Methods of radiometric dating Live one on one chat with granny free

18.3.2 Method This is based on the beta decay of rubidium-87 to strontium-87, with a half-life of 50 billion years.This scheme is used to date old igneous and metamorphic rocks, and has also been used to date lunar samples.The mass spectrometer operates by generating a beam of ionized atoms from the sample under test.

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On impact in the cups, the ions set up a very weak current that can be measured to determine the rate of impacts and the relative concentrations of different atoms in the beams.

18.3.1 Uranium-Lead Dating Method A Concordia diagram as used in uranium-lead dating, with data from the Pfunze Belt, Zimbabwe.

18.3.6 Radiocarbon Dating Method Radiocarbon dating, or carbon dating, is a radiometric dating method that uses the naturally occurring radioisotope carbon-14 (14C) to determine the age of carbonaceous materials up to about 60,000 years.

Carbon-14 is a radioactive isotope of carbon, with a half-life of 5,730 years, which is very short compared with those above.

18.3.5 Uranium-Thorium Dating Method A relatively short-range dating technique is based on the decay of uranium-238 into thorium-230, a substance with a half-life of about 80,000 years.

It is accompanied by a sister process, in which uranium-235 decays into protactinium-231, which has a half-life of 34,300 years.The parent isotopes have been decaying since they were formed in the stars, and so any parent isotope with a short half-life should be extinct by now. It is continuously created through collisions of neutrons generated by cosmic rays with nitrogen in the upper atmosphere.The carbon-14 ends up as a trace component in atmospheric carbon dioxide (CO2). Plants acquire it through photosynthesis, and animals acquire it from consumption of plants and other animals.The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere.Atmospheric nuclear weapon tests almost doubled the concentration of 14C in the Northern Hemisphere.An error margin of 2–5 % has been achieved on younger Mesozoic rocks.

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