Pictures on radioactive dating
For example, carbon dating is used to determine the age of organic materials.Once something dies, it ceases taking in new carbon-14, and the existing carbon-14 within the organism decays into nitrogen at a fixed rate.These minerals are abundant in granite (an igneous rock) and gneiss (a metamorphic rock). Weathering alters the chemistry of rocks including their isotopic compositions.Therefore, a highly weathered rock may yield unreliable age information. Crush the rock and separate the Rb-bearing minerals.Which minerals and rocks can be dated with the Rb-Sr method?The minerals must contain Rb, which is a rather rare element.
This half-life is so long that the Rb-Sr method is normally only used to date rocks that are older than about 100 million years.
("87" is the atomic mass number = protons neutrons.
Numerical ages have been added to the Geologic Time Scale since the advent of radioactive age-dating techniques. In theory, the age of any of these minerals can be determined by: 1) counting the number of daughter isotopes in the mineral, and 2) using the known decay rate to calculate the length of time required to produce that number of daughters.
Numerical dating, the focus of this exercise, takes advantage of the "clocks in rocks" - radioactive isotopes ("parents") that spontaneously decay to form new isotopes ("daughters") while releasing energy.
For example, decay of the parent isotope Rb-87 (Rubidium) produces a stable daughter isotope, Sr-87 (Strontium), while releasing a beta particle (an electron from the nucleus).