Age of solar system radioactive dating
The basic theory of radiometric dating is briefly reviewed.
Since the lead in meteorites can no longer be ascribed to uranium/thorium decay, it may also be taken to represent primordial lead.For teaching and sharing purposes, readers are advised to supplement these historic articles with more up-to-date ones suggested in the Related Articles and Further Reading below.Before 1955, ages for the Earth based on uranium/thorium/lead ratios were generally about a billion years younger than the currently popular 4.5 billion years. old Earth is reviewed and deficiencies of the uranium/lead method are discussed.Because it is not generally appreciated that the assumptions on which the radiometric estimates are based are a virtually impossible sequence of events, let us refresh our minds on the fundamentals of the method by turning to the hourglass analogy (Fig. This system of measuring time works well providing that: Since radioactive decay constants are believed to be unalterable, the requirement of an absolutely reproducible rate is hopefully met.Therefore, all one has to do in general terms is to find a radioactive mineral which has been a closed system since the time of mineralization, and for which the amount of the daughter product at the beginning is known, the so-called primordial amount, and the absolute age may be calculated from the present amount of parent and daughter isotopes in the mineral.The Solar System was formed around 4.6 billion years ago, out of the collapse of a dense cloud composed of dusts and gases.
Meteorites, which are the very components of our planets (through the process of accretion), are the remnants of the Solar System’s origins.
It has assumed something of the status of a universal constant to which all other data must be fitted, thus it has become common practice to assume that data which does not fit this result is either wrong or unintelligible. Lead-204, a minor isotope of common lead, has no radioactive parent and is believed to be primordial lead.
Lead-206 and lead-207 are also believed to be present in primordial lead since there is insufficient uranium to account for all the lead.
The animation shows progressive growth over 4550 million years (Myr) of the lead isotope ratios for two stony meteorites (Nuevo Laredo and Forest City) from initial lead isotope ratios matching those of the Canyon Diablo iron meteorite.
magazine has been continuously published since 1978, we are publishing some of the articles from the archives for historical interest, such as this.
This age has been determined with the radioactive dating technique.