Measure isotopes for radiometric dating Chatitalianefree
Now imagine that you have a rock sample that contains 39% uranium-235 and 61% lead-207. At around 1000 million years (i.e., one billion years), as shown on the graph at right above.
With modern techniques, these ranges have gotten narrower and narrower, and consequently, even very ancient rocks can be dated quite precisely.
How can the formation of a rock be correlated with a particular ancient event?
The answers to all of these questions lie in our understanding of the geologic processes that affect the deposition of radioactive elements.
The zircon formation may have occurred tens to hundreds of thousands of years before the eruption and deposition.
However, when dealing with rocks that are hundreds of millions of year old, the time between zircon formation and eruption really is short in comparison.
Radioactive decay Radioisotopic dating relies on the process of radioactive decay, in which the nuclei of radioactive atoms emit particles.