Strontium dating

In addition, they have had to develop special techniques with which to dissolve these highly refractory minerals without contaminating the small amount (about one-billionth of a gram) of contained lead and uranium on which the age must be calculated.Since parent uranium atoms change into daughter atoms with time at a known rate, their relative abundance leads directly to the absolute age of the host mineral.

strontium dating-78

rubidium-87 that was present in the rock at the time of its formation.

Rubidium-87 comprises 27.85 percent of the total atomic abundance of rubidium, and of the four isotopes of strontium, only strontium-87 is formed by its decay.

Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated.

Some method of correlating rock units must be found.

The same margin of error applies for younger fossiliferous rocks, making absolute dating comparable in precision to that attained using fossils.

To achieve this precision, geochronologists have had to develop the ability to isolate certain high-quality minerals that can be shown to have remained closed to migration of the radioactive parent atoms they contain and the daughter atoms formed by radioactive decay over billions of years of geologic time.

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A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered.

It should be emphasized that linking sites together is essential if the nature of an ancient society is to be understood, as the information at a single location may be relatively insignificant by itself.

Without absolute ages, investigators could only determine which fossil organisms lived at the same time and the relative order of their appearance in the correlated sedimentary rock record.

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