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Thorium-230 is itself radioactive with a half-life of 75,000 years, [4] so instead of accumulating indefinitely (as for instance is the case for the uranium–lead system), thorium-230 instead approaches secular equilibrium with its radioactive parent uranium-234. At secular equilibrium, the number of thorium-230 decays per year within a sample ...
Uranium–lead dating, abbreviated U–Pb dating, is one of the oldest [1] and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4.5 billion years ago with routine precisions in the 0.1–1 percent range. [2] [3] The method is usually applied to zircon.
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 ...
Lead–lead dating is a method for dating geological samples, normally based on 'whole-rock' samples of material such as granite.For most dating requirements it has been superseded by uranium–lead dating (U–Pb dating), but in certain specialized situations (such as dating meteorites and the age of the Earth) it is more important than U–Pb dating.
Uranium–lead dating; Uranium–thorium dating; Uranium–uranium dating This page was last edited on 16 February 2022, at 02:25 (UTC) ...
Samarium–neodymium dating; Tephrochronology; Uranium–lead dating; Uranium–thorium dating; Uranium–uranium dating, useful in dating samples between about 10,000 and 2 million years Before Present (BP), or up to about eight times the half-life of 234U. Wiggle matching
Monazite geochronology is another example of U–Pb dating, employed for dating metamorphism in particular. Uranium–lead dating is applied to samples older than about 1 million years. Uranium–thorium dating. This technique is used to date speleothems, corals, carbonates, and fossil bones. Its range is from a few years to about 700,000 years.
(U-Th)/He dating is used to measure the age of a sample by measuring the amount of radiogenic helium (4 He) present as a result of the alpha decay from uranium and thorium. This helium product is kept in the mineral until the closure temperature is reached, and therefore can be determinant of the thermal evolution of the mineral.