helium dating

Method of dating that depends on the production of helium during the decay of radioactive isotopes of uranium and thorium.

Because of this decay, the helium content of any mineral or rock capable of retaining helium will increase during the lifetime of that mineral or rock, and the ratio of helium to its radioactive progenitors then becomes a measure of geologic time. Fossils may also be dated by helium dating. The relatively large amount of helium produced in rocks may make it possible to extend helium dating to rocks and minerals as young as a few tens of thousands of years old.

* * *

      method of age determination that depends on the production of helium during the decay of the radioactive isotopes uranium-235, uranium-238, and thorium-232. Because of this decay, the helium content of any mineral or rock capable of retaining helium will increase during the lifetime of that mineral or rock, and the ratio of helium to its radioactive progenitors then becomes a measure of geologic time. If the parent isotopes are measured, the helium dating method is referred to as uranium–thorium–helium dating; if only the alpha-particle emission and helium content are measured, the method is called the alpha-helium radioactive clock. Alpha particles are the nuclei of helium atoms emitted from the nucleus of the radioactive progenitor.

      Before the use of mass spectrometry in isotopic geochronology, helium dating provided most of the dates used in the early geologic time scales. Helium ages, however, tend to be too low because the gas escapes from the rock. A thermal event that will leave most radioactive clocks relatively unaffected may have a drastic effect on the helium radioactive clock. In the future, helium dating may be found very useful for dating rocks of the late Cenozoic and Pleistocene, because rocks and minerals of this age have not been subject to the complex history of older rocks and minerals; thus, all the helium is more likely to have been retained. Fossils, as well as minerals and rocks, may be dated by helium dating. The relatively large amount of helium produced in rocks may make it possible to extend helium dating to rocks and minerals as young as a few tens of thousands of years old.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Helium dating — is a method of determining the age of a substance using the decay of radioactive isotopes …   Wikipedia

  • helium dating — noun a method of determining the age of rock that depends on the production of helium during the decay of various radioactive isotopes of uranium and thorium. Syn: He dating …   Wiktionary

  • Helium (disambiguation) — Helium, in science and astronomy, may refer to:*Helium, chemical element **Helium 3, an isotope of helium **Helium 4, an isotope of helium *Helium dating, a method of determining the age of rocks *Helium fusion, a type of nuclear fusion in stars… …   Wikipedia

  • dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …   Universalium

  • Helium — otherusesHelium (He) is a colorless, odorless, tasteless, non toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the… …   Wikipedia

  • helium — /hee lee euhm/, n. an inert, gaseous element present in the sun s atmosphere and in natural gas, and also occurring as a radioactive decomposition product, used as a substitute for flammable gases in dirigible balloons. Symbol: He; at. wt.:… …   Universalium

  • He dating — noun Helium dating …   Wiktionary

  • Radiometric dating — (often called radioactive dating) is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.[1]… …   Wikipedia

  • Period 1 element — A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the… …   Wikipedia

  • Portal:Chemistry — Wikipedia portals: Culture Geography Health History Mathematics Natural sciences People Philosophy Religion Society Technology …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.