Rb sr dating
Strontium is a soft metal like lead and, when freshly cut, has a silvery lustre.
It rapidly reacts in air to take on a yellowish colour; therefore, it must be protected from oxygen for storage. Although it is widely distributed with calcium, there are only two principal ores of strontium alone, celestine (Sr SO).
Under controlled conditions, however, it has been used for treatment of some superficial cancers and bone cancer.
It is also used as a source in thickness gauges and has been used in radioisotope thermoelectric generators, where the heat of its radioactive decay is converted to electricity for long-lived, lightweight power sources in navigation buoys, remote weather stations, and space vehicles.
Strontium-89 is employed in the treatment of bone cancer, as it targets bone tissues, delivers its beta radiation, and then decays in a few months’ time (half-life 51 days).
Strontium is not an essential element for higher life-forms, and its salts are generally nontoxic.
With the development of modern radiometric dating methods in the late 1940s and 1950s, it was possible for the first time not only to measure the lengths of the eras, periods, and epochs but also to check the relative order of these geologic time units.
Radiometric dating verified that the relative time scale determined by stratigraphers and paleontologists (Figure 1) is absolutely correct, a result that could only have been obtained if both the relative time scale and radiometric dating methods were correct.
There can be no doubt about the Earth’s antiquity; the evidence is abundant, conclusive, and readily available to all who care to examine it.
Nonetheless, stratigraphy and radiometric dating of Precambrian rocks have clearly demonstrated that the history of the Earth extends billions of years into the past.
Radiometric dating has not been applied to just a few selected rocks from the geologic record.
This variation is used in dating geological samples and in identifying the provenance of skeletons and clay artifacts.
About 16 synthetic radioactive isotopes have been produced by nuclear reactions, of which the longest-lived is strontium-90 (28.9-year half-life).