Stable Isotope Ratios in Calcareous Skeletons		  
 
Most chemical elements occur in several stable isotops , i.e. atoms that differ in the number of neutrons in the core but do not disintegrate spontaneously, i.e. are not radioactive. These isotopes differ slightly in their physical and biochemical properties.
Regarding the element oxygen, 16O (8 protons + 8 neutrons) and 18O (8 protons + 10 neutrons) are the most common stable isotopes.
Regarding the element carbon, 12C (6 protons + 6 neutrons) and 13C (6 protons + 7 neutrons) are the most common stable isotopes.

Stable isotope ratios 18O and 13C are computed by

18O =
 [ (18O/16O)sample / (18O/16O)standard  -1] * 103 per mil
13C =
[ (13C/12C)sample / (13C/12C)standard  -1] * 103 per mil

Certain fossile carbonates such as "Vienna Pee Dee Belemnite" (VPDB) are used as standards.

  
 
In the following, we will discuss
- Basic chemistry of calcareous skeleton formation
- Parameters affecting stable oxygen isotope ratios 18O in skeleton CaCO3
- Parameters affecting stable carbon isotope ratios 13C in skeleton CaCO3
- Technics and methods

For further information refer to Krantz et al. (1987) and Wefer & Berger (1991).

  
 

Introduction
Chemistry
18O
 13C Methods