Radiocarbon dating after 1950 420 friendly dating
Should a point plot below the line, it could indicate that a particular sample was open to migration of the dating elements or that the sample was contaminated and lay below the isochron when the rock solidified.
Rubidium–strontium (Rb–Sr) dating was the first technique in which the whole rock isochron method was extensively employed.
Certain rocks that cooled quickly at the surface were found to give precisely defined linear isochrons, but many others did not.
Some studies have shown that rubidium is very mobile both in fluids that migrate through the rock as it cools and in fluids that are present as the rock undergoes chemical weathering.
In both cases, approximate ages that have a degree of validity with respect to one another result, but they are progressively less reliable as the assumptions on which the model is calculated are violated.
In uranium–lead (U–Pb) dating of zircon, the zircon is found to exclude initial lead almost completely.
Minerals, too, are predictable chemical compounds that can be shown to form at specific temperatures and remain closed up to certain temperatures if a rock has been reheated or altered.
When a single body of liquid rock crystallizes, parent and daughter elements may separate so that, once solid, the isotopic data would define a series of points, such as those shown as open circles designated R.
With time each would then develop additional daughter abundances in proportion to the amount of parent present.
Search for radiocarbon dating after 1950:
If a simple mineral is widespread in the geologic record, it is more valuable for dating as more units can be measured for age and compared by the same method.