Isatope dating immunofacts online dating
Based on the assumptions of basic radioactive dating, the problem of an unknown initial amount of daughter isotope is eliminated by the definition of the isochron itself. If contamination has occurred within a sample, the ratios from the sample shouldn't fall on a line.
Instead, the points would be in a scatter on the graph.
As time progresses, the line connecting the measurements within the sample moves counter-clockwise around a point intersecting the y-axis, a point that represents the initial ratios (Dalrymple 20).
Once the ratios are plotted, the age of the rock being dated can be determined based on the slope of the line.
The key to the formation of crystals in the rock is that the process is selective between elements, but is indifferent to isotopes of the same element.
According to Brent Dalrymple (20-69), "the trick to the isochron diagram is the normalization of both parent and daughter isotope to a third isotope." This third isotope is the non-decay product isotope of the same element as the daughter element.
In the initial state, the graph of daughter isotope to the third isotope versus parent isotope to the third isotope should result in a straight, horizontal line.
This amount is often unknown and is one of the downfalls of conventional radiometric dating.
However, isochron dating bypasses this assumption, as explained below. The final condition is the number of atoms of parent and daughter isotopes remaining in the rock and can easily be measured in a lab.
Isochron dating bypasses the necessity of knowing the quantity of initial daughter product in the rock by not using that value in the computation.