U pb dating wiki
The time that it takes for half of a sample to decay is known as the half life of the isotope.
Some isotopes have half lives longer than the present age of the universe , but they are still subject to the same laws of quantum physics and will eventually decay, even if doing so at a time when all remaining atoms in the universe are separated by astronomical distances.
Several half-lives can pass and still leave measurable amounts radioactive carbon present in the sample.
Radiocarbon dating is so well-known because it can be applied to nearly any organism that was living at some time.
Zircon is a fairly abundant mineral that exists in many forms in the environment, and because of its chemical structure Uranium is easily incorporated into its molecules.
However, Lead is not easily incorporated into the Zircon molecules; therefore, when a sample of Zircon is analyzed any lead that is found must have come directly from Uranium decay.
Various elements are used for dating different time periods; ones with relatively short half-lives like carbon or 14 C are useful for dating once-living objects since they include atmospheric carbon from when they were alive from about ten to fifty thousand years old.
U decays to Pb, and U decays to Pb These two decay pathways have different half-lives that have been measured and recorded.While radiocarbon dating is very useful in cases where organic matter is being analyzed, in many cases the samples that are being dated were never alive.