rubidium-strontium dating

rubidium-strontium dating
/rooh bid"ee euhm stron"shee euhm, -sheuhm, -tee euhm/, Geol.
a radiometric dating method whereby the ratio of rubidium isotope to strontium in a mineral is used to calculate the age of the mineral, based on the rate of radioactive decay of rubidium to strontium.
[1965-70]

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Method of estimating the age of rocks, minerals, and meteorites from measurements of the amount of the stable isotope strontium-87 formed by the decay of the unstable isotope rubidium-87 that was present in the rock at the time of its formation.

The method is applicable to very old rocks because the transformation is extremely slow: the half-life, or time required for half the initial quantity of rubidium-87 to disappear, is approximately 48.8 billion years. See also dating.

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      method of estimating the age of rocks, minerals, and meteorites from measurements of the amount of the stable isotope strontium-87 formed by the decay of the unstable isotope rubidium-87 (rubidium) that was present in the rock at the time of its formation. Rubidium-87 comprises 27.85 percent of the total atomic abundance of rubidium, and of the four isotopes of strontium, only strontium-87 is formed by its decay. The method is applicable to very old rocks because the transformation is extremely slow: the half-life, or time required for half the initial quantity of rubidium-87 to disappear, is approximately 50 billion years.

      Most minerals that contain rubidium also have some strontium incorporated when the mineral was formed, so a correction must be made for this initial amount of strontium to obtain the radiogenic increment (i.e., the increase due to decay of rubidium-87).

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Universalium. 2010.

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