Dating techniques based on radioactive decay
The relationship between the two is: T = 0.693 / λ Many different radioactive isotopes and techniques are used for dating.
All rely on the fact that certain elements (particularly uranium and potassium) contain a number of different isotopes whose half-life is exactly known and therefore the relative concentrations of these isotopes within a rock or mineral can measure the age.
However, there is a limited range in Sm-Nd isotopes in many igneous rocks, although metamorphic rocks that contain the mineral garnet are useful as this mineral has a large range in Sm-Nd isotopes.
This technique also helps in determining the composition and evolution of the Earth's mantle and bodies in the universe.
This technique is used on ferromagnesian (iron/magnesium-containing) minerals such as micas and amphiboles or on limestones which also contain abundant strontium.
This method faces problems because the cosmic ray flux has changed over time, but a calibration factor is applied to take this into account.
Another way of expressing this is the half-life period (given the symbol T).
The half-life is the time it takes for half of the parent atoms to decay.
The isotopes are then measured within the same machine by an attached mass spectrometer (an example of this is SIMS analysis).
This is a common dating method mainly used by archaeologists, as it can only date geologically recent organic materials, usually charcoal, but also bone and antlers.
Search for dating techniques based on radioactive decay:
This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.