Zircon dating metamorphic rocks marital dating online
Scientists have many ways to discover how old rocks and fossils are.The ratio of lead versus uranium in the zircon is what is used to determine the age of the rock. As you know, radioisotopes do not decay directly into a stable state; rather they go through stages of radioactive decay until reaching a stable isotope. Since igneous rocks have no fossils, this makes zircon valuable in dating them. Scientists can use monazite, titanite, baddeleyite and zirconolite for uranium dating. Zircon is commonly found as the primary mineral in igneous rocks.Different zones of a single zircon grains also often preserve different ages reflecting a complex thermal history that they have undergone (e.g.
The half-life of the uranium series is 4.47 billion years, and the half-life of the actinium series is 710 million years.The older they get, the farther out along the curve they go. However, even though zircon is very strong, sometimes a geological event occurs that allows lead to escape.This makes the zircons go straight back to the starting point on the Concordia graph, off of their original line. As long as no other geological event occurs, the whole Discordia line moves along the Concordia line, pointing to the age of the geological event that caused the disturbance.In another 710 million years, there would be only one 235U atom for every three 207Pb atoms.In the uranium series, the half-lives of the minerals are much longer, but the process is the same.