Abstract

Post-depositional alteration of skeletal material is a problem that has long plagued isotopic analysis of archaeological material. Diagenesis, the term used to describe the post-depositional alteration, may be physical, chemical or biological in nature, and calls into question the reliability of isotopic data. Specifically, microbial diagenesis has the potential impact of altering isotopic signatures in skeletal material through decomposition by soil microorganisms. The objective of my thesis has been to identify diagenetically altered areas within bone and determine to what extent the isotopic signals have been altered. Modern bone and dentition samples were subjected to microbial degradation in a natural environment and the extent of bacterial colonization of differing skeletal tissue layers was identified using scanning electron microscopy. Areas recognized as potentially having undergone microbial diagenesis are targeted for isotope analysis using a CO2 laser ablation system; ideal for spot analysis on rare or small specimens. Archaeological samples were also analyzed in an attempt to identify patterns in the colonization or offsets in isotope values over time. Variation in the degree of colonization of differing areas of the bone and also in the carbon and oxygen isotope values obtained from altered versus unaltered areas is investigated. These results not only further our knowledge of the process of biodegradation but allow for more accurate isotope analysis of archaeological material through the creation of a diagenetic profile within skeletal material resulting from microbial diagenesis.