Cindy Humphrey, 23 years old
Uranium-Lead dating is a radiometric dating method that uses the decay chain of uranium and lead to find the age of a rock. As uranium decays radioactively, it becomes different chemical elements until it stops at lead. The reason for uranium 238 lead 206 dating at lead is because lead is not radioactive and will not change into a different element. It may sound straight-forward, but there are many variables that have to be considered. The three main parameters that have to be set are the original amount of uranium and lead in the sample, the rate at which uranium and lead enter and leave the sample, and how much the rate of decay changes.
Of all the isotopic dating methods in use today, the uranium-lead method is the oldest and, when done carefully, the most reliable. Unlike any other method, uranium-lead has a natural cross-check built into it that shows when nature has tampered with the evidence. Uranium comes in two common isotopes with atomic weights of and we'll call them U and U. Both are unstable and radioactive, shedding nuclear particles in a cascade that doesn't stop until they become lead Pb. The two cascades are different—U becomes Pb and U becomes Pb. What makes this fact useful is that they occur at different rates, as expressed in their half-lives the time it takes for half the atoms to decay. The U—Pb cascade uranium 238 lead 206 dating a half-life of uranium 238 lead 206 dating years and the U—Pb cascade is considerably slower, with a half-life of 4. So when a mineral grain forms specifically, when it first cools below its trapping temperatureit effectively sets the uranium-lead "clock" to zero.
Unlike uraniumit is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable uranium 238 lead 206 dating fast neutrons, and is fertilemeaning it can be transmuted to fissile plutonium Doppler broadening of U's neutron absorption resonancesincreasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control. Around Depleted uranium has an even higher concentration of the U isotope, and even low-enriched uranium LEUwhile having a higher proportion of the uranium isotope in comparison to depleted uraniumis still mostly U.
Uranium 238 lead 206 dating
More about uranium 238 lead 206 dating:
Uranium—lead datingabbreviated U—Pb datingis one of the oldest  and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised  from about 1 uranium 238 lead 206 dating years to over 4. The dating method is usually performed on the mineral zircon. The mineral incorporates uranium and thorium atoms into its crystal structurebut strongly rejects lead. Therefore, one can assume that the entire lead content of the zircon is radiogenici. Thus the current ratio of lead to uranium in the mineral can be used to determine its age [ citation needed ]. The method relies on two separate decay chainsthe uranium series from U to Pb, with a half-life of 4. The above uranium to lead decay routes occur via a series of alpha and beta decays, in which U with daughter nuclides undergo total eight alpha and six beta decays whereas U with daughters only experience seven alpha and four beta decays. The existence of two 'parallel' uranium—lead decay routes U to Pb and U to Pb leads to multiple dating techniques within the overall U—Pb system.
Both isotopes are the starting points for complex decay series that eventually produce stable isotopes of lead. Uranium-lead dating was applied initially to uranium minerals, e. The amount of radiogenic lead from all these methods must be distinguished from naturally occurring lead, and this is calculated by using the ratio with Pb, which is a stable isotope of the element then, after correcting for original lead, if the mineral has remained in a closed system, the U: If this is the uranium 238 lead 206 dating, they are concordant and the age determined is most probably the actual age of the specimen. If the ages determined using these two methods do not agree, then they do not fall on this curve and are therefore discordant. This commonly occurs if the system has been heated or otherwise disturbed, causing a loss of some of the lead daughter atoms. Because Pb and Pb are chemically identical, they are usually lost in the same proportions. The plot of the ratios will then produce a straight line below the Concordia curve.
uranium 238 lead 206 dating