Various applications of the uranium decay series for the study
of sedimentary and aquatic systems are not covered in this book as they are
already dealt with in a comprehensive text book (Ivanovich and Harmon 1992).
This first chapter is concerned with some of the most important basic parameters
in isotope geochemistry and will help in the reading and understanding of the
chapters that follow. A more comprehensive treatment with detailed references is
given in G. Faure's standard work, "Principles of Isotope Geology".
1.1 S t a b l e I s o t o p e s
It is generally understood that the isotopic composition of the stable isotopes is
represented as the relative enrichment of the heavier to the lighter isotope. In order
to represent the isotopic composition of hydrogen, the deuterium (D= 2H) -
hydrogen ratio (D/H) is used. Similarly, the ratio 180/160 is used to represent the
isotopic composition of oxygen; the ratio 13C/12C for carbon and the ratio 345/32S
for sulfur. All these isotopic compositions are commonly presented as isotopic
enrichments relative to internationally recognized standards: