Absolute Age Dating

  I. You have analyzed a rock sample using a mass spectrometer and have determined that the sum of the isotopes (i.e., parent + daughter) is always equal to 128 ppm. Using this information, the assumption of zero daughter at time=0, and your understanding of how radiogenic isotopes decay, complete the MS Excel spreadsheet provided. Start with the sum of the isotopes (in the highlighted cell) and use equations for the remaining cells. 2. Plot the concentration of Kazmarium and the concentration of Kehewium (ppm) as a function of the number of half-lives. This will be Figure 1. 3. Comment on the relationship between the variables plotted in Figure 1. 4. On another graph (Figure 2) cross-plot the "# of half-lives" (on the Y-axis) as a function of the parent ratio (on the X-axis). Parent Concentration Parent Ratio = (Parent Concentration + Daughter Concentration) 5. Add a logarithmic trend-line to the data in Figure 2. What is the equation for the trend-line? What does y represent? What does x represent?