| Uranium-lead Dating |
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| CATEGORIES ABOUT URANIUM-LEAD DATING | |
| radiometric dating | |
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Uranium - Lead dating is usually performed on the mineral Zircon (ZrSiO4), though it can be used on other materials. Zircon incorporates uranium Atom s into its crystalline structure as substitutes for Zirconium , but strongly rejects lead. It has a very high blocking temperature, is resistant to mechanical weathering and is very chemically inert. Zircon also forms multiple crystal layers during metamorphic events, which each may record an isotopic age of the event. These can be dated by a SHRIMP Ion microprobe. One of its great advantages is that any sample provides two clocks, one based on uranium-235's decay to lead-207 with a Half-life of about 700 million years, and one based on uranium-238's decay to lead-206 with a half-life of about 4.5 billion years, providing a built-in crosscheck that allows accurate determination of the age of the sample even if some of the lead has been lost. SEE ALSO |
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