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thorium-lead dating

A Dictionary of Earth Sciences | 1999 | | Copyright

thorium-lead dating A radiometric dating method based on the radioactive decay of ²³²Th, to yield ²⁰⁸Pb + 6He⁴, with a half-life (see DECAY CONSTANT) of 13 900 million years. The minerals used include sphene, zircon, monazite, apatite, and other rare U/Th minerals. The method is not totally reliable and is usually employed in conjunction with other methods. In most cases the results are discordant as a result of lead loss. The ratio of ²⁰⁸Pb: ²³²Th compared with ²⁰⁷Pb: ²³⁵U ratio is particularly useful. The Th-Pb system can also be interpreted by means of isochron diagrams similar to those used in the rubidium-strontium method.

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AILSA ALLABY and MICHAEL ALLABY. "thorium-lead dating." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "thorium-lead dating." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O13-thoriumleaddating.html

AILSA ALLABY and MICHAEL ALLABY. "thorium-lead dating." A Dictionary of Earth Sciences. 1999. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-thoriumleaddating.html

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thorium–lead dating

A Dictionary of Ecology | 2004 | | Copyright

thorium–lead dating A radiometric dating method based on the radioactive decay of ²³²Th, to yield ²⁰⁸Pb + 6He⁴, with a half-life of 13 900 million years. The method is not totally reliable, in most cases because of lead loss, and it is usually employed in conjunction with other methods.

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MICHAEL ALLABY. "thorium–lead dating." A Dictionary of Ecology. 2004. Encyclopedia.com. 1 Jun. 2012 <http://www.encyclopedia.com>.

MICHAEL ALLABY. "thorium–lead dating." A Dictionary of Ecology. 2004. Encyclopedia.com. (June 1, 2012). http://www.encyclopedia.com/doc/1O14-thoriumleaddating.html

MICHAEL ALLABY. "thorium–lead dating." A Dictionary of Ecology. 2004. Retrieved June 01, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-thoriumleaddating.html

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