Isotope dating techniques

Uranium-series dating is by far the most widely-used dating technique applied to speleothems, and is only applicable to material that is currently in a state of disequilibrium. Given the rates of ingrowth of daughter isotopes of Pa and °Th, conditions of uranium-series disequilibrium in systems which have remained isotopically-closed are generally restricted to materials < 500 ka... 

A more recently developed technique, known as the accelerator mass spectrometry (AMS) radiocarbon dating technique, based on counting, in a mass spectrometer, the relative amount of radiocarbon to stable carbon isotopes in a sample (see Textbox 10). 

With respect to interpretation, the existence of alternative dating techniques has made clear the necessity for and the difficulty of this step. That is, nature seldom provides ideal dating systems with fixed injection rates, negligible losses, and constant temperature. As a result, simple dates based upon observed isotopic ratios and nuclear half-lives, for example, frequently require cautious interpretation before they can serve as accurate... 

During the past several years exciting advances have taken place in radioactive dating techniques—advances which have made it possible to determine unusually small isotope ratios and to determine the radioisotopic composition of individual chemical fractions and particle size fractions of extremely small samples. 

Summary of Isotope Dating Techniques and Half-Life... 

Because radioactive isotopes seem to decay at very constant rates, they can be used as clocks. One of the first radioactive dating techniques involved the use of the radioisotope carbon-14. Carbon-14 is produced in the upper atmosphere when neutrons (produced by cosmic rays from space) collide with nitrogen-14 molecules in the reaction shown below ... 

For discussion on further additional dating techniques the interested reader may consult references on dendrochronology (28,29,31,59, 60, 79), tritium dating (38, 80), and oxygen isotope dating (59, 81,82). 

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