Ranges for most natural materials are as follows: U-Pb, Th-Pb, and Pb-Pb isotopic ratios may be used in age dating and petrogenetic tracing of igneous, metamorphic, and hydrothermal rocks.
Radiocarbon, potassium-argon, fission track, and thermoluminescence dating all rely on this phenomenon in different ways.
CATEGORY: technique DEFINITION: A technique based on the relative abundance of lead isotopes, which differ according to the origin of the lead, allowing scientists to pinpoint the source of a piece of lead once the ratios of the isotopes have been determined.
CATEGORY: geology DEFINITION: Atoms of the same element that have different atomic masses due to having different numbers of neutrons in the nuclei, but which still have similar chemical properties.
Many of these forms of elements with a specific number of electrons (such as carbon 14 or potassium 40) are unstable and decay into different elements, releasing their surplus electrons.
SYNONYMS OR RELATED TERMS: stable carbon isotope analysis CATEGORY: technique DEFINITION: A technique for reconstructing past diets (plant foods) by analyzing the isotopic ratios, particularly carbon and nitrogen, contained in human bone.
Human remains are analyzed for a measurement of the ratio between 13C and 12C isotopes in ancient human bone collagen.Since there is only one nonradiogenic isotope, instrument fractionation cannot be corrected (see Sr-Rb), thus, care must be taken when running a sample. Because it is very easily contaminated; clean lab techniques are required.Pb isotopes are reported as a ratio with respect to the non-radiogenic isotope, Pb.SYNONYMS OR RELATED TERMS: oxygen isotope examination CATEGORY: technique DEFINITION: Isotope analysis looking at the O18/O16 ratio in materials.The method can be used to classify glass types and to analyze mollusk shells in order to try and reconstruct their original environment and thus the source. The basis for this technique is the fact that the ratio of two of the stable isotopes of oxygen varies according to the material in which it is found.Libby's conclusion, with allowance for SYNONYMS OR RELATED TERMS: deep sea core dating, deep-sea cores CATEGORY: technique DEFINITION: A technique used in the analysis of data from oceanic sediments in which the material retrieved by the core yields information on temperature changes in the ocean through time. Since these organisms have different temperature preferences depending on species, the relative abundance of the various species changes as the temperature alters.