The radiocarbon method is applied in many different scientific fields, including archeology, geology, oceanography, hydrology, atmospheric science, and paleoclimatology.For his leadership, Libby received the Nobel Prize in Chemistry in 1960. our C14 dating calculator Dating Rocks with the Rb-Sr "Isochron" Method As you know, there are numerous radioactive isotopes that can be used for numeric dating.
Rubidium occurs in nature as two isotopes: radioactive Rb-87 and stable Rb-85.
Rb-87 decays with a half-life of 48.8 billion years to Sr-87.
It's this compound of Rb-Sr salts that can be attached to a special filament and placed into the mass spectrometer for analysis. Analyze the isotopic compositions of the whole rock and mineral separates on a mass spectrometer.
A Mass Spectrometer is used to Measure Isotopic Ratios A Mass Spectrometer is a very powerful and sophisticated instrument. Below is a simplified diagram of the electro-mechanical mass spectrometer system and a picture of a modern instrument.
All of the dating methods rely on the fundamental principles of radioactive decay, but the specific materials that can be dated and the exact procedures for calculating a date are very different from one method to the next.
The rest of this activity is about using the Rb-Sr method.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.It illustrates how the amount of a radioactive parent isotope decreases with time. For example when 42% of the parent still remains, 1.23 Half-Lives of time has passed.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.Which minerals and rocks can be dated with the Rb-Sr method?Understanding the isochron diagram is the key to determining the age of a rock using the Rb-Sr method.