Dating uranium 238 speed dating san antonio texas
“Depending on the history of the rock, we can date things nowadays down to something on the order of a few hundredths of a percent of its age,” answers Mueller.That translates, for example, to plus or minus a million years out of three billion.“One is a relative time, meaning if there’s a mineral of one kind, and growing around it is a mineral of a second kind, you know the inner mineral formed first, but you don’t know how much time elapsed between the two.” Henry evaluates these kinds of mineral relations in rocks.From the types of minerals and their distributions in the rocks he reconstructs a relative sequence of events that reflects the change over time of parameters like pressure, temperature, and deformation. Henry, “I can use the types of minerals and their chemistry to determine the conditions that the rock had experienced at some point in its history.
(The half-life is the time it takes for half of the original radioactive isotope to change to another element.) In comparison, the half-life of the radioactive uranium 238 isotope is 4.5 billion years, which makes it useful for dating extremely old materials. “You go out and look for relative age relationships, see which rock unit was formed first,” says Henry.Quantitative microanalysis of the elements in zircon is done with an electron microprobe.