Carbon dating uranium
With this background in the uranium-lead method, you may have a deeper appreciation of the research presented on the University of Wisconsin's "Earliest Piece of the Earth" page, including the 2001 paper in Nature that announced the record-setting date.When asked for your age, it's likely you won't slip (with the exception of a recent birthday mistake).The best estimate for Earth's age is based on radiometric dating of fragments from the Canyon Diablo iron meteorite.From the fragments, scientists calculated the relative abundances of elements that formed as radioactive uranium decayed over billions of years."It was not until the 1950s that the age of the universe was finally revised and put safely beyond the age of the Earth, which had at last reached its true age of 4.56 billion years," Lewis said.Dating a rock involves uranium-lead measurements on many zircons, then assessing the quality of the data.
That would take the zircons on a straight line back to zero on the concordia diagram.Other minerals sometimes used for uranium-lead dating include monazite, titanite and two other zirconium minerals, baddeleyite and zirconolite.However, zircon is so overwhelming a favorite that geologists often just refer to "zircon dating." But even the best geologic methods are imperfect.In a 704-million-year-old rock, 235U is at its half-life and there will be an equal number of 235U and 207Pb atoms (the Pb/U ratio is 1).In a rock twice as old there will be one 235U atom left for every three 207Pb atoms (Pb/U = 3), and so forth.